2014-15 Human Anatomy & Physiology Final Exam Review 100 questions. Multiple choice and labeling of structures.

Here is a VERY good review of the chapters, don’t forget to use our class website

resources as well. Use your book for clarification of any material. I know it looks like a lot, but you know most of it already. My suggestion is that you read through this and

make stars next to the parts that you feel you need to go back and study.

**Labeling… Be sure you know the structures of the significant parts of each system.**

Chapter 10-Blood (pages 339-359) § Blood

o The only fluid tissue in the human body o Classified as a connective tissue o Components of blood

§ Living cells • Formed elements

§ Non-living matrix • Plasma

o If blood is centrifuged § Erythrocytes sink to the bottom (45% of blood, a percentage known as the

hematocrit) § Buffy coat contains leukocytes and platelets (less than 1% of blood)

• Buffy coat is a thin, whitish layer between the erythrocytes and plasma § Plasma rises to the top (55% of blood)

o Physical Characteristics of Blood § Color range

• Oxygen-rich blood is scarlet red • Oxygen-poor blood is dull red

§ pH must remain between 7.35–7.45 § Blood temperature is slightly higher than body temperature at 100.4°F § In a healthy man, blood volume is about 5–6 liters or about 6 quarts § Blood makes up 8% of body weight

o Blood Plasma § Composed of approximately 90% water § Includes many dissolved substances

• Nutrients • Salts (electrolytes) • Respiratory gases • Hormones • Plasma proteins • Waste products • Plasma proteins

o Most abundant solutes in plasma o Most plasma proteins are made by liver o Various plasma proteins include

§ Albumin—regulates osmotic pressure § Clotting proteins—help to stem blood loss when a blood

vessel is injured § Antibodies—help protect the body from pathogens

o Acidosis § Blood becomes too acidic

o Alkalosis § Blood becomes too basic

o Formed Elements § Erythrocytes (red blood cells or RBCs)

• Main function is to carry oxygen • Anatomy of circulating erythrocytes

o Biconcave disks o Essentially bags of hemoglobin o Anucleate (no nucleus) o Contain very few organelles o 5 million RBCs per cubic millimeter of blood

• Hemoglobin o Iron-containing protein o Binds strongly, but reversibly, to oxygen o Each hemoglobin molecule has four oxygen binding sites o Each erythrocyte has 250 million hemoglobin molecules o Normal blood contains 12–18 g of hemoglobin per 100 mL blood

• Homeostatic imbalance of RBCs o Anemia is a decrease in the oxygen-carrying ability of the blood o Sickle cell anemia (SCA) results from abnormally shaped

hemoglobin o Polycythemia is an excessive or abnormal increase in the

number of erythrocytes § Leukocytes (white blood cells or WBCs)

• Crucial in the body’s defense against disease • These are complete cells, with a nucleus and organelles • Able to move into and out of blood vessels (diapedesis) • Can move by ameboid motion • Can respond to chemicals released by damaged tissues • 4,000 to 11,000 WBC per cubic millimeter of blood • Abnormal numbers of leukocytes

o Leukocytosis § WBC count above 11,000 leukocytes/mm3 § Generally indicates an infection

o Leukopenia § Abnormally low leukocyte level § Commonly caused by certain drugs such as

corticosteroids and anticancer agents o Leukemia

§ Bone marrow becomes cancerous, turns out excess WBC

• Types of leukocytes o Granulocytes

§ Granules in their cytoplasm can be stained § Possess lobed nuclei § Include neutrophils, eosinophils, and basophils

o Agranulocytes § Lack visible cytoplasmic granules § Nuclei are spherical, oval, or kidney-shaped § Include lymphocytes and monocytes

• List of the WBCs from most to least abundant o Neutrophils o Lymphocytes

o Monocytes o Eosinophils o Basophils

• Easy way to remember this list o Never o Let o Monkeys o Eat o Bananas

• Types of granulocytes o Neutrophils

§ Multilobed nucleus with fine granules § Act as phagocytes at active sites of infection

o Eosinophils § Large brick-red cytoplasmic granules § Found in response to allergies and parasitic worms

o Basophils § Have histamine-containing granules § Initiate inflammation

• Types of agranulocytes o Lymphocytes

§ Nucleus fills most of the cell § Play an important role in the immune response

o Monocytes § Largest of the white blood cells § Function as macrophages § Important in fighting chronic infection

§ Platelets • Derived from ruptured multinucleate cells (megakaryocytes) • Needed for the clotting process • Normal platelet count = 300,000/mm3

o Hematopoiesis § Blood cell formation § Occurs in red bone marrow § All blood cells are derived from a common stem cell (hemocytoblast)

• Hemocytoblast differentiation o Lymphoid stem cell produces lymphocytes o Myeloid stem cell produces all other formed elements

§ Formation of Erythrocytes • Unable to divide, grow, or synthesize proteins • Wear out in 100 to 120 days • When worn out, RBCs are eliminated by phagocytes in the spleen or

liver • Lost cells are replaced by division of hemocytoblasts in the red bone

marrow § Control of Erythrocyte Production

• Rate is controlled by a hormone (erythropoietin) • Kidneys produce most erythropoietin as a response to reduced oxygen

levels in the blood • Homeostasis is maintained by negative feedback from blood oxygen

levels § Formation of White Blood Cells and Platelets

• Controlled by hormones

o Colony stimulating factors (CSFs) and interleukins prompt bone marrow to generate leukocytes

o Thrombopoietin stimulates production of platelets o Hemostasis

§ Stoppage of bleeding resulting from a break in a blood vessel § Hemostasis involves three phases

• Vascular spasms o Vasoconstriction causes blood vessel to spasm o Spasms narrow the blood vessel, decreasing blood loss

• Platelet plug formation o Collagen fibers are exposed by a break in a blood vessel o Platelets become “sticky” and cling to fibers o Anchored platelets release chemicals to attract more platelets o Platelets pile up to form a platelet plug

• Coagulation o Injured tissues release tissue factor (TF) o PF3 (a phospholipid) interacts with TF, blood protein clotting

factors, and calcium ions to trigger a clotting cascade o Prothrombin activator converts prothrombin to thrombin (an

enzyme) o Thrombin joins fibrinogen proteins into hair-like molecules of

insoluble fibrin o Fibrin forms a meshwork (the basis for a clot)

• Blood usually clots within 3 to 6 minutes • The clot remains as endothelium regenerates • The clot is broken down after tissue repair • Undesirable Clotting

o Thrombus § A clot in an unbroken blood vessel § Can be deadly in areas like the heart

o Embolus § A thrombus that breaks away and floats freely in the

bloodstream § Can later clog vessels in critical areas such as the brain

§ Bleeding Disorders • Thrombocytopenia

o Platelet deficiency o Even normal movements can cause bleeding from small blood

vessels that require platelets for clotting • Hemophilia

o Hereditary bleeding disorder o Normal clotting factors are missing

§ Blood Groups and Transfusions o Large losses of blood have serious consequences

§ Loss of 15–30% causes weakness § Loss of over 30% causes shock, which can be fatal

o Transfusions are the only way to replace blood quickly o Transfused blood must be of the same blood group o Human Blood Groups

§ Blood contains genetically determined proteins § Antigens (a substance the body recognizes as foreign) may be attacked by the

immune system § Antibodies are the “recognizers”

§ Blood is “typed” by using antibodies that will cause blood with certain proteins to clump (agglutination)

§ There are over 30 common red blood cell antigens § The most vigorous transfusion reactions are caused by ABO and Rh blood

group antigens § ABO Blood Groups

• Based on the presence or absence of two antigens o Type A o Type B

• The lack of these antigens is called type O • The presence of both antigens A and B is called type AB • The presence of antigen A is called type A • The presence of antigen B is called type B • The lack of both antigens A and B is called type O • Blood type AB can receive A, B, AB, and O blood

o Universal recipient • Blood type B can receive B and O blood • Blood type A can receive A and O blood • Blood type O can receive O blood

o Universal donor § Rh Blood Groups

• Named because of the presence or absence of one of eight Rh antigens (agglutinogen D) that was originally defined in Rhesus monkeys

• Most Americans are Rh+ (Rh positive) • Problems can occur in mixing Rh+ blood into a body with Rh– (Rh

negative) blood Rh Dangers During Pregnancy • Danger occurs only when the mother is Rh– and the father is Rh+, and

the child inherits the Rh+ factor • RhoGAM shot can prevent buildup of anti-Rh+ antibodies in mother’s

blood • Rh Dangers During Pregnancy

o The mismatch of an Rh– mother carrying an Rh+ baby can cause problems for the unborn child

o The first pregnancy usually proceeds without problems o The immune system is sensitized after the first pregnancy o In a second pregnancy, the mother’s immune system produces

antibodies to attack the Rh+ blood (hemolytic disease of the newborn)

§ Blood Typing • Blood samples are mixed with anti-A and anti-B serum • Coagulation or no coagulation leads to determining blood type • Typing for ABO and Rh factors is done in the same manner • Cross matching—testing for agglutination of donor RBCs by the

recipient’s serum, and vice versa Chapter 11-The Cardiovascular System (pages 360-401)

§ A closed system of the heart and blood vessels o The heart pumps blood o Blood vessels allow blood to circulate to all parts of the body

§ The function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products

§ The Heart o Location

§ Thorax between the lungs in the inferior mediastinum o Orientation

§ Pointed apex directed toward left hip § Base points toward right shoulder

o About the size of your fist § The Heart: Coverings

o Pericardium—a double-walled sac o Fibrous pericardium is loose and superficial o Serous membrane is deep to the fibrous pericardium and composed of two layers

§ Visceral pericardium • Next to heart; also known as the epicardium

§ Parietal pericardium • Outside layer that lines the inner surface of the fibrous pericardium

§ Serous fluid fills the space between the layers of pericardium § The Heart: Heart Wall

o Three layers § Epicardium

• Outside layer • This layer is the visceral pericardium • Connective tissue layer

§ Myocardium • Middle layer • Mostly cardiac muscle

§ Endocardium • Inner layer • Endothelium

§ The Heart: Chambers o Right and left side act as separate pumps o Four chambers

§ Atria • Receiving chambers

§ Ventricles • Discharging chambers

o Differences in Right and Left Ventricles § The Heart: Septa

o Interventricular septum § Separates the two ventricles

o Interatrial septum § Separates the two atria

§ The Heart: Valves o Allow blood to flow in only one direction to prevent backflow o Four valves

§ Atrioventricular (AV) valves—between atria and ventricles • Bicuspid (mitral) valve (left side of heart) • Tricuspid valve (right side of heart)

§ Semilunar valves—between ventricle and artery • Pulmonary semilunar valve • Aortic semilunar valve

o AV valves § Anchored in place by chordae tendineae (“heart strings”) § Open during heart relaxation and closed during ventricular contraction

o Semilunar valves § Closed during heart relaxation but open during ventricular contraction

o Notice these valves operate opposite of one another to force a one-way path of blood through the heart

§ Systemic and Pulmonary Circulations o Systemic circulation

§ Blood flows from the left side of the heart through the body tissues and back to the right side of the heart

o Pulmonary circulation § Blood flows from the right side of the heart to the lungs and back to the left

side of the heart § The Heart: Associated Great Vessels

o Arteries § Aorta

• Leaves left ventricle § Pulmonary arteries

• Leave right ventricle o Veins

§ Superior and inferior venae cavae • Enter right atrium

§ Pulmonary veins (four) • Enter left atrium

§ Blood Flow Through the Heart o Superior and inferior venae cavae dump blood into the right atrium o From right atrium, through the tricuspid valve, blood travels to the right ventricle o From the right ventricle, blood leaves the heart as it passes through the pulmonary

semilunar valve into the pulmonary trunk o Pulmonary trunk splits into right and left pulmonary arteries that carry blood to the

lungs o Oxygen is picked up and carbon dioxide is dropped off by blood in the lungs o Oxygen-rich blood returns to the heart through the four pulmonary veins o Blood enters the left atrium and travels through the bicuspid valve into the left

ventricle o From the left ventricle, blood leaves the heart via the aortic semilunar valve and aorta

§ Coronary Circulation o Blood in the heart chambers does not nourish the myocardium o The heart has its own nourishing circulatory system consisting of

§ Coronary arteries—branch from the aorta to supply the heart muscle with oxygenated blood

§ Cardiac veins—drain the myocardium of blood § Coronary sinus—a large vein on the posterior of the heart, receives blood from

cardiac veins • Blood empties into the right atrium via the coronary sinus

§ The Heart: Conduction System o Intrinsic conduction system (nodal system)

§ Heart muscle cells contract, without nerve impulses, in a regular, continuous way

§ Special tissue sets the pace • Sinoatrial node = SA node (“pacemaker”), is in the right atrium • Atrioventricular node = AV node, is at the junction of the atria and

ventricles • Atrioventricular bundle = AV bundle (bundle of His), is in the

interventricular septum

• Bundle branches are in the interventricular septum • Purkinje fibers spread within the ventricle wall muscles

o Heart Contractions § Contraction is initiated by the sinoatrial node (SA node) § Sequential stimulation occurs at other autorhythmic cells § Force cardiac muscle depolarization in one direction—from atria to ventricles § Once SA node starts the heartbeat

• Impulse spreads to the AV node o Then the atria contract

• At the AV node, the impulse passes through the AV bundle, bundle branches, and Purkinje fibers

• Blood is ejected from the ventricles to the aorta and pulmonary trunk as the ventricles contract

§ Tachycardia—rapid heart rate over 100 beats per minute § Bradycardia—slow heart rate less than 60 beats per minutes

§ The Heart: Cardiac Cycle o Atria contract simultaneously o Atria relax, then ventricles contract o Asystole = contraction o Diastole = relaxation o Cardiac cycle—events of one complete heart beat

§ Mid-to-late diastole—blood flows from atria into ventricles § Ventricular systole—blood pressure builds before ventricle contracts, pushing

out blood § Early diastole—atria finish refilling, ventricular pressure is low

§ The Heart: Cardiac Output o Cardiac output (CO)

§ Amount of blood pumped by each side (ventricle) of the heart in one minute o Stroke volume (SV)

§ Volume of blood pumped by each ventricle in one contraction (each heartbeat) § Usually remains relatively constant § About 70 mL of blood is pumped out of the left ventricle with each heartbeat

o Heart rate (HR) § Typically 75 beats per minute

o CO = HR × SV § CO = HR (75 beats/min) × SV (70 mL/beat) § CO = 5250 mL/min

o Starling’s law of the heart—the more the cardiac muscle is stretched, the stronger the contraction

o Changing heart rate is the most common way to change cardiac output § The Heart: Regulation of Heart Rate

o Increased heart rate § Sympathetic nervous system

• Crisis • Low blood pressure

§ Hormones • Epinephrine • Thyroxine

§ Exercise § Decreased blood volume

o Decreased heart rate § Parasympathetic nervous system § High blood pressure or blood volume

§ Decreased venous return § Blood Vessels: The Vascular System

o Transport blood to the tissues and back o Carry blood away from the heart

§ Arteries § Arterioles

o Exchanges between tissues and blood § Capillary beds

o Return blood toward the heart § Venules § Veins

§ Blood Vessels: Microscopic Anatomy o Three layers (tunics)

§ Tunic intima • Endothelium

§ Tunic media • Smooth muscle • Controlled by sympathetic nervous system

§ Tunic externa • Mostly fibrous connective tissue

§ Differences Between Blood Vessels o Walls of arteries are the thickest o Lumens of veins are larger o Larger veins have valves to prevent backflow o Skeletal muscle “milks” blood in veins toward the heart o Walls of capillaries are only one cell layer thick to allow for exchanges between blood

and tissue § Movement of Blood Through Vessels

o Most arterial blood is pumped by the heart o Veins use the milking action of muscles to help move blood

§ Capillary Beds o Capillary beds consist of two types of vessels

§ Vascular shunt—vessel directly connecting an arteriole to a venule § True capillaries—exchange vessels

• Oxygen and nutrients cross to cells • Carbon dioxide and metabolic waste products cross into blood

§ Major Arteries of Systemic Circulation o Aorta

§ Largest artery in the body § Leaves from the left ventricle of the heart § Regions

• Ascending aorta—leaves the left ventricle • Aortic arch—arches to the left • Thoracic aorta—travels downward through the thorax • Abdominal aorta—passes through the diaphragm into the

abdominopelvic cavity o Arterial branches of the ascending aorta

§ Right and left coronary arteries serve the heart o Arterial branches of the aortia arch (BCS)

§ Brachiocephalic trunk splits into the • Right common carotid artery • Right subclavian artery

§ Left common carotid artery splits into the

• Left internal and external carotid arteries § Left subclavian artery branches into the

• Vertebral artery • In the axilla, the subclavian artery becomes the axillary artery à

brachial artery à radial and ulnar arteries o Arterial branches of the thoracic aorta

§ Intercostal arteries supply the muscles of the thorax wall § Other branches of the thoracic aorta supply the

• Lungs (bronchial arteries) • Esophagus (esophageal arteries) • Diaphragm (phrenic arteries)

o Arterial branches of the abdominal aorta § Celiac trunk is the first branch of the abdominal aorta. Three branches are

• Left gastric artery (stomach) • Splenic artery (spleen) • Common hepatic artery (liver)

§ Superior mesenteric artery supplies most of the small intestine and first half of the large intestine

§ Left and right renal arteries (kidney) § Left and right gonadal arteries

• Ovarian arteries in females serve the ovaries • Testicular arteries in males serve the testes

§ Lumbar arteries serve muscles of the abdomen and trunk § Inferior mesenteric artery serves the second half of the large intestine § Left and right common iliac arteries are the final branches of the aorta

• Internal iliac arteries serve the pelvic organs • External iliac arteries enter the thigh à femoral artery à popliteal

artery à anterior and posterior tibial arteries o Superior and inferior vena cava enter the right atrium of the heart

§ Superior vena cava drains the head and arms § Inferior vena cava drains the lower body

o Veins draining into the superior vena cava § Radial and ulnar veins à brachial vein à axillary vein

• These veins drain the arms § Cephalic vein drains the lateral aspect of the arm and empties into the axillary

vein § Basilic vein drains the medial aspect of the arm and empties into the brachial

vein § Basilic and cephalic veins are jointed at the median cubital vein (elbow area) § Subclavian vein receives

• Venous blood from the arm via the axillary vein • Venous blood from skin and muscles via external jugular vein

§ Vertebral vein drains the posterior part of the head § Internal jugular vein drains the dural sinuses of the brain § Left and right brachiocephalic veins receive venous blood from the

• Subclavian veins • Vertebral veins • Internal jugular veins

§ Brachiocephalic veins join to form the superior vena cava à right atrium of heart

§ Azygous vein drains the thorax o Veins draining into the inferior vena cava

§ Anterior and posterior tibial veins and fibial veins drain the legs § Posterior tibial vein à popliteal vein à femoral vein à external iliac vein § Great saphenous veins (longest veins of the body) receive superficial drainage

of the legs § Each common iliac vein (left and right) is formed by the union of the internal

and external iliac vein on its own side § Right gonadal vein drains the right ovary in females and right testicle in males § Left gonadal vein empties into the left renal vein § Left and right renal veins drain the kidneys § Hepatic portal vein drains the digestive organs and travels through the liver

before it enters systemic circulation § Left and right hepatic veins drain the liver

o Arterial Supply of the Brain § Internal carotid arteries divide into

• Anterior and middle cerebral arteries • These arteries supply most of the cerebrum

§ Vertebral arteries join once within the skull to form the basilar artery § Basilar artery serves the brain stem and cerebellum § Posterior cerebral arteries form from the division of the basilar artery

• These arteries supply the posterior cerebrum Circle of Willis § Anterior and posterior blood supplies are united by small communicating

arterial branches § Result—complete circle of connecting blood vessels called cerebral arterial

circle or circle of Willis § Hepatic Portal Circulation

o Veins of hepatic portal circulation drain § Digestive organs § Spleen § Pancreas

o Hepatic portal vein carries this blood to the liver o Liver helps maintain proper glucose, fat, and protein concentrations in blood Hepatic

Portal Circulation o Major vessels of hepatic portal circulation

§ Inferior and superior mesenteric veins § Splenic vein § Left gastric vein

§ Pulse o Pressure wave of blood o Monitored at “pressure points” in arteries where pulse is easily palpated o Pulse averages 70–76 beats per minute at rest

§ Blood Pressure o Measurements by health professionals are made on the pressure in large arteries

§ Systolic—pressure at the peak of ventricular contraction § Diastolic—pressure when ventricles relax § Write systolic pressure first and diastolic last (120/80 mm Hg)

o Pressure in blood vessels decreases as distance from the heart increases

The Nervous System

Functions of the Nervous System § Sensory input—gathering information

§ To monitor changes occurring inside and outside the body § Changes = stimuli

§ Integration § To process and interpret sensory input and decide if action is needed Functions of the Nervous System

§ Motor output § A response to integrated stimuli § The response activates muscles or glands Structural Classification of the Nervous System

§ Central nervous system (CNS) § Brain § Spinal cord

§ Peripheral nervous system (PNS) § Nerves outside the brain and spinal cord

§ Spinal nerves § Cranial nerves

Functional Classification of the Peripheral Nervous System § Sensory (afferent) division

§ Nerve fibers that carry information to the central nervous system § Motor (efferent) division

§ Nerve fibers that carry impulses away from the central nervous system Organization of the Nervous System Functional Classification of the Peripheral Nervous System

§ Motor (efferent) division (continued) § Two subdivisions

§ Somatic nervous system = voluntary § Autonomic nervous system = involuntary

Nervous Tissue: Support Cells § Support cells in the CNS are grouped together as “neuroglia” § Function: to support, insulate, and protect neurons

Nervous Tissue: Support Cells § Astrocytes

§ Abundant, star-shaped cells § Brace neurons § Form barrier between capillaries and neurons § Control the chemical environment of

the brain § Microglia

§ Spiderlike phagocytes § Dispose of debris

§ Ependymal cells § Line cavities of the brain and spinal cord § Circulate cerebrospinal fluid

§ Oligodendrocytes § Wrap around nerve fibers in the central nervous system § Produce myelin sheaths

§ Satellite cells § Protect neuron cell bodies

§ Schwann cells § Form myelin sheath in the peripheral nervous system Nervous Tissue: Neurons

§ Neurons = nerve cells

§ Cells specialized to transmit messages § Major regions of neurons

§ Cell body—nucleus and metabolic center of the cell § Processes—fibers that extend from the cell body

§ Cell body § Nissl substance

§ Specialized rough endoplasmic reticulum § Neurofibrils

§ Intermediate cytoskeleton § Maintains cell shape

§ Cell body § Nucleus § Large nucleolus

§ Processes outside the cell body § Dendrites—conduct impulses toward the cell body § Axons—conduct impulses away from the cell body

§ Axons end in axonal terminals § Axonal terminals contain vesicles with neurotransmitters § Axonal terminals are separated from the next neuron by a gap

§ Synaptic cleft—gap between adjacent neurons § Synapse—junction between nerves

§ Myelin sheath—whitish, fatty material covering axons § Schwann cells—produce myelin sheaths in jelly roll–like fashion § Nodes of Ranvier—gaps in myelin sheath along the axon

Neuron Cell Body Location § Most neuron cell bodies are found in the central nervous system

§ Gray matter—cell bodies and unmyelinated fibers § Nuclei—clusters of cell bodies within the white matter of the central nervous system

§ Ganglia—collections of cell bodies outside the central nervous system Functional Classification of Neurons

§ Sensory (afferent) neurons § Carry impulses from the sensory receptors to the CNS

§ Cutaneous sense organs § Proprioceptors—detect stretch or tension

§ Motor (efferent) neurons § Carry impulses from the central nervous system to viscera, muscles, or glands Functional Classification of Neurons

§ Interneurons (association neurons) § Found in neural pathways in the central nervous system § Connect sensory and motor neurons Neuron Classification Structural Classification of Neurons

§ Multipolar neurons—many extensions from the cell body § Bipolar neurons—one axon and one dendrite § Unipolar neurons—have a short single process leaving the cell body

Functional Properties of Neurons § Irritability

§ Ability to respond to stimuli § Conductivity

§ Ability to transmit an impulse

Nerve Impulses § Resting neuron

§ The plasma membrane at rest is polarized § Fewer positive ions are inside the cell than outside the cell

§ Depolarization § A stimulus depolarizes the neuron’s membrane § A depolarized membrane allows sodium (Na+) to flow inside the membrane

§ The exchange of ions initiates an action potential in the neuron § Action potential

§ If the action potential (nerve impulse) starts, it is propagated over the entire axon § Impulses travel faster when fibers have a myelin sheath

§ Repolarization § Potassium ions rush out of the neuron after sodium ions rush in, which repolarizes the

membrane § The sodium-potassium pump, using ATP, restores the original configuration Transmission of a Signal at Synapses

§ Impulses are able to cross the synapse to another nerve § Neurotransmitter is released from a nerve’s axon terminal § The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter § An action potential is started in the dendrite The Reflex Arc

§ Reflex—rapid, predictable, and involuntary response to a stimulus § Occurs over pathways called reflex arcs

§ Reflex arc—direct route from a sensory neuron, to an interneuron, to an effector Simple Reflex Arc Types of Reflexes and Regulation

§ Somatic reflexes § Activation of skeletal muscles § Example: When you move your hand away from a hot stove Types of Reflexes and Regulation

§ Autonomic reflexes § Smooth muscle regulation § Heart and blood pressure regulation § Regulation of glands § Digestive system regulation

§ Patellar, or knee-jerk, reflex is an example of a two-neuron reflex arc Central Nervous System (CNS)

§ CNS develops from the embryonic neural tube § The neural tube becomes the brain and spinal cord § The opening of the neural tube becomes the ventricles

§ Four chambers within the brain § Filled with cerebrospinal fluid

Regions of the Brain § Cerebral hemispheres (cerebrum) § Diencephalon § Brain stem § Cerebellum § Cerebral Hemispheres (Cerebrum)

§ Paired (left and right) superior parts of the brain § Includes more than half of the brain mass

§ The surface is made of ridges (gyri) and grooves (sulci) § Lobes of the cerebrum

§ Fissures (deep grooves) divide the cerebrum into lobes § Surface lobes of the cerebrum

§ Frontal lobe § Parietal lobe § Occipital lobe § Temporal lobe

§ Specialized areas of the cerebrum § Primary somatic sensory area

§ Receives impulses from the body’s sensory receptors § Located in parietal lobe

§ Primary motor area § Sends impulses to skeletal muscles § Located in frontal lobe

§ Broca’s area § Involved in our ability to speak

§ Cerebral areas involved in special senses § Gustatory area (taste) § Visual area § Auditory area § Olfactory area

§ Interpretation areas of the cerebrum § Speech/language region § Language comprehension region § General interpretation area

§ Layers of the cerebrum § Gray matter—outer layer in the cerebral cortex composed mostly of neuron cell bodies § White matter—fiber tracts deep to the gray matter

§ Corpus callosum connects hemispheres § Basal nuclei—islands of gray matter buried within the white matter

Regions of the Brain: Diencephalon § Sits on top of the brain stem § Enclosed by the cerebral hemispheres § Made of three parts

§ Thalamus § Hypothalamus § Epithalamus

§ Thalamus § Surrounds the third ventricle § The relay station for sensory impulses § Transfers impulses to the correct part of the cortex for localization and interpretation

§ Hypothalamus § Under the thalamus § Important autonomic nervous system center

§ Helps regulate body temperature § Controls water balance § Regulates metabolism

§ Hypothalamus (continued) § An important part of the limbic system (emotions) § The pituitary gland is attached to the hypothalamus

§ Epithalamus § Forms the roof of the third ventricle § Houses the pineal body (an endocrine gland) § Includes the choroid plexus—forms cerebrospinal fluid Regions of the Brain: Brain Stem

§ Attaches to the spinal cord § Parts of the brain stem

§ Midbrain § Pons § Medulla oblongata

§ Midbrain § Mostly composed of tracts of nerve fibers § Has two bulging fiber tracts—

cerebral peduncles § Has four rounded protrusions—

corpora quadrigemina § Reflex centers for vision and hearing

§ Pons § The bulging center part of the brain stem § Mostly composed of fiber tracts § Includes nuclei involved in the control of breathing

§ Medulla Oblongata § The lowest part of the brain stem § Merges into the spinal cord § Includes important fiber tracts § Contains important control centers

§ Heart rate control § Blood pressure regulation § Breathing § Swallowing § Vomiting

§ Reticular Formation § Diffuse mass of gray matter along the brain stem § Involved in motor control of visceral organs § Reticular activating system (RAS) plays a role in awake/sleep cycles and consciousness Regions of the Brain: Reticular Formation of the Brain Stem Regions of the Brain: Cerebellum

§ Two hemispheres with convoluted surfaces § Provides involuntary coordination of body movements

Protection of the Central Nervous System § Scalp and skin § Skull and vertebral column § Meninges § Cerebrospinal fluid (CSF) § Blood-brain barrier

Meninges § Dura mater

§ Double-layered external covering § Periosteum—attached to inner surface of the skull § Meningeal layer—outer covering of the brain

§ Folds inward in several areas

Meninges § Arachnoid layer

§ Middle layer § Web-like

§ Pia mater § Internal layer § Clings to the surface of the brain Cerebrospinal Fluid (CSF)

§ Similar to blood plasma composition § Formed by the choroid plexus § Forms a watery cushion to protect the brain § Circulated in arachnoid space, ventricles, and central canal of the spinal cord

Ventricles and Location of the Cerebrospinal Fluid Hydrocephalus in a Newborn

§ Hydrocephalus § CSF accumulates and exerts pressure on the brain if not allowed to drain Blood-Brain Barrier

§ Includes the least permeable capillaries of the body § Excludes many potentially harmful substances § Useless as a barrier against some substances

§ Fats and fat soluble molecules § Respiratory gases § Alcohol § Nicotine § Anesthesia Traumatic Brain Injuries

§ Concussion § Slight brain injury § No permanent brain damage

§ Contusion § Nervous tissue destruction occurs § Nervous tissue does not regenerate

§ Cerebral edema § Swelling from the inflammatory response § May compress and kill brain tissue Cerebrovascular Accident (CVA)

§ Commonly called a stroke § The result of a ruptured blood vessel supplying a region of the brain § Brain tissue supplied with oxygen from that blood source dies § Loss of some functions or death may result

Alzheimer’s Disease § Progressive degenerative brain disease § Mostly seen in the elderly, but may begin in middle age § Structural changes in the brain include abnormal protein deposits and twisted fibers within

neurons § Victims experience memory loss, irritability, confusion, and ultimately, hallucinations and

death Spinal Cord

§ Extends from the foramen magnum of the skull to the first or second lumbar vertebra § 31 pairs of spinal nerves arise from the spinal cord

§ Cauda equina is a collection of spinal nerves at the inferior end Spinal Cord Anatomy

§ Internal gray matter is mostly cell bodies § Dorsal (posterior) horns § Anterior (ventral) horns § Gray matter surrounds the central canal

§ Central canal is filled with cerebrospinal fluid § Exterior white mater—conduction tracts

§ Dorsal, lateral, ventral columns Spinal Cord Anatomy

§ Meninges cover the spinal cord § Spinal nerves leave at the level of each vertebrae

§ Dorsal root § Associated with the dorsal root ganglia—collections of cell bodies outside the central

nervous system § Ventral root

§ Contains axons Pathways Between Brain and Spinal Cord Peripheral Nervous System (PNS)

§ Nerves and ganglia outside the central nervous system § Nerve = bundle of neuron fibers § Neuron fibers are bundled by connective tissue

PNS: Structure of a Nerve § Endoneurium surrounds each fiber § Groups of fibers are bound into fascicles by perineurium § Fascicles are bound together by epineurium

PNS: Classification of Nerves § Mixed nerves

§ Both sensory and motor fibers § Sensory (afferent) nerves

§ Carry impulses toward the CNS § Motor (efferent) nerves

§ Carry impulses away from the CNS PNS: Cranial Nerves

§ 12 pairs of nerves that mostly serve the head and neck § Only the pair of vagus nerves extend to thoracic and abdominal cavities § Most are mixed nerves, but three are sensory only § I Olfactory nerve—sensory for smell § II Optic nerve—sensory for vision § III Oculomotor nerve—motor fibers to eye muscles § IV Trochlear—motor fiber to eye muscles § V Trigeminal nerve—sensory for the face; motor fibers to chewing muscles § VI Abducens nerve—motor fibers to eye muscles § VII Facial nerve—sensory for taste; motor fibers to the face § VIII Vestibulocochlear nerve—sensory for balance and hearing § IX Glossopharyngeal nerve—sensory for taste; motor fibers to the pharynx § X Vagus nerves—sensory and motor fibers for pharynx, larynx, and viscera § XI Accessory nerve—motor fibers to neck and upper back § XII Hypoglossal nerve—motor fibers to tongue

PNS: Distribution of Cranial Nerves

PNS: Spinal Nerves § There is a pair of spinal nerves at the level of each vertebrae for a total of 31 pairs § Formed by the combination of the ventral and dorsal roots of the spinal cord § Named for the region from which they arise

PNS: Anatomy of Spinal Nerves § Spinal nerves divide soon after leaving the spinal cord

§ Dorsal rami—serve the skin and muscles of the posterior trunk § Ventral rami—form a complex of networks (plexus) for the anterior PNS: Spinal Nerve Plexuses PNS: Distribution of Major Peripheral Nerves of the Upper and Lower Limbs PNS: Autonomic Nervous System

§ Motor subdivision of the PNS § Consists only of motor nerves

§ Also known as the involuntary nervous system § Regulates activities of cardiac and smooth muscles and glands

§ Two subdivisions § Sympathetic division § Parasympathetic division PNS: Differences Between Somatic and Autonomic Nervous Systems

§ Nerves § Somatic: one motor neuron § Autonomic: preganglionic and postganglionic nerves

§ Effector organs § Somatic: skeletal muscle § Autonomic: smooth muscle, cardiac muscle, and glands

§ Neurotransmitters § Somatic: always use acetylcholine § Autonomic: use acetylcholine, epinephrine, or norepinephrine PNS: Comparison of Somatic and Autonomic Nervous Systems PNS: Anatomy of the Sympathetic Division

§ Originates from T1 through L2 § Ganglia are at the sympathetic trunk (near the spinal cord) § Short pre-ganglionic neuron and long post-ganglionic neuron transmit impulse from CNS to

the effector § Norepinephrine and epinephrine are neurotransmitters to the effector organs

PNS: Anatomy of the Parasympathetic Division § Originates from the brain stem and S1 through S4 § Terminal ganglia are at the effector organs § Always uses acetylcholine as a neurotransmitter

PNS: Autonomic Functioning § Sympathetic—“fight or flight”

§ Response to unusual stimulus § Takes over to increase activities § Remember as the “E” division

§ Exercise, excitement, emergency, and embarrassment § Parasympathetic—“housekeeping” activites

§ Conserves energy § Maintains daily necessary body functions § Remember as the “D” division

§ digestion, defecation, and diuresis

Effects of the Sympathetic and Parasympathetic Divisions of the ANS

The Respiratory System Organs of the Respiratory System

§ Nose § Pharynx § Larynx § Trachea § Bronchi § Lungs—alveoli

Functions of the Respiratory System § Gas exchanges between the blood and external environment

§ Occurs in the alveoli of the lungs § Passageways to the lungs purify, humidify, and warm the incoming air

The Nose § Only externally visible part of the respiratory system § Air enters the nose through the external nostrils (nares) § Interior of the nose consists of a nasal cavity divided by a nasal septum

Upper Respiratory Tract Anatomy of the Nasal Cavity

§ Olfactory receptors are located in the mucosa on the superior surface § The rest of the cavity is lined with respiratory mucosa that

§ Moisten air § Trap incoming foreign particles Anatomy of the Nasal Cavity

§ Lateral walls have projections called conchae § Increase surface area § Increase air turbulence within the nasal cavity

§ The nasal cavity is separated from the oral cavity by the palate § Anterior hard palate (bone) § Posterior soft palate (muscle) Paranasal Sinuses

§ Cavities within bones surrounding the nasal cavity are called sinuses § Sinuses are located in the following bones

§ Frontal bone § Sphenoid bone § Ethmoid bone § Maxillary bone Upper Respiratory Tract—Paranasal Sinuses

§ Function of the sinuses § Lighten the skull § Act as resonance chambers for speech § Produce mucus that drains into the nasal cavity Pharynx (Throat)

§ Muscular passage from nasal cavity to larynx § Three regions of the pharynx

§ Nasopharynx—superior region behind nasal cavity § Oropharynx—middle region behind mouth

§ Laryngopharynx—inferior region attached to larynx § The oropharynx and laryngopharynx are common passageways for air and food

Structures of the Pharynx § Pharyngotympanic tubes open into the nasopharynx § Tonsils of the pharynx

§ Pharyngeal tonsil (adenoids) are located in the nasopharynx § Palatine tonsils are located in the oropharynx § Lingual tonsils are found at the base of the tongue Upper Respiratory Tract: Pharynx Larynx (Voice Box)

§ Routes air and food into proper channels § Plays a role in speech § Made of eight rigid hyaline cartilages and a spoon-shaped flap of elastic cartilage (epiglottis)

Structures of the Larynx § Thyroid cartilage

§ Largest of the hyaline cartilages § Protrudes anteriorly (Adam’s apple)

§ Epiglottis § Protects the superior opening of the larynx § Routes food to the esophagus and air toward the trachea § When swallowing, the epiglottis rises and forms a lid over the opening of the larynx

§ Vocal folds (true vocal cords) § Vibrate with expelled air to create sound (speech)

§ Glottis—opening between vocal cords Upper Respiratory Tract: Larynx Trachea (Windpipe)

§ Four-inch-long tube that connects larynx with bronchi § Walls are reinforced with C-shaped hyaline cartilage § Lined with ciliated mucosa

§ Beat continuously in the opposite direction of incoming air § Expel mucus loaded with dust and other debris away from lungs Main (Primary) Bronchi

§ Formed by division of the trachea § Enters the lung at the hilum (medial depression) § Right bronchus is wider, shorter, and straighter than left § Bronchi subdivide into smaller and smaller branches

Main Bronchi Lungs

§ Occupy most of the thoracic cavity § Heart occupies central portion called mediastinum

§ Apex is near the clavicle (superior portion) § Base rests on the diaphragm (inferior portion) § Each lung is divided into lobes by fissures

§ Left lung—two lobes § Right lung—three lobes Coverings of the Lungs

§ Serosa covers the outer surface of the lungs § Pulmonary (visceral) pleura covers the lung surface § Parietal pleura lines the walls of the thoracic cavity

§ Pleural fluid fills the area between layers of pleura to allow gliding

§ These two pleural layers resist being pulled apart Lungs Bronchial (Respiratory) Tree Divisions

§ All but the smallest of these passageways have reinforcing cartilage in their walls § Primary bronchi § Secondary bronchi § Tertiary bronchi § Bronchioles § Terminal bronchioles Bronchial (Respiratory) Tree Divisions Respiratory Zone

§ Structures § Respiratory bronchioles § Alveolar ducts § Alveolar sacs § Alveoli (air sacs)

§ Site of gas exchange = alveoli only Respiratory Membrane (Air-Blood Barrier)

§ Thin squamous epithelial layer lines alveolar walls § Alveolar pores connect neighboring air sacs § Pulmonary capillaries cover external surfaces of alveoli § On one side of the membrane is air and on the other side is blood flowing past

Gas Exchange § Gas crosses the respiratory membrane by diffusion

§ Oxygen enters the blood § Carbon dioxide enters the alveoli

§ Alveolar macrophages (“dust cells”) add protection by picking up bacteria, carbon particles, and other debris

§ Surfactant (a lipid molecule) coats gas-exposed alveolar surfaces Four Events of Respiration

§ Pulmonary ventilation—moving air in and out of the lungs (commonly called breathing) § External respiration—gas exchange between pulmonary blood and alveoli

§ Oxygen is loaded into the blood § Carbon dioxide is unloaded from the blood External Respiration Four Events of Respiration

§ Respiratory gas transport—transport of oxygen and carbon dioxide via the bloodstream § Internal respiration—gas exchange between blood and tissue cells in systemic capillaries

Mechanics of Breathing (Pulmonary Ventilation) § Completely mechanical process that depends on volume changes in the thoracic cavity § Volume changes lead to pressure changes, which lead to the flow of gases to equalize

pressure Mechanics of Breathing (Pulmonary Ventilation)

§ Two phases § Inspiration = inhalation

§ flow of air into lungs § Expiration = exhalation

§ air leaving lungs Inspiration

§ Diaphragm and external intercostal muscles contract § The size of the thoracic cavity increases § External air is pulled into the lungs due to

§ Increase in intrapulmonary volume § Decrease in gas pressure Expiration

§ Largely a passive process which depends on natural lung elasticity § As muscles relax, air is pushed out of the lungs due to

§ Decrease in intrapulmonary volume § Increase in gas pressure

§ Forced expiration can occur mostly by contracting internal intercostal muscles to depress the rib cage

Pressure Differences in the Thoracic Cavity § Normal pressure within the pleural space is always negative (intrapleural pressure) § Differences in lung and pleural space pressures keep lungs from collapsing

Nonrespiratory Air (Gas) Movements § Can be caused by reflexes or voluntary actions § Examples:

§ Cough and sneeze—clears lungs of debris § Crying—emotionally induced mechanism § Laughing—similar to crying § Hiccup—sudden inspirations § Yawn—very deep inspiration Respiratory Volumes and Capacities

§ Normal breathing moves about 500 mL of air with each breath § This respiratory volume is tidal volume (TV)

§ Many factors that affect respiratory capacity § A person’s size § Sex § Age § Physical condition Respiratory Volumes and Capacities

§ Inspiratory reserve volume (IRV) § Amount of air that can be taken in forcibly over the tidal volume § Usually between 2100 and 3200 mL

§ Expiratory reserve volume (ERV) § Amount of air that can be forcibly exhaled § Approximately 1200 mL Respiratory Volumes and Capacities

§ Residual volume § Air remaining in lung after expiration § About 1200 ml Respiratory Volumes and Capacities

§ Vital capacity § The total amount of exchangeable air § Vital capacity = TV + IRV + ERV § Dead space volume

§ Air that remains in conducting zone and never reaches alveoli § About 150 mL

Respiratory Volumes and Capacities

§ Functional volume § Air that actually reaches the respiratory zone § Usually about 350 mL

§ Respiratory capacities are measured with a spirometer Respiratory Volumes Respiratory Sounds

§ Sounds are monitored with a stethoscope § Two recognizable sounds can be heard with a stethoscope

§ Bronchial sounds—produced by air rushing through trachea and bronchi § Vesicular breathing sounds—soft sounds of air filling alveoli External Respiration

§ Oxygen loaded into the blood § The alveoli always have more oxygen than the blood § Oxygen moves by diffusion towards the area of lower concentration § Pulmonary capillary blood gains oxygen External Respiration

§ Carbon dioxide unloaded out of the blood § Blood returning from tissues has higher concentrations of carbon dioxide than air in the

alveoli § Pulmonary capillary blood gives up carbon dioxide to be exhaled

§ Blood leaving the lungs is oxygen-rich and carbon dioxide-poor External Respiration Gas Transport in the Blood

§ Oxygen transport in the blood § Most oxygen attached to hemoglobin to form oxyhemoglobin (HbO2) § A small dissolved amount is carried in the plasma Gas Transport in the Blood

§ Carbon dioxide transport in the blood § Most is transported in the plasma as bicarbonate ion (HCO3

–) § A small amount is carried inside red blood cells on hemoglobin, but at different binding

sites than those of oxygen Gas Transport in the Blood

§ For carbon dioxide to diffuse out of blood into the alveoli, it must be released from its bicarbonate form: § Bicarbonate ions enter RBC § Combine with hydrogen ions § Form carbonic acid (H2CO3) § Carbonic acid splits to form water + CO2 § Carbon dioxide diffuses from blood into alveoli Gas Transport in Blood Internal Respiration

§ Exchange of gases between blood and body cells § An opposite reaction to what occurs in the lungs

§ Carbon dioxide diffuses out of tissue to blood (called loading) § Oxygen diffuses from blood into tissue (called unloading) External Respiration, Gas Transport, and Internal Respiration Summary Neural Regulation of Respiration

§ Activity of respiratory muscles is transmitted to and from the brain by phrenic and intercostal nerves

§ Neural centers that control rate and depth are located in the medulla and pons § Medulla—sets basic rhythm of breathing and contains a pacemaker called the self-

exciting inspiratory center § Pons—appears to smooth out respiratory rate Neural Regulation of Respiration

§ Normal respiratory rate (eupnea) § 12–15 respirations per minute

§ Hyperpnea § Increased respiratory rate often due to extra oxygen needs Neural Regulation of Respiration Non-Neural Factors Influencing Respiratory Rate and Depth

§ Physical factors § Increased body temperature § Exercise § Talking § Coughing

§ Emotional factors Non-Neural Factors Influencing Respiratory Rate and Depth

§ Chemical factors: CO2 levels § The body’s need to rid itself of CO2 is the most important stimulus § Increased levels of carbon dioxide (and thus, a decreased or acidic pH) in the blood

increase the rate and depth of breathing § Changes in carbon dioxide act directly on the medulla oblongata Non-Neural Factors Influencing Respiratory Rate and Depth

§ Chemical factors: oxygen levels § Changes in oxygen concentration in the blood are detected by chemoreceptors in the

aorta and common carotid artery § Information is sent to the medulla Hyperventilation and Hypoventilation

§ Hyperventilation § Results from increased CO2 in the blood (acidosis) § Breathing becomes deeper and more rapid § Blows off more CO2 to restore normal blood pH Hyperventilation and Hypoventilation

§ Hypoventilation § Results when blood becomes alkaline (alkalosis) § Extremely slow or shallow breathing § Allows CO2 to accumulate in the blood § Those infected will ultimately develop respiratory failure

The Digestive System and Body Metabolism The Digestive System Functions

§ Ingestion—taking in food § Digestion—breaking food down both physically and chemically § Absorption—movement of nutrients into the bloodstream § Defecation—rids the body of indigestible waste

Organs of the Digestive System § Two main groups

§ Alimentary canal (gastrointestinal or GI tract)—continuous coiled hollow tube

§ Accessory digestive organs Organs of the Digestive System Organs of the Alimentary Canal

§ Mouth § Pharynx § Esophagus § Stomach § Small intestine § Large intestine § Anus

Mouth (Oral Cavity) Anatomy § Lips (labia)—protect the anterior opening § Cheeks—form the lateral walls § Hard palate—forms the anterior roof § Soft palate—forms the posterior roof § Uvula—fleshy projection of the soft palate

Mouth (Oral Cavity) Anatomy § Vestibule—space between lips externally and teeth and gums internally § Oral cavity proper—area contained by the teeth § Tongue—attached at hyoid bone and styloid processes of the skull, and by the lingual

frenulum to the floor of the mouth § Tonsils

§ Palatine § Lingual Mouth Physiology

§ Mastication (chewing) of food § Mixing masticated food with saliva § Initiation of swallowing by the tongue § Allows for the sense of taste

Pharynx Anatomy § Nasopharynx—not part of the digestive system § Oropharynx—posterior to oral cavity § Laryngopharynx—below the oropharynx and connected to the esophagus

Pharynx Physiology § Serves as a passageway for air and food § Food is propelled to the esophagus by two muscle layers

§ Longitudinal inner layer § Circular outer layer

§ Food movement is by alternating contractions of the muscle layers (peristalsis) Esophagus Anatomy and Physiology

§ Anatomy § About 10 inches long § Runs from pharynx to stomach through the diaphragm

§ Physiology § Conducts food by peristalsis (slow rhythmic squeezing) § Passageway for food only (respiratory system branches off after the pharynx) Layers of Alimentary Canal Organs

§ Four layers § Mucosa § Submucosa

§ Muscularis externa § Serosa Layers of Alimentary Canal Organs

§ Mucosa § Innermost, moist membrane consisting of

§ Surface epithelium § Small amount of connective tissue

(lamina propria) § Small smooth muscle layer

Layers of Alimentary Canal Organs § Submucosa

§ Just beneath the mucosa § Soft connective tissue with blood vessels, nerve endings, and lymphatics Layers of Alimentary Canal Organs

§ Muscularis externa—smooth muscle § Inner circular layer § Outer longitudinal layer

§ Serosa—outermost layer of the wall contains fluid-producing cells § Visceral peritoneum—outermost layer that is continuous with the innermost layer § Parietal peritoneum—innermost layer that lines the abdominopelvic cavity Layers of Alimentary Canal Organs Alimentary Canal Nerve Plexuses

§ Two important nerve plexuses serve the alimentary canal § Both are part of the autonomic nervous system

§ Submucosal nerve plexus § Myenteric nerve plexus

§ Function is to regulate mobility and secretory activity of the GI tract organs Stomach Anatomy

§ Located on the left side of the abdominal cavity § Food enters at the cardioesophageal sphincter § Food empties into the small intestine at the pyloric sphincter (valve)

Stomach Anatomy § Regions of the stomach

§ Cardiac region—near the heart § Fundus—expanded portion lateral to the cardiac region § Body—midportion § Pylorus—funnel-shaped terminal end Stomach Anatomy

§ Rugae—internal folds of the mucosa § External regions

§ Lesser curvature—concave medial surface § Greater curvature—convex lateral surface Stomach Anatomy

§ Layers of peritoneum attached to the stomach § Lesser omentum—attaches the liver to the lesser curvature § Greater omentum—attaches the greater curvature to the posterior body wall

§ Contains fat to insulate, cushion, and protect abdominal organs § Has lymph nodules containing macrophages

Stomach Physiology § Temporary storage tank for food

§ Site of food breakdown § Chemical breakdown of protein begins § Delivers chyme (processed food) to the small intestine

Structure of the Stomach Mucosa § Mucosa is simple columnar epithelium § Mucous neck cells—produce a sticky alkaline mucus § Gastric glands—situated in gastric pits and secrete gastric juice § Chief cells—produce protein-digesting enzymes (pepsinogens) § Parietal cells—produce hydrochloric acid § Enteroendocrine cells—produce gastrin

Small Intestine § The body’s major digestive organ § Site of nutrient absorption into the blood § Muscular tube extending from the pyloric sphincter to the ileocecal valve § Suspended from the posterior abdominal wall by the mesentery

Subdivisions of the Small Intestine § Duodenum

§ Attached to the stomach § Curves around the head of the pancreas

§ Jejunum § Attaches anteriorly to the duodenum

§ Ileum § Extends from jejunum to large intestine Chemical Digestion in the Small Intestine

§ Chemical digestion begins in the small intestine § Enzymes are produced by

§ Intestinal cells § Pancreas

§ Pancreatic ducts carry enzymes to the small intestine § Bile, formed by the liver, enters via the bile duct Chemical Digestion in the Small Intestine Small Intestine Anatomy

§ Three structural modifications that increase surface area § Microvilli—tiny projections of the plasma membrane (create a brush border appearance) § Villi—fingerlike structures formed by the mucosa § Circular folds (plicae circulares)—deep folds of mucosa and submucosa Large Intestine

§ Larger in diameter, but shorter in length, than the small intestine § Frames the internal abdomen

Large Intestine Anatomy § Cecum—saclike first part of the large intestine § Appendix

§ Accumulation of lymphatic tissue that sometimes becomes inflamed (appendicitis) § Hangs from the cecum Large Intestine Large Intestine Anatomy

§ Colon § Ascending—travels up right side of abdomen § Transverse—travels across the abdominal cavity § Descending—travels down the left side

§ Sigmoid—enters the pelvis § Rectum and anal canal—also in pelvis

Large Intestine Large Intestine Anatomy

§ Anus—opening of the large intestine § External anal sphincter—formed by skeletal muscle and under voluntary control § Internal involuntary sphincter—formed by smooth muscle § These sphincters are normally closed except during defecation Large Intestine Large Intestine Anatomy

§ No villi present § Goblet cells produce alkaline mucus which lubricates the passage of feces § Muscularis externa layer is reduced to three bands of muscle called teniae coli § These bands cause the wall to pucker into haustra (pocketlike sacs)

Accessory Digestive Organs § Teeth § Salivary glands § Pancreas § Liver § Gallbladder

Teeth § Function is to masticate (chew) food § Humans have two sets of teeth

§ Deciduous (baby or “milk”) teeth § 20 teeth are fully formed by age two Teeth

§ Permanent teeth § Replace deciduous teeth between the ages of 6 and 12 § A full set is 32 teeth, but some people do not have wisdom teeth (third molars) § If they do emerge, the wisdom teeth appear between ages of 17 and 25 Classification of Teeth

§ Incisors—cutting § Canines—tearing or piercing § Premolars—grinding § Molars—grinding

Human Deciduous and Permanent Teeth Regions of a Tooth

§ Crown—exposed part § Enamel—hardest substance in the body § Dentin—found deep to the enamel and forms the bulk of the tooth § Pulp cavity—contains connective tissue, blood vessels, and nerve fibers § Root canal—where the pulp cavity extends into the root Regions of a Tooth

§ Neck § Region in contact with the gum § Connects crown to root

§ Root § Cementum—covers outer surface and attaches the tooth to the periodontal membrane Regions of a Tooth

Salivary Glands § Three pairs of salivary glands empty secretions into the mouth

§ Parotid glands § Submandibular glands § Sublingual glands Salivary Glands Saliva

§ Mixture of mucus and serous fluids § Helps to form a food bolus § Contains salivary amylase to begin starch digestion § Dissolves chemicals so they can be tasted

Pancreas § Found posterior to the parietal peritoneum § Extends across the abdomen from spleen to duodenum

Pancreas § Produces a wide spectrum of digestive enzymes that break down all categories of food § Enzymes are secreted into the duodenum § Alkaline fluid introduced with enzymes neutralizes acidic chyme coming from stomach § Hormones produced by the pancreas

§ Insulin § Glucagon Liver

§ Largest gland in the body § Located on the right side of the body under the diaphragm § Consists of four lobes suspended from the diaphragm and abdominal wall by the falciform

ligament § Connected to the gallbladder via the common hepatic duct

Bile § Produced by cells in the liver § Composition is

§ Bile salts § Bile pigments (mostly bilirubin from the breakdown of hemoglobin) § Cholesterol § Phospholipids § Electrolytes Bile

§ Function—emulsify fats by physically breaking large fat globules into smaller ones Gallbladder

§ Sac found in hollow fossa of liver § When no digestion is occurring, bile backs up the cystic duct for storage in the gallbladder § When digestion of fatty food is occurring, bile is introduced into the duodenum from the

gallbladder § Gallstones are crystallized cholesterol which can cause blockages

Functions of the Digestive System § Ingestion—getting food into the mouth § Propulsion—moving foods from one region of the digestive system to another

§ Peristalsis—alternating waves of contraction and relaxation that squeezes food along the GI tract

§ Segmentation—moving materials back and forth to aid with mixing in the small intestine Functions of the Digestive System

§ Food breakdown as mechanical digestion § Examples:

§ Mixing food in the mouth by the tongue § Churning food in the stomach § Segmentation in the small intestine

§ Mechanical digestion prepares food for further degradation by enzymes Functions of the Digestive System

§ Food breakdown as chemical digestion § Enzymes break down food molecules into their building blocks § Each major food group uses different enzymes

§ Carbohydrates are broken to simple sugars § Proteins are broken to amino acids § Fats are broken to fatty acids and alcohols

Functions of the Digestive System § Absorption

§ End products of digestion are absorbed in the blood or lymph § Food must enter mucosal cells and then into blood or lymph capillaries

§ Defecation § Elimination of indigestible substances from the GI tract in the form of feces Functions of the Digestive System Control of Digestive Activity

§ Mostly controlled by reflexes via the parasympathetic division § Chemical and mechanical receptors are located in organ walls that trigger reflexes

Control of Digestive Activity § Stimuli include

§ Stretch of the organ § pH of the contents § Presence of breakdown products

§ Reflexes include § Activation or inhibition of glandular secretions § Smooth muscle activity Digestive Activities of the Mouth

§ Mechanical breakdown § Food is physically broken down by chewing

§ Chemical digestion § Food is mixed with saliva § Starch is broken down into maltose by salivary amylase Activities of the Pharynx and Esophagus

§ These organs have no digestive function § Serve as passageways to the stomach

Deglutition (Swallowing) § Buccal phase

§ Voluntary § Occurs in the mouth § Food is formed into a bolus § The bolus is forced into the pharynx by the tongue Deglutition (Swallowing)

§ Pharyngeal-esophageal phase § Involuntary transport of the bolus § All passageways except to the stomach are blocked

§ Tongue blocks off the mouth § Soft palate (uvula) blocks the nasopharynx § Epiglottis blocks the larynx

§ Peristalsis moves the bolus toward the stomach § The cardioesophageal sphincter is opened when food presses against it Food Breakdown in the Stomach

§ Gastric juice is regulated by neural and hormonal factors § Presence of food or rising pH causes the release of the hormone gastrin § Gastrin causes stomach glands to produce

§ Protein-digesting enzymes § Mucus § Hydrochloric acid Food Breakdown in the Stomach

§ Hydrochloric acid makes the stomach contents very acidic § Acidic pH

§ Activates pepsinogen to pepsin for protein digestion § Provides a hostile environment for microorganisms Digestion and Absorption in the Stomach

§ Protein digestion enzymes § Pepsin—an active protein-digesting enzyme § Rennin—works on digesting milk protein in infants, not adults

§ Alcohol and aspirin are the only items absorbed in the stomach Propulsion in the Stomach

§ Food must first be well mixed § Rippling peristalsis occurs in the lower stomach § The pylorus meters out chyme into the small intestine (30 mL at a time) § The stomach empties in 4–6 hours

Digestion in the Small Intestine § Enzymes from the brush border function to

§ Break double sugars into simple sugars § Complete some protein digestion Digestion in the Small Intestine

§ Pancreatic enzymes play the major digestive function § Help complete digestion of starch (pancreatic amylase) § Carry out about half of all protein digestion § Digest fats using lipases from the pancreas § Digest nucleic acids using nucleases

§ Alkaline content neutralizes acidic chyme Regulation of Pancreatic Juice Secretion

§ Release of pancreatic juice into the duodenum is stimulated by § Vagus nerve § Local hormones

§ Secretin § Cholecystokinin (CCK)

§ Hormones travel the blood to stimulate the pancreas to release enzyme- and bicarbonate-rich product

Regulation of Pancreatic Juice Secretion § Secretin causes the liver to increase bile output § CCK causes the gallbladder to release stored bile

§ Bile is necessary for fat absorption and absorption of fat-soluble vitamins (K, D, A)

Hormones and Hormonelike Products that Act in Digestion Absorption in the Small Intestine

§ Water is absorbed along the length of the small intestine § End products of digestion

§ Most substances are absorbed by active transport through cell membranes § Lipids are absorbed by diffusion

§ Substances are transported to the liver by the hepatic portal vein or lymph Propulsion in the Small Intestine

§ Peristalsis is the major means of moving food § Segmental movements

§ Mix chyme with digestive juices § Aid in propelling food Segmentation Food Breakdown and Absorption in the Large Intestine

§ No digestive enzymes are produced § Resident bacteria digest remaining nutrients

§ Produce some vitamin K and B § Release gases

§ Water and vitamins K and B are absorbed § Remaining materials are eliminated via feces

Food Breakdown and Absorption in the Large Intestine § Feces contains

§ Undigested food residues § Mucus § Bacteria § Water Propulsion in the Large Intestine

§ Sluggish peristalsis § Mass movements

§ Slow, powerful movements § Occur three to four times per day

§ Presence of feces in the rectum causes a defecation reflex § Internal anal sphincter is relaxed § Defecation occurs with relaxation of the voluntary (external) anal sphincter Nutrition

§ Nutrient—substance used by the body for growth, maintenance, and repair § Major nutrients

§ Carbohydrates § Lipids § Proteins § Water

§ Minor nutrients § Vitamins § Minerals Five Basic Food Groups and Some of Their Major Nutrients USDA Food Guide Pyramid Dietary Sources of Major Nutrients

§ Carbohydrates § Most are derived from plants § Exceptions: lactose from milk and small amounts of glycogens from meats

§ Lipids § Saturated fats from animal products § Unsaturated fats from nuts, seeds, and vegetable oils § Cholesterol from egg yolk, meats, and milk products Dietary Sources of Major Nutrients

§ Proteins § Complete proteins—contain all essential amino acids

§ Most are from animal products § Legumes and beans also have proteins, but are incomplete

§ Vitamins § Most vitamins are used as coenzymes § Found in all major food groups Dietary Sources of Major Nutrients

§ Minerals § Play many roles in the body § Most mineral-rich foods are vegetables, legumes, milk, and some meats Metabolism

§ Chemical reactions necessary to maintain life § Catabolism—substances are broken down to simpler substances; energy is released § Anabolism—larger molecules are built from smaller ones Carbohydrate Metabolism

§ Carbohydrates are the body’s preferred source to produce cellular energy (ATP) § Glucose (blood sugar) is the major breakdown product and fuel to make ATP

Cellular Respiration § Oxygen-using events take place within the cell to create ATP from ADP § Carbon leaves cells as carbon dioxide (CO2) § Hydrogen atoms are combined with oxygen to form water § Energy produced by these reactions adds a phosphorus to ADP to produce ATP § ATP can be broken down to release energy for cellular use

Special Senses The Senses

§ General senses of touch § Temperature § Pressure § Pain The Senses

§ Special senses § Smell § Taste § Sight § Hearing § Equilibrium The Eye and Vision

§ 70% of all sensory receptors are in the eyes § Each eye has over a million nerve fibers § Protection for the eye

§ Most of the eye is enclosed in a bony orbit § A cushion of fat surrounds most of the eye Accessory Structures of the Eye

§ Eyelids and eyelashes § Conjunctiva § Lacrimal apparatus § Extrinsic eye muscles

Accessory Structures of the Eye § Eyelids and eyelashes

§ Tarsal glands lubricate the eye § Ciliary glands are located between the eyelashes

§ Conjunctiva § Membrane that lines the eyelids § Connects to the surface of the eye § Secretes mucus to lubricate the eye

§ Lacrimal apparatus § Lacrimal gland—produces lacrimal fluid § Lacrimal canals—drain lacrimal fluid from eyes § Lacrimal sac—provides passage of lacrimal fluid towards nasal cavity § Nasolacrimal duct—empties lacrimal fluid into the nasal cavity

§ Function of the lacrimal apparatus § Protects, moistens, and lubricates the eye § Empties into the nasal cavity

§ Properties of lacrimal fluid § Dilute salt solution (tears) § Contains antibodies and lysozyme

§ Extrinsic eye muscles § Six muscles attach to the outer surface of the eye § Produce eye movements Structure of the Eye

§ Layers forming the wall of the eyeball § Fibrous layer

§ Outside layer § Vascular layer

§ Middle layer § Sensory layer

§ Inside layer Structure of the Eye: The Fibrous Layer

§ Sclera § White connective tissue layer § Seen anteriorly as the “white of the eye”

§ Cornea § Transparent, central anterior portion § Allows for light to pass through § Repairs itself easily § The only human tissue that can be transplanted without fear of rejection Structure of the Eye: Vascular Layer

§ Choroid is a blood-rich nutritive layer in the posterior of the eye § Pigment prevents light from scattering

§ Modified anteriorly into two structures § Ciliary body—smooth muscle attached to lens § Iris—regulates amount of light entering eye

§ Pigmented layer that gives eye color § Pupil—rounded opening in the iris

Structure of the Eye: Sensory Layer § Retina contains two layers

§ Outer pigmented layer § Inner neural layer

§ Contains receptor cells (photoreceptors) § Rods § Cones

§ Signals pass from photoreceptors via a two-neuron chain § Bipolar neurons § Ganglion cells

§ Signals leave the retina toward the brain through the optic nerve § Optic disc (blind spot) is where the optic nerve leaves the eyeball

§ Cannot see images focused on the optic disc § Neurons of the retina and vision

§ Rods § Most are found towards the edges of the retina § Allow dim light vision and peripheral vision § All perception is in gray tones

§ Neurons of the retina and vision § Cones

§ Allow for detailed color vision § Densest in the center of the retina § Fovea centralis—area of the retina with only cones

§ No photoreceptor cells are at the optic disc, or blind spot § Cone sensitivity

§ Three types of cones § Different cones are sensitive to different wavelengths § Color blindness is the result of the lack of one cone type Sensitivities of Cones to Different Wavelengths Lens

§ Biconvex crystal-like structure § Held in place by a suspensory ligament attached to the ciliary body

Lens § Cataracts result when the lens becomes hard and opaque with age

§ Vision becomes hazy and distorted § Eventually causes blindness in affected eye Two Segments, or Chambers, of the Eye

§ Anterior (aqueous) segment § Anterior to the lens § Contains aqueous humor

§ Posterior (vitreous) segment § Posterior to the lens § Contains vitreous humor Anterior Segment

§ Aqueous humor § Watery fluid found between lens and cornea § Similar to blood plasma § Helps maintain intraocular pressure § Provides nutrients for the lens and cornea § Reabsorbed into venous blood through the scleral venous sinus, or canal of Schlemm

Posterior Segment § Vitreous humor

§ Gel-like substance posterior to the lens § Prevents the eye from collapsing § Helps maintain intraocular pressure Ophthalmoscope

§ Instrument used to illuminate the interior of the eyeball § Can detect diabetes, arteriosclerosis, degeneration of the optic nerve and retina

Posterior Wall of Retina as Seen with Ophthalmoscope Pathway of Light Through the Eye

§ Light must be focused to a point on the retina for optimal vision § The eye is set for distance vision

(over 20 feet away) § Accommodation—the lens must change shape to focus on closer objects (less than 20 feet

away) Pathway of Light Through the Eye

§ Image formed on the retina is a real image § Real images are

§ Reversed from left to right § Upside down § Smaller than the object Images Formed on the Retina Visual Fields and Visual Pathways

§ Optic chiasma § Location where the optic nerves cross § Fibers from the medial side of each eye cross over to the opposite side of the brain

§ Optic tracts § Contain fibers from the lateral side of the eye on the same side and the medial side of the

opposite eye Visual Fields and Visual Pathways Eye Reflexes

§ Internal muscles are controlled by the autonomic nervous system § Bright light causes pupils to constrict through action of radial, circular, and ciliary muscles § Viewing close objects causes accommodation

§ External muscles control eye movement to follow objects § Viewing close objects causes convergence (eyes moving medially)

A Closer Look § Emmetropia—eye focuses images correctly on the retina § Myopia (nearsighted)

§ Distant objects appear blurry § Light from those objects fails to reach the retina and are focused in front of it § Results from an eyeball that is too long A Closer Look

§ Hyperopia (farsighted) § Near objects are blurry while distant objects are clear § Distant objects are focused behind the retina § Results from an eyeball that is too short or from a “lazy lens” A Closer Look

§ Astigmatism

§ Images are blurry § Results from light focusing as lines, not points, on the retina due to unequal curvatures of

the cornea or lens Homeostatic Imbalances of the Eyes

§ Night blindness—inhibited rod function that hinders the ability to see at night § Color blindness—genetic conditions that result in the inability to see certain colors

§ Due to the lack of one type of cone (partial color blindness) § Cataracts—when lens becomes hard and opaque, our vision becomes hazy and distorted

Homeostatic Imbalances of the Eyes § Glaucoma—can cause blindness due to increasing pressure within the eye § Hemianopia—loss of the same side of the visual field of both eyes; results from damage to

the visual cortex on one side only The Ear

§ Houses two senses § Hearing § Equilibrium (balance)

§ Receptors are mechanoreceptors § Different organs house receptors for each sense

Anatomy of the Ear § The ear is divided into three areas

§ External (outer) ear § Middle ear (tympanic cavity) § Inner ear (bony labyrinth) The External Ear

§ Involved in hearing only § Structures of the external ear

§ Auricle (pinna) § External acoustic meatus (auditory canal)

§ Narrow chamber in the temporal bone § Lined with skin and ceruminous (wax) glands § Ends at the tympanic membrane

The Middle Ear (Tympanic Cavity) § Air-filled cavity within the temporal bone § Only involved in the sense of hearing § Two tubes are associated with the inner ear

§ The opening from the auditory canal is covered by the tympanic membrane § The auditory tube connecting the middle ear with the throat

§ Allows for equalizing pressure during yawning or swallowing § This tube is otherwise collapsed

Bones of the Middle Ear (Tympanic Cavity) § Three bones (ossicles) span the cavity

§ Malleus (hammer) § Incus (anvil) § Stapes (stirrip)

§ Function § Vibrations from eardrum move the malleus à anvil à stirrup à inner ear Anatomy of the Ear Inner Ear or Bony Labyrinth

§ Includes sense organs for hearing and balance § Filled with perilymph

§ A maze of bony chambers within the temporal bone § Cochlea § Vestibule § Semicircular canals Organs of Equilibrium

§ Equilibrium receptors of the inner ear are called the vestibular apparatus § Vestibular apparatus has two functional parts

§ Static equilibrium § Dynamic equilibrium Static Equilibrium

§ Maculae—receptors in the vestibule § Report on the position of the head § Send information via the vestibular nerve

§ Anatomy of the maculae § Hair cells are embedded in the otolithic membrane § Otoliths (tiny stones) float in a gel around the hair cells § Movements cause otoliths to bend the hair cells Structure and Function of Maculae Dynamic Equilibrium

§ Crista ampullaris—receptors in the semicircular canals § Tuft of hair cells § Cupula (gelatinous cap) covers the hair cells Dynamic Equilibrium

§ Action of angular head movements § The cupula stimulates the hair cells § An impulse is sent via the vestibular nerve to the cerebellum Organs of Hearing

§ Organ of Corti § Located within the cochlea § Receptors = hair cells on the basilar membrane § Gel-like tectorial membrane is capable of bending hair cells § Cochlear nerve attached to hair cells transmits nerve impulses to auditory cortex on

temporal lobe Mechanism of Hearing

§ Vibrations from sound waves move tectorial membrane § Hair cells are bent by the membrane § An action potential starts in the cochlear nerve § Continued stimulation can lead to adaptation

Olfaction—The Sense of Smell § Olfactory receptors are in the roof of the nasal cavity

§ Neurons with long cilia § Chemicals must be dissolved in mucus for detection

§ Impulses are transmitted via the olfactory nerve § Interpretation of smells is made in the cortex

Olfactory Epithelium The Sense of Taste

§ Taste buds house the receptor organs § Location of taste buds

§ Most are on the tongue § Soft palate

§ Cheeks Taste Buds The Tongue and Taste

§ The tongue is covered with projections called papillae § Filiform papillae—sharp with no taste buds § Fungifiorm papillae—rounded with taste buds § Circumvallate papillae—large papillae with taste buds

§ Taste buds are found on the sides of papillae Structure of Taste Buds

§ Gustatory cells are the receptors § Have gustatory hairs (long microvilli) § Hairs are stimulated by chemicals dissolved in saliva

§ Impulses are carried to the gustatory complex by several cranial nerves because taste buds are found in different areas § Facial nerve § Glossopharyngeal nerve § Vagus nerve Taste Sensations

§ Sweet receptors (sugars) § Saccharine § Some amino acids

§ Sour receptors § Acids

§ Bitter receptors § Alkaloids

§ Salty receptors § Metal ions