chapter 20: tissues & organ systems
TRANSCRIPT
Chapter 20:Tissues & Organ Systems
The Importance of HomeostasisThe maintenance of a relatively constantinternal environment, i.e., homeostasis, isessential for life.
Temperature
Cellular conditions that need to be maintained within a narrow range include:
pH
concentrations of: minerals, nutrients, wastes
Negative FeedbackHomeostasis is largely maintained by what isknown as Negative Feedback:
• counteracting a change in body state torestore the original state
• sweating to cool an overheated bodye.g.
• releasing insulin to lower blood sugar
**various sensory systems in the body detectchanges and trigger negative feedback responses**
• accelerated breathing, pulse to increase oxygen
Organization of the Animal Body
Cells Tissues Organs Organ Systems
The 4 Basic Tissue Types
Epithelial Tissue
Connective Tissue
Muscle Tissue
Nerve Tissue
All tissues in the animal body fall into one of4 basic tissue types:
Epithelial TissueSheets of cells that line body surfaces, cavities:
skin; digestive, urinary,reproductive tracts;vessels; glands
Epithelial cells come in 3 basic shapes…
• cuboidal (cube-shaped)• squamos (flattened)
• columnar (elongated)…and in single or multiple layers:
simple or stratified epith.
simple squamous epithelium (lung)
simple cuboidal epithelium (kidney)
simple columnar epithelium (intestine)
stratified squamous epithelium(lining the esophagus)
dead cells
rapidly dividing
cells
stratified squamous epithelium(human skin)
Col
oriz
ed S
EM
Examples of Epithelial Tissue
Connective TissueTissue that supports, binds, “fills” or provides structure.
Connective Tissue (CT) comes in 3 basic types:Loose CT – underlies epithelium, loosely woven fibers,
“gel-like”
Fibrous or Dense CT – densely packed fibers as in tendons & ligaments
Specialized CT – bone, cartilage, blood & lymph,adipose (fat) tissue
• contains few cells, mostly extracellular matrix (ECM)
Cartilage-formingcells
Matrix
cartilage (end of a bone)
Centralcanal
Matrix
Bone-formingcells
bone
bloodloose connective tissue
(under the skin)
Collagenfibers
Cellnucleus
fibrous connective tissue (tendon) White blood
cells
Red bloodcell
Plasma
adipose tissue
Fatdroplets
Examples of Connective Tissue
Unit ofmusclecontraction Muscle
fiber
Nucleus
skeletal muscle
Nucleus
Musclefiber
Junction betweentwo cells
Muscle fiberNucleus
smooth muscle
cardiac muscle
Muscle TissueMade of cells that contract, comes in 3 types:
Skeletal Muscle (striated, voluntary – moves skeleton)Cardiac Muscle (striated, involuntary – heartbeat)Smooth Muscle (unstriated, involuntary – visceral org., vessels)
Nerve TissueTissue that transmits electrical signals.
Contains 2 basic cell types:Neurons – cells that generate, transmit electrical signals
Glial cells (glia)– metabolic support, insulation for neurons
neuron
Organs and Organ Systems
Organ systems = multiple organs that work together to perform a common function
• each tissue and organ has a distinct role
• skin, nails, hair each have different roles
e.g. – Integumentary System (skin, nails, etc)
• each contains multiple tissues (epithelium, connective tissue, muscle, nerve) with diff. roles
Organs = multiple tissues that comprise aphysically & functionally distinct structure
Organs are made of all Tissue TypesSmall intestine
(cut open)
Lumen
epithelial tissue(columnar epithelium)
connective tissue
smooth muscletissue (2 layers)
connective tissueepithelial tissue
Lumen
10 Major Organ Systems
The Circulatory System(blood & vessels, heart)• nutrient & waste transport• temperature control• pH balance
Lymphatic/Immune System(lymph & vessels, lymphocytes)
• fluid balance, transport• fat transport• immune responses
• movement of cells, hormones
(11 if you count the Integumentary System)
The Endocrine System(endocrine glands)• hormone production• physiological control
The Nervous System(brain, spinal cord, nerves)• internal, external sensation• behavioral control• physiological control
Organ Systems cont’d…
The Digestive System(esophagus, stomach, liver, intestines, pancreas)• food breakdown, absorption• waste disposal
The Urinary System(kidneys, bladder)• blood-borne waste disposal• salt & water homeostasis
The Respiratory System(pharynx, trachea, lungs)• gas exchange• pH balance
The Muscular System(all 3 muscle types)• movement of skeleton• movement in hollow organs• heartbeat
The Skeletal System(bones, cartilage, tendons…)• structural support• blood production• calcium, phosph. storage
The Reproductive System(ovaries, uterus, testes…)• gamete, production• hormone production• nurturing offspring
Key Terms for Chapter 20
Relevant Review Questions: 2-14
• connective tissue – loose, fibrous, specialized
• homeostasis
• epithelium – squamous, cuboidal, columnarsimple & stratified
• skeletal, smooth & cardiac muscle
• neurons & glial cells
Chapters 21-23, 25:Organ Systems of the Body
1. Circulatory System
2. Respiratory System
3. Digestive System
4. Urinary System
1. The Circulatory System
Organs of the Circulatory System
Roles of the Circulatory System
pumps the bloodHeart
Blood vessels
Blood
• deliver O2, remove CO2
• transport nutrients, wastes, hormones
• regulate temperature & pH
• immune protection (antibodies, white blood cells)
veins, arteries, capillaries
red & white blood cells, blood plasma
(we’ll also look at lymph and lymphatic vessels)
Vertebrate CirculationFish have a 2 chambered heart Reptiles &
amphibianshave a 3 chamberedheart
Mammals &birds have a heart with 4 chambers
rightatrium
leftatrium
semilunarvalve
semilunarvalve
atrioventricular(AV) valve
atrioventricular(AV) valve
rightventricle
leftventricle
The Human
Heart
The Cardiac Cycle
oxygenated vs deoxygenated
1 2 3
1. Atria contract, forcing blood from right atrium & left atrium into ventricles
2. Ventricles contract, forcing blood into aorta(fr. LV) and pulmonary artery (fr. RV)
3. Atria & ventricles relax (diastole), cycle repeats…
systole
1
2 7
8
9
2
3
4
5
6
4 10
3
9
8
superiorvena cava
capillaries ofhead, chest, and arms
pulmonaryartery
capillariesof left lung
pulmonary vein
aorta
left atriumleft ventricle
aorta
capillaries ofabdominal region
and legs
inferiorvena cava
right ventricle
right atrium
pulmonary vein
capillariesof right lung
pulmonaryartery
Blood Circulation
1 2 3 4
Pacemaker(SA node) AV node
Specializedmuscle fibers
Apex
Rightventricle
ECG
Control of the HeartbeatThe synchronous contraction of cardiac muscle cells is controlled by the sinoatrial (SA) & atrioventricular (AV) nodes.
• ea beat starts at the SA node, stimulates AV node (delayed)
Oxygen TransportOxygen is transported by redblood cells (RBCs)
• vast majority of blood cells (~99%) are RBCs
• aka erythrocytes
• each hemoglobinmolecule binds 8 O2
• vast majority of proteinin RBCs is hemoglobin
Oxygen binds to hemoglobin
• don’t have a nucleus!
in RBCs
Other Blood CellsBlood also contains:
• essential for blood clotting
• collective term for allcells of immune system
• B cells, T cells, monocytes, neutrophils…
Platelets
• “pinch off” from cells inbone marrow calledmegakaryocytes
White Blood Cells
Blood VasculatureArteries, arterioles:
• conduct blood flow awayfrom the heart
• usually oxygenated blood
Veins, venules:• conduct blood flow toward
the heart• usu. deoxygenated blood
Capillaries:• smallest vessels• where “exchange” occurs
CapillariesUnlike larger vessels, capillary walls are only 1 cellthick, barely wide enough for RBCs to pass through
• allows diffusion of gases,nutrients, wastes betweenblood & tissues
• some fluid (plasma)“leaks out” as well
The Lymphatic SystemA vascular system distinct from the circulatory system • conducts fluid “leaked” from
the blood called lymph
• lymph is filtered throughstructures called lymph nodes
• full of immune cells, important part of the immune response
• also transports fats fromdigestion in small intestine
• returned to blood at vena cava
Lymphatic Vessels
Fluid leaked fromcapillaries is takenup by “lymphcapillaries”
• lymph is conducted intolarger lymphatic vessels
• lymph passes throughlymph nodes before being“dumped” into the blood at the vena cava
2. The Respiratory System
The Respiratory System
• facilitate O2 uptake, waste CO2 removal
Respiratory System function :
Respiratory System OrgansNasal Cavity
Pharynx
Larynx
warms & moistens air
passage for air, food/water
vocal chords; where air, food separate
Epiglottis blocks airway when swallowing
Trachea connects airway to lungs
Lungs site of gas exchange
Diaphragm muscle used for “inhaling”
Rib cageexpands asrib musclescontract
airinhaled
Rib cage getssmaller asrib musclesrelax
airexhaled
lung
diaphragm
Diaphragm relaxes(moves up)
Diaphragm contracts(moves down)
Inhalation Exhalation
Inhalation & Exhalation
The LungsThe bronchi of the lungs branch into smaller andsmaller bronchioles which terminate in alveoli.
• alveoli are thesites of gasexchange
• arrangementmaximizes thesurface area forgas exchange
Gas Exchange in the AlveoliO2 and CO2 simply diffuse from higher to lowerconcentration across the capillary, alveolar epithelia
• O2 is moreconcentrated in the lungs than inthe blood
• CO2 is moreconcentrated in the blood than inthe lungs
*situation reversed in body tissues*
Summary of Gas Exchange
lungs
tissues
Deoxygenated blood from tissues returns to the right atrium &ventricle of the heart which pumps it to the lungs.
In the alveoli of the lungs bloodis oxygenated and flows backto the left atrium & ventricleof the heart, from which it is pumped back to the body.
3. The Digestive System
Digestive System Functions1) Digest food and absorb nutrients
• mechanical breakdown
2) Waste removal
• physical breakdown of food into smaller particles
• chemical digestion• breakdown of large molecules (polymers) into
smaller ones (monomers)
• absorption• transfer of digested material into blood & lymph
• undigested material & waste from liver
Organs of the Digestive System
• mouthDigestive Tract
• pharynx
• esophagus
• stomach
• small intestine
• large intestine
Accessory Organs • liver
• gall bladder
• pancreas
Bolus offood
Muscles relax,allowing passagewayto open
Stomach
Musclescontract,constrictingpassagewayand pushingbolus down
Muscles contract
Muscles relax
Muscles contract
Musclesrelax
Early DigestionMouth & Pharynx • chewing (mastication) of food,
mixing with saliva• swallowing of food bolus
Esophagus • muscular tube conducting foodbolus from pharynx to stomach
Stomach • mechanically “churns” food• adds pepsin (digests protein) and HCl (kills microbes, activates pepsin)
• starch digestion via amylase
Completion of DigestionSmall Intestine
• 3 sections: duodenum > jejunum > ileum
Pancreas • secretes “pancreatic juice”(enzymes, bicarbonate)to complete digestion
Liver & Gall Bladder • bile from liver added toduodenum via gall bladder
• bile helps emulsify fatsfor better digestion
• digestion is completed in the duodenum• absorption of nutrients
musclelayers
largecircular folds
villinutrient
absorption
Veinwith blooden route to
the liver
lumen
Lumen of Intestinenutrient
absorption
epithelialcells
bloodcapillaries
lymphvessel
Villi
nutrient absorption into epithelial cells
microvilli
Epithelial Cells
aminoacids and
sugars
fattyacids andglycerol
blood
fats
lymph
Intestinal Wall
Nutrient AbsorptionNutrients are absorbed throughout small intestine.
• nutrients are transferred to the blood or the lymph (fats)
Folds, Villi & Microvilli
Folds in the intestinal wall as well as villi & microvilligreatly increase surface area for nutrient absorption.
• villi are multicellular finger-like projections
• microvilli are projections on individual cells
Waste RemovalLarge Intestine: cecum > colon > rectum
• absorption of water, minerals, vitamins
• compaction, elimination of waste (undigested material, fiber, bacteria)
• houses a variety of beneficial bacteria (aka “probiotics”)
***bacteria need to be kept OUT of small intestine***
Largeintestine(colon)
Sphincter
Endof smallintestine
AppendixCecum
Anus
Rectum
Smallintestine
Nutrientflow
4. The Urinary System
The Urinary System
• removal of waste,excess in blood
• conduct urine fromkidneys to bladder
• holds, expels urine
• conducts urinefrom bladder “out”
Kidneys
Ureters
Bladder
Urethra
The KidneyOrganized into functional unitscalled nephrons
Nephron Structureglomerulus
Filtration in the Kidney1. Dissolved substances leave the blood in the
glomerulus, enter glomerular capsule > tubule
glomerulus
tubule
2. Needed H20, salt, nutrients reabsorbed from tubule
*maintains pH,salt & water
homeostasis*
3. Additional wastes added to urine
1 2
3
4. H2O reclaimed
4
Water & Salt HomeostasisAntidiuretic Hormone (ADH) regulateswater resorption in the kidneys:
• released by the pituitary gland• “sensors” in brain and heart regulate ADH release
• increases permeability of kidney tubules,greater water resorption
Aldosterone released from the adrenalcortex regulates “salt” levels:
• stimulates retention of sodium ions (Na+), excretion of potassium (K+) in kidneys
Key Terms for Chapters 21-23 & 25
• hemoglobin, white blood cells, platelets
• atrium, ventricle, aorta, vena cava
• sinoatrial, atrioventricular nodes
• arteries, arterioles, veins, venules, capillaries• lymph, lymph nodes
• pharynx, larynx, epiglottis, diaphragm, alveoli• villi, microvilli, • nephron, glomerulus, tubule
Relevant Review Questions: Ch. 21: 1 Ch. 22: 1, 2, 5, 7
Ch. 23: 1, 2, 4, 5 Ch. 25: 2, 4