CHAPTER 37 CIRCULATORY AND

RESPIRATORY SYSTEMS

The Circulatory System 37-1 Key Questions:

• What are the structures of the circulatory system?

• What are the 3 types of blood vessels in the circulatory system?

What are the structures of the circulatory system? The human circulatory system consists of the heart, a series of blood vessels, and the blood that flows through them.

Why do we need a circulatory system?

• Organisms composed of a small number of cells don’t need a circulatory system. Most cells in such organisms are in direct contact with the environment. Oxygen, nutrients, and waste products can easily diffuse back and forth across cell membranes

• Larger organisms, however, cannot rely on diffusion. Most of their cells are not in direct contact with the environment, and substances made in one part of the organism may be needed in another part.

Heart• As you can feel with your hand, your heart is located near the

center of your chest• The heart, which is composed almost entirely of muscle, is a hollow

organ that is about the size of your clenched fist• The heart is enclosed in a protective sac of tissue called the

pericardium • In the walls of the heart, there are two thin layers of epithelial and

connective tissue that form a sandwich around a thick layer of muscle called the MYOCARDIUM. The powerful contractions of the myocardium pump blood through the circulatory system

• There is a right side and a left side to the heart – they are separated by the septum (wall) which prevents the mixture of oxygen-rich and oxygen-poor blood

• Atrium (atria is plural) – two of these upper chambers; receives the blood

• Ventricle – two of these lower chambers; pump blood out of heart

What is pulmonary circulation?

•Occurs on the right side of the heart

•Blood is pumped from the heart to the lungs and back to the heart again

Why would your blood get pumped to the lungs and then back to the heart?•Oxygen poor blood goes to the lungs to get rid of carbon dioxide and pick up oxygen•The oxygen rich blood then has to go back to the heart to get pumped to the rest of the body

What is systemic circulation?

• Occurs on the left side of the heart• Oxygen rich blood from the lungs

gets pumped throughout the rest of the body and back to the heart – now the blood is oxygen poor and must go to the lungs to dump the carbon dioxide

FYI: ALL BLOOD IS RED!!!

What makes your heart “beat’?    -There are two networks of muscle fibers in the heart, one in the atria and one in the ventricles

   -When a single fiber in either network is stimulated, all the fibers are stimulated and the network contracts as a unit

  -Each contraction begins in a small group of cardiac muscle cells located in the right atrium—the sinoatrial node

  -Because these cells “set the pace” for the heart as a

whole, they are also called the pacemaker -Although the heartbeat is not directly controlled by the nervous system, the autonomic nervous system does influence heart rate.

-Neurotransmitters released by neurons from one part of the nervous system can increase heart rate. Those released by neurons in a different part of the nervous system can decrease heart rate

What determines if your heart beats

fast or slow? Your heart can beat faster or more slowly, depending on your body’s need for oxygen-rich blood.

In times of stress, does the heart beat faster or slower?

It beats faster

What are the three types of blood

vessels? ARTERIES•Large vessels that carry blood from the heart to the tissues of the body

•All arteries carry oxygen rich blood except for the pulmonary artery

•Aorta is the largest artery leaving the heart

•Walls contain connective tissue, smooth muscle and epithelial cells

CAPILLARIES

• Smallest blood vessels• Walls are only one cell thick• Most are so narrow that blood cells

must pass through single file• Bring nutrients and oxygen to the

tissues and absorb carbon dioxide and other waste products

VEINS• Once blood has passed through the

capillary system, it must be returned to the heart.

• Walls contain connective tissue, smooth muscle and epithelial tissue

• The largest veins contain one-way valves that keep blood flowing toward the heart

• Many veins are located near skeletal muscles. When these muscles contract, they help to force blood through the veins.

• Blood flow through the veins of the arms and legs often occurs against the force of gravity.

• Exercise helps to keep blood from accumulating in the limbs and stretching the veins out of shape

Blood Pressure

•When the heart contracts, it produces a wave of fluid pressure in the arteries.

•The force of the blood on the arteries’ walls is known as blood pressure.

•Blood pressure decreases when the heart relaxes, but the system still remains under pressure.

• Sphygmomanometer – device that measures blood pressure– A cuff is wrapped around the upper arm. Air

is pumped into the cuff until blood flow through an artery is blocked.

– As the pressure is released, the worker listens to the pulse and records two numbers from a pressure gauge.

– The first number is the systolic pressure—the force felt in the arteries when the ventricles contract.

– The second number is the diastolic pressure—the force of the blood felt in the arteries when the ventricles relax. An average adult’s blood pressure is 120/80.

Disorders of the circulatory

system

ATHEROSCLEROSIS - fatty deposits called plaque build up on the walls of arteries

•If these deposits get too large, they obstruct the flow of blood and may cause an increase in blood pressure

•The plaque buildup also increases the risk of blood clots. If a clot breaks free, it can get stuck in an artery and obstruct blood flow to tissues beyond the clot

High Blood Pressure• If blood pressure is too high, medical

problems may result• High blood pressure, or hypertension,

forces the heart to work harder, which may weaken or damage the heart muscle and blood vessels.

• People with high blood pressure are more likely to develop heart disease and to suffer from other diseases of the circulatory system.

• Hypertension increases the risk of heart attack and stroke.

Heart Attack • Atherosclerosis is particularly dangerous in the

coronary arteries, the set of small arteries that bring oxygen and nutrients to the heart muscle itself. If one of these arteries becomes blocked, part of the heart muscle may begin to die from lack of oxygen—a condition known as a heart attack.

• The symptoms of a heart attack include nausea, shortness of breath, and severe, crushing chest pain. People who show these symptoms need immediate medical attention.

• New drugs are available that can increase blood flow enough to save heart cells. These drugs must be given in the early stages of a heart attack to save the heart muscle and prevent cell death.

Stroke

• Blood clots formed as a result of atherosclerosis may break free and get stuck in one of the blood vessels leading to a part of the brain.

• Brain cells served by that blood vessel gradually die from a lack of oxygen, and brain function in that region may be lost.

• A stroke can also occur when a weakened artery in the brain bursts, flooding the area with blood.

• Depending on what part of the brain they affect, strokes may cause paralysis, loss of the ability to speak, and even death.

Prevention of Circulatory System Disorders 

• Like most other disorders, cardiovascular disorders are easier to prevent than to cure.

• Exercise, weight control, sensible diet, and not smoking seem to be the keys to avoiding cardiovascular disorders.

• Exercise increases your respiratory system’s efficiency. It helps control your weight, reduces body fat, and reduces stress. It also strengthens your muscles, including your heart.

• A diet low in saturated fat can reduce your risk of developing heart disease.

37-2 Blood and the Lymphatic System

• Key Questions:– What is the function of each

type of blood cell?– What is the role of the

lymphatic system?

What is “blood” made up of?

           -Plasma

         -Red blood cells

        -White blood cells

         -Platelets

-Clotting proteins

PLASMA•Straw colored fluid in blood; about 55% of the blood,90% water,10% other stuff (dissolved gases, salts, nutrients, enzymes, hormones, waste products, and proteins called plasma proteins)•Plasma proteins, albumin, globulin, and fibrinogen, perform a variety of functions•Albumins and globulins transport substances such as fatty acids, hormones, and vitamins.•Albumins also help to regulate osmotic pressure and blood volume.•Some globulins fight viral and bacterial infections.•Fibrinogen is the protein responsible for the ability of blood to clot.

RED BLOOD CELLS• Aka: erythrocytes – transport oxygen

They get their color from HEMOGLOBIN – iron-containing protein that binds to oxygen in the lungs and transports it throughout the body where oxygen gets released

• Shaped like discs• Made in the bone marrow• Mature red blood cells do not have nuclei• Live for 120 days and then destroyed on

liver and spleen

WHITE BLOOD CELLSAka: leukocytes – attack foreign substances or

organisms

Produced in red bone marrow

Some live for months others only a few days

PHAGOCYTES – “eating cells” – engulf and digest foreign cells

Some slip across capillary walls and attack invading organismsOthers release chemicals that help the body fight disease

Platelets and blood clotting

We don’t want to lose our blood How does bleeding stop?

-We have the ability to form clotsBlood clotting is made possible by plasma proteins and cell fragments called PLATELETS - Cell fragments released by bone marrow

When platelets come into contact with a wound they become sticky and other platelets start to stickThey release proteins called clotting factors that cause other types of proteins to form a mesh over the wound – this is called a clot

Lymphatic systemAs blood circulates, some fluid leaks from the blood into the surrounding tissues.A network of vessels called the lymphatic system collects the fluid that is lost by the blood and returns it to the circulatory system. LYMPH – the fluidLymph nodes – act as filters by trapping bacteria

Lymph vessels

37-3 The Respiratory System

• Key Questions:–What are the structures of the respiratory system?

–How does smoking affect the respiratory system?

Structures of the respiratory system

PHARYNX – passageway for both air and food

TRACHEA – air moves through here; aka: windpipe

LARYNX – contains two highly elastic folds of tissue called vocal cords; when air passes the folds vibrate to produce sound

DIAPHRAGM – flat muscle at bottom of chest cavity that helps with breathing

BRONCHI – after the trachea there are these two passageways; they lead to the lungsBRONCHIOLES – smaller branches after the bronchiALVEOLI – tiny air sacs where gas exchange occurs- Surrounding the alveoli are capillaries where the respiratory and circulatory systems meetDIAPHRAGM – flat muscle at bottom of chest cavity that helps with breathing

How is breathing controlled?

Combination of voluntary and involuntary

-You can hold your breath for only so long and your involuntary muscles kick in and force you to breathe

-Cells in the medulla oblongata measure how much carbon dioxide there is in the blood

Trace the path of an oxygen molecule through the human

body

Tobacco and the Respiratory System

• The upper part of the respiratory system is generally able to filter out dust and foreign particles that could damage the lungs. Millions of people engage in an activity—smoking tobacco—that damages and eventually destroys this protective system.

• Tobacco smoke contains many substances that affect the body.

• Three of the most dangerous substances are nicotine, carbon monoxide, and tar. – Nicotine is a stimulant drug that increases the heart

rate and blood pressure. – Carbon monoxide is a poisonous gas that blocks the

transport of oxygen by hemoglobin in the blood. It decreases the blood’s ability to supply oxygen to its tissues, depriving the heart and other organs of the oxygen they need to function.

– Tar contains a number of compounds that have been shown to cause cancer.

• Smoking can cause such respiratory diseases as chronic bronchitis, emphysema, and lung cancer.

• Smoking is also a major cause of heart disease. Smoking constricts, or narrows, the blood vessels. This causes blood pressure to rise and makes the heart work harder.

• Whatever the age of a smoker, and no matter how long that person has smoked, his or her health can be improved by quitting. Nicotine is a powerful drug with strong addictive qualities that make it very difficult to quit smoking. Thus, considering the cost, the medical dangers, and the powerful addiction, the best solution is not to begin smoking.

How are these two body systems related? Why are they so important?

The respiratory system brings oxygen into the body and expels carbon dioxide from the body. The circulatory system transports these gases throughout the body