The Circulatory System. Chapter 17 Lesson 1

(1)

The Circulatory System

Chapter 17 Lesson 1 Chapter 17 Lesson 1

(2)

Functions of the Circulatory System

• •

Your circulatory system maintains an internal Your circulatory system maintains an internal

environment in which all the cells in your body are environment in which all the cells in your body are

nourished.

• •

As your heart pumps blood, blood vessels carry oxygen As your heart pumps blood, blood vessels carry oxygen and nutrients to the body cells.

and nutrients to the body cells.

• •

At the same time, carbon dioxide and waste matter are At the same time, carbon dioxide and waste matter are carried from your cells and delivered to your lungs and carried from your cells and delivered to your lungs and

kidneys for removal from the body.

(3)

Structure of the Circulatory System

• • The main parts of your circulatory system are The main parts of your circulatory system are

your heart, blood, arteries, veins, and capillaries

through which fluids are carried throughout your

body.

(4)

The Heart

• •

Along with your brain, your heart is the most important Along with your brain, your heart is the most important of your body

of your body’s vital organs. ’s vital organs.

• •

Your heart never rests, pumping blood continually to the Your heart never rests, pumping blood continually to the lungs and the rest of the body.

lungs and the rest of the body.

• •

Much of the heart consists of a special type of muscle Much of the heart consists of a special type of muscle called

called

myocardium myocardium

• •

The myocardium contracts rhythmically and The myocardium contracts rhythmically and automatically.

automatically.

(5)

Chambers of the Heart

• •

A thick muscular wall called the septum divides the A thick muscular wall called the septum divides the interior of the heart into right and left halves.

interior of the heart into right and left halves.

• •

Each half has two chambersEach half has two chambers--an upper chamber called an an upper chamber called an

atrium,

and a lower chamber called a and a lower chamber called a

ventricle. ventricle.

• •

OneOne--way valves at the exits of each chamber guarantee way valves at the exits of each chamber guarantee that blood can only flow in one direction.

that blood can only flow in one direction.

• •

The natural sound of the heart is related to the The natural sound of the heart is related to the movements of these muscles and valves.

movements of these muscles and valves.

(6)

Circulation of the Heart

•• Blood that has been depleted of oxygen but contains carbon dioxide Blood that has been depleted of oxygen but contains carbon dioxide and waste matter is carried to the heart by two large blood vess

and waste matter is carried to the heart by two large blood vessels els called the

called the vena cavavena cava..

•• This blood enters the right atrium, is transferred to the right This blood enters the right atrium, is transferred to the right ventricle, then is pumped to the lungs.

ventricle, then is pumped to the lungs.

•• Blood picks up oxygen from the lungs and releases carbon dioxide. Blood picks up oxygen from the lungs and releases carbon dioxide.

•• The newly oxygenated blood then enters the left atrium, is The newly oxygenated blood then enters the left atrium, is transferred to the left ventricle, and then pumped to all the ti

transferred to the left ventricle, and then pumped to all the tissues ssues of the body.

of the body.

Blood flow: vena cava

Blood flow: vena cava--right atriumright atrium--right ventricleright ventricle--lungslungs--left atriumleft atrium--left left ventricle

ventricle--aorta. aorta.

(7)

Blood

• •

Blood is the fluid that transports all of the substances Blood is the fluid that transports all of the substances that your body needs to sustain life.

that your body needs to sustain life.

• •

Blood delivers oxygen, hormones, and nutrients to cells Blood delivers oxygen, hormones, and nutrients to cells and carries away the wastes the cells produce.

and carries away the wastes the cells produce.

• •

55% of the total volume of blood is made up of 55% of the total volume of blood is made up of plasma

plasma--

the fluid in which other parts of the blood are the fluid in which other parts of the blood are

suspended.

Red Blood cells carry oxygen from the lungs to the body Red Blood cells carry oxygen from the lungs to the body’’s s

tissues, where oxygen is exchanged with carbon dioxide.

Each red blood cell contains

Each red blood cell contains hemoglobinhemoglobin--

the oxygen the oxygen

carrying part of blood.

(8)

Blood cont.

• •

White blood cells protect the body against infection and White blood cells protect the body against infection and fight infection when it occurs.

fight infection when it occurs.

• •

White blood cells are larger than red blood cells, but White blood cells are larger than red blood cells, but there are fewer of them.

there are fewer of them.

• •

Production of white blood cells increases when there is Production of white blood cells increases when there is an infection.

an infection.

• •

Some white blood cells surround invading pathogens and Some white blood cells surround invading pathogens and ingest them, while others form antibodies to make you ingest them, while others form antibodies to make you

immune to second attacks.

(9)

Blood cont.

• •

PlateletsPlatelets--

are the cells that prevent the body’ are the cells that prevent the body ’s loss of s loss of

blood.

• •

Platelets initiate a chain reaction that causes blood to Platelets initiate a chain reaction that causes blood to clot.

clot.

• •

When platelets come into contact with damaged blood When platelets come into contact with damaged blood vessel walls, they become sticky and clump the site of vessel walls, they become sticky and clump the site of

the injury.

• •

Platelets produce small fibers called Platelets produce small fibers called

fibrin. fibrin.

• •

Fibrin traps platelets along with red blood cells and white Fibrin traps platelets along with red blood cells and white blood cells to help blood clot.

blood cells to help blood clot.

(10)

Blood Vessels

•• There are more than 60,000 miles of blood vessels in your body. There are more than 60,000 miles of blood vessels in your body.

They are divided mainly into three types:

•• Arteries-Arteries- the vessels that carry blood away from the heart. the vessels that carry blood away from the heart.

Pulmonary arteries carry blood from the right ventricle of the h

Pulmonary arteries carry blood from the right ventricle of the heart eart to the lungs. Systemic arteries carry blood from the left ventr

to the lungs. Systemic arteries carry blood from the left ventricle of icle of the heart to the rest of the body.

the heart to the rest of the body.

•• Arteries have thick, muscular, flexible walls that enable it to Arteries have thick, muscular, flexible walls that enable it to withstand high blood pressure whenever the heart beats.

withstand high blood pressure whenever the heart beats.

•• Smaller vessels called Smaller vessels called arterioles arterioles branch directly off an artery and branch directly off an artery and connect to even smaller blood vessels called capillaries.

connect to even smaller blood vessels called capillaries.

(11)

Blood Vessels cont.

• •

CapillariesCapillaries--

are the vessels that carry blood between are the vessels that carry blood between

arterioles and small vessels called

arterioles and small vessels called venules venules . .

• •

Capillaries open and close in response to the bodyCapillaries open and close in response to the body’’s s need for oxygen and nutrients.

need for oxygen and nutrients.

• •

Some capillaries are 50 times thinner than a strand of Some capillaries are 50 times thinner than a strand of hair.

hair.

• •

The opening and closing of capillaries in the skin plays The opening and closing of capillaries in the skin plays an important role in regulating the body

an important role in regulating the body’’s temperature. s temperature.

(12)

Blood Vessels cont.

• •

VeinsVeins--

the vessels that return deoxygenated blood the vessels that return deoxygenated blood

toward the heart from the body

toward the heart from the body’ ’s organs and tissues. s organs and tissues.

• •

Like arteries, veins have a smooth, strong, flexible wall, Like arteries, veins have a smooth, strong, flexible wall, however the pressure in veins is much lower then that of however the pressure in veins is much lower then that of

arteries.

• •

The inner lining of veins form valves to help prevent The inner lining of veins form valves to help prevent blood from flowing back into the capillaries.

blood from flowing back into the capillaries.

(13)

The Lymphatic System

• •

The lymphatic system serves 2 functions. The lymphatic system serves 2 functions.

• •

1. Drains tissue back into the bloodstream.1. Drains tissue back into the bloodstream.

• •

2. Helps fight infection.2. Helps fight infection.

• •

The lymphatic system is your bodyThe lymphatic system is your body’s second circular ’s second circular

system since any fluid that is not absorbed through the system since any fluid that is not absorbed through the

walls of blood vessels is returned to the heart through it.

• •

Lymphatic fluid is circulated by movement of the body’Lymphatic fluid is circulated by movement of the body’s s muscles since it does not have a pump like the heart.

muscles since it does not have a pump like the heart.

(14)

Lymph

• •

The fluid that the lymphatic system transports is The fluid that the lymphatic system transports is lymph-lymph-

a clear yellow fluid that fills spaces around body cells.

• •

Lymph is made up of proteins, fats, and Lymph is made up of proteins, fats, and lymphocyteslymphocytes--

white blood cells that protect the body against

pathogens

pathogens- - disease carrying agents. disease carrying agents.

(15)

Types of Lymphocytes

• •

BB--cellscells-- 10% of lymphocytes are B-10% of lymphocytes are B-cells. cells.

• •

When BWhen B--cells encounter pathogens they are stimulated cells encounter pathogens they are stimulated to enlarge and multiply. B

to enlarge and multiply. B--cells turn into plasma cells, cells turn into plasma cells, and plasma cells produce antibodies to destroy invading and plasma cells produce antibodies to destroy invading

pathogens.

• •

TT--cellscells-- Two main groups: killer cells and helper cells. Two main groups: killer cells and helper cells.

• •

Killer TKiller T--cells attach to abnormal cells and release toxins cells attach to abnormal cells and release toxins to destroy them.

to destroy them.

• •

Helper T-Helper T-cells aid the activity of the Bcells aid the activity of the B--cells and killer T-cells and killer T- cells and control other aspects of the body

cells and control other aspects of the body’s immune ’s immune system.

system.

(16)

Structure of the Lymphatic System

• •

Lymphatic vessels are distributes throughout the body Lymphatic vessels are distributes throughout the body the same way blood vessels are.

the same way blood vessels are.

• •

At certain places along the lymphatic vessels, lymph At certain places along the lymphatic vessels, lymph passes through lymph nodes.

passes through lymph nodes.

• •

The nodes act as a barrier to the spread of infection, The nodes act as a barrier to the spread of infection, destroying or filtering out bacteria before they pass into destroying or filtering out bacteria before they pass into

the blood.