C16L2
Chapter 16
Lesson 2

Functions of the Circulatory System
•
Your circulatory system is important for transporting materials from one part of your body to another
•
As blood travels through the circulatory system, it picks up carbon dioxide produced during cellular respiration and wastes produced by all the other chemical reactions that take place inside cells.

the three main components of the circulatory system
•
Blood vessels
•
Heart
•
Blood

The Heart and Blood Vessels
•
The human heart pumps an average of 8,000 gallons of blood through 12,000 miles of blood vessels every 24 hours.
•
cardio - refers to the heart
•
vascular - refers to blood vessels

•
Cardiovascular disease is the leading cause of death in the U.S.
•
Heart disease alone accounts for over 1/3 of all deaths in the U.S. Each year more than
700,000 people die of heart attacks
(myocardial infarction) in the U.S. (Almost
2,000 Americans die of heart disease each day. That is one death every 44 seconds.)

•
Diet
•
Exercise
•
Stress

Closed Circulatory System the blood remains in vessels

Three types of blood vessels
•
ARTERIES
•
VEINS
•
CAPILLARIES

which carry blood away from the heart; thick muscle layers permit the arteries to constrict, controlling blood pressure

carry blood toward the heart;have little to do with blood pressure; thinner and less muscular walls; they have 1-way valves allow blood to go toward the heart but not away from it

approximately
50,000 miles of capillaries in an adult tiny vessels connecting arteries and the veins; velocity is slowest here - red blood cells go through single file

Arteries branch into smaller vessels called arterioles.
Capillaries join and form larger vessels called venules, and venules join and form veins.

The Structure of the Heart

heart size about the size of your fist approximately
5 inches long,
3.5 inches wide, and
2.5 inches thick

heart weight man's heart weighs about 11 ounces woman's heart weighs about 9 ounces

section of tissue inside heart that causes it to beat automatically at your normal resting rate

the heart beats at an average rate of 72 times per minute

Parts of the Heart

PERICARDIUM thin sac completely enclosing the heart; made of tough tissue; protects heart from rubbing against the lungs and the wall of the chest; has a smooth lining that secretes a slippery liquid

muscular wall dividing the heart lengthwise

CHAMBERS
1
3
2
4
(four of them
- two on each side); also called cavities

R
ATRIUM (Auricle)
2 upper chambers
L collects the blood flowing into the heart

The heart is a muscle that pushes blood through the circulatory system.
•
The heart is a muscle that pushes blood
Blood enters the upper two chambers of the heart, called the atria .
•
Blood leaves through the lower two chambers of the heart, called the ventricles .

R
Right ATRIUM collects deoxygenated blood from the body

Left ATRIUM
L collects oxygenated blood from the lungs

VENTRICLES
2 lower chambers
R
L pumps the blood into the arteries

Right VENTRICLE pumps only to lungs
R

Left VENTRICLE
L pumps to the entire body
(wall 3 times as thick as the right side)

Lesson 2

Lesson 2

HEART VALVES
(four of them
- controls the flow of blood through the heart

ATRIOVENTRICULAR VALVES
T
M
(AV valves) between an atrium and a ventricle

TRICUSPID VALVE between the right atrium and right ventricle

MITRAL VALVE (bicuspid) between the left atrium and left ventricle

SEMILUNAR VALVES
P
A control the flow of blood from ventricle to arteries

PULMONARY VALVE between the right ventricle and the pulmonary artery

AORTIC VALVE between the left ventricle and the aorta

Tricuspid Valve

Tricuspid Valve

CORONARY ARTERIES carry oxygen to heart muscle
(nourishes the heart)

The largest veins in the human body:
• SUPERIOR VENA CAVA returns blood from the upper body regions
• INFERIOR VENA CAVA returns blood from the lower body regions

The largest artery in the human body:

Types of Circulation
Systemic circulation is the network of vessels that carry blood from the heart to the body and from the body back to the heart.
A network of arteries and veins called the coronary circulation supplies blood to all the cells of the heart.

Types of Circulation
(cont.)
• The network of vessels that carries blood to and from the lungs is called pulmonary circulation .
•
Pulmonary circulation carries oxygen-poor blood from the heart to the lungs and oxygen-rich blood from the lungs back to the heart.

Lesson 2

The Circulatory System and
Homeostasis
•
Once oxygen enters your body, the respiratory system interacts with the circulatory system and transports oxygen to your body’s cells.
•
It also transports nutrients from the digestive system and hormones from the endocrine system.
•
The nervous system regulates your heartbeat.

Some
Disorders
& Diseases of the
Circulatory
System

a condition in which there is a decrease in hemoglobin or in the number of erythrocytes

a permanent stretching of an artery, caused by the pressure of blood on muscular walls weakened by disease or injury

an irregularity of the heartbeat

The buildup of fatty material within the walls of arteries that can interfere with blood flow is called atherosclerosis .

results from broken blood capillaries in the skin and underlying tissue. The diffusion and breaking down of blood causes the
"black and blue" marks.

A heart attack happens when part of the heart muscle dies or is damaged.
A heart attack is usually caused when not enough oxygen reaches cells in the heart.

Most heart attacks occur when a coronary vessel is blocked.

Heart failure occurs when the heart is not working efficiently.

a break in a blood vessel resulting in loss of blood it may be due to physical injury or disease

Blood pressure higher than
140/90 mm Hg is known as hypertension, or high blood pressure.

a disease characterized by an increase in the number of leukocytes. It is usually fatal but in some cases has been brought under control.

a sudden loss of consciousness caused by a hemorrhage or a blood clot in arteries in or around the brain

Most strokes occur when a vessel in the brain is blocked.

veins that are distended, swollen, and knotted. They are more common in people who stand for long period of time.

Circulatory System Health
Most circulatory system disorder risk factors can be controlled by eating a healthy diet, controlling weight, exercising, and not smoking.