Circulatory System

I. Overview

A. Functions of the Circulatory System (CS)

1. Internal transport system

2. Delivers O2 and nutrients to cells

3. Removes CO2 and metabolic wastes from cells

4. Interacts with digestive, endocrine, respiratory and excretory systems to maintain homeostasis

Circulatory System

B. Two Types of circulatory systems1. Open CS

a. Found in smaller and simpler organisms (e.g. arthropods and mollusks) b. Blood is pumped into open spaces called sinuses.

2. Closed CSa. Found in larger and more complex organisms

(e.g. earthworms and vertebrates) b. Blood stays in vessels and is pumped in a loop under pressure.

• The human circulatory system is comprised of three components: the heart, blood vessels and blood

Circulatory System

II. The HeartA. Function

1. Pump blood throughout the bodyB. Structure

• Surrounded by a thin protective sac called the pericardium

• Majority of the heart is muscle called the myocardium• Right and left side are divided by the septum• Upper chambers, which receive blood are the atria• Lower chambers, which pump blood to the body are the

ventricles• Flaps of connective tissue called valves are located

between the atria and ventricles

Circulatory SystemC. Blood flow through the heart and body

1. Blood returns from the upper and lower body through the superior and inferior vena cavas

2. The vena cavas empty into the right atrium

Superior Vena Cava

Inferior Vena Cava

Right Atrium

Circulatory System

3. The blood now passes through the tricuspid valve into the right ventricle.

Tricuspid Valve

Right Ventricle

Why do we have valves?

Circulatory System

4. Next blood is pumped past the pulmonary semilunar valve into the pulmonary artery.

Pulmonary Semilunar

Valve

Pulmonary Artery

Circulatory System

5. Blood is pumped from the left and right branches of the pulmonary artery to the left and right lobes of the lungs.

In the lungs, what happens to the blood?Carbon dioxide is released from the blood stream and oxygen is absorbed.

Capillaries of head and arms

Capillaries of abdominal organs and legs

Inferior vena cava

Pulmonary veinCapillaries of

right lung

Superior vena cava

Aorta Pulmonary artery

Capillaries of left lung

Circulatory System

6. Blood returns from the lungs to the heart via the pulmonary veinspulmonary veins.7. The pulmonary veins empty into the left atrium.

Pulmonary Veins

Pulmonary Veins

Left Atrium

Circulatory System

8. Blood is pumped through the bicuspid (mitral) valve into the left ventricle.

Bicuspid (mitral) Valve

Left Ventricle

Circulatory System

9. Blood is pumped from the left ventricle through the aortic semilunar valve into the Aorta.

Aortic Semilunar

Valve

Aorta

DRAW FIG. 37-3, PG. 945

Right VentricleRight Ventricle

Right AtriumRight Atrium

Left AtriumLeft Atrium

Inferior Vena CavaInferior Vena CavaVein that brings oxygen-poor Vein that brings oxygen-poor blood from the lower part of blood from the lower part of the body to the right atriumthe body to the right atrium

Tricuspid ValveTricuspid ValvePrevents blood from flowing Prevents blood from flowing

back into the right atrium after it back into the right atrium after it has entered the right ventriclehas entered the right ventricle

Pulmonary ValvePulmonary ValvePrevents blood from flowing Prevents blood from flowing back into the right ventricle back into the right ventricle

after it has entered the after it has entered the pulmonary arterypulmonary artery

Pulmonary VeinsPulmonary VeinsBring oxygen-rich blood from Bring oxygen-rich blood from

each of the lungs to the left atriumeach of the lungs to the left atrium

Superior Vena CavaSuperior Vena CavaLarge vein that brings oxygen-poor blood Large vein that brings oxygen-poor blood

from the upper part of the body to the right from the upper part of the body to the right atriumatrium

AortaAortaBrings oxygen-rich blood from the left Brings oxygen-rich blood from the left

ventricle to the rest of the bodyventricle to the rest of the body

Pulmonary ArteriesPulmonary ArteriesBring oxygen-poor blood Bring oxygen-poor blood

to the lungsto the lungs

Aortic ValveAortic ValvePrevents blood from flowing Prevents blood from flowing back into the left ventricle back into the left ventricle

after it has entered the aortaafter it has entered the aorta

Mitral ValveMitral ValvePrevents blood from flowing back Prevents blood from flowing back

into the left atrium after it has into the left atrium after it has entered the left ventricleentered the left ventricle

Left VentricleLeft Ventricle

SeptumSeptum

http://www.pbs.org/wgbh/nova/heart/heartmap.html

DRAW FIG 37-2, pg. 944Capillaries of Capillaries of

head and armshead and arms

Capillaries of Capillaries of abdominal abdominal

organs and legsorgans and legs

Inferior Inferior vena cavavena cava

Pulmonary Pulmonary veinveinCapillaries Capillaries

of right lungof right lung

Superior Superior vena cavavena cava

AortaAorta Pulmonary Pulmonary arteryartery

Capillaries Capillaries of left lungof left lung

Circulatory System

D. Heart Rate1. Controlled by contractions of a small group of

muscle cells located in the right atrium called the pacemaker

Circulatory System

2. Factors that affect HRa. Blood Pressure - increase in BP will cause an

increase in HR

b. Carbon dioxide – increase in CO2 in blood will cause an increase in HR

c. Gender - females have higher HR than malesd. Age - the older you get the lower your HR e. Temperature - as body temperature increases

so does HRf. Drugs – stimulants and depressants

Circulatory System

III. Blood Vessels (3 Main Types)A. Arteries

1. Thick walled and muscular Why2. Carry blood AWAY from the heart to tissues

and organs Do arteries always carry oxygenated blood?Artery VeinCapillary

Circulatory System

B. Capillaries

1. Walls are very thin and porous; one-cell thick and very narrow Why?

2. Exchange of materials Which materials?

Artery Vein

Capillary

Circulatory SystemC. Veins

1. Thin-walled and less muscular2. Carries blood TOWARDS the heart3. Many are located near and between skeletal

muscles (WHY?)4. Large veins contain valves (WHY?)

What happens if we sit or stand too long? Do veins always carry deoxygenated blood?

Artery VeinCapillary

Circulatory System

Circulatory System

D. Types of Blood Cells (3 Types)1. Red Blood Cells (Erythrocytes):

a. Transport oxygen using special iron-containing protein called hemoglobin that binds oxygen

b. Disk-shapedc. Produced from cells in red

bone marrowd. Have no nucleus and die

after ~100 days

Circulatory System

2.2. WhiteWhite Blood Cells (Leukocytes)a. Protect the body against infectionb. Use phagocytosis to engulf pathogens

Circulatory System

3. Platelets (Thrombocytes)a. Stimulate the formation of blood clots b. Platelets come into contact with a damaged blood

vesselc. Platelets rupture releasing clotting factorsd. Platelet factors react with factors in the plasma

forming a clote. This process occurs within minutes

V. Disorders of the blood

A. Anemia1. Reduction in bloods ability to carry oxygen2. Causes by lack of iron, reduce RBC formation, excessive

bleeding or it can be genetic (Thalassemia)

B. Leukemia

1. Inability to fight off infection

2. Caused by an uncontrollable production of immature leukocytes (cancer of the blood)

C. Hemophila and Sickle-Cell Anemia

Circulatory System

VI. Disorders of the Blood VesselsA. Varicose Veins

1. Cause - valves in the veins fail and blood over-stretches the veins

2. Prevention – exercise, don’t cross legs over knees.

** Hemorrhoids are varicose veins in the rectum.

B. Aneurysm1. Artery wall is weakened; bulges

2. Hereditary

3. Symptoms - none!

Circulatory System

VII. Cardiovascular Disease

B. Most common form is Coronary Heart Disease 1. Cause

a. Slow build up of fatty plaque (atherosclerosis) along the walls of the coronary arteries

b. Reduced blood flow to heart leads to a heart attack2. Symptoms of a heart attack

a. Pain in chest and left arm, cyanosis of lips, dizziness, shortness of breath, denial!

A. Kills over 1 million Americans a year!

C. Stroke (The interruption of blood flow to the brain)1. Causes

a. Blood clot

b. Atherosclerosis

c. An aneurysm

D. Risk Factors associated with Heart Disease (Check your parents!)

1. age2. gender3. genetics4. diets high in fat (hyperlipidemia)5. high blood pressure6. smoking7. stress8. alcohol9. obesity10. inactivity

CS Summary Movie