The Circulatory SystemThe Circulatory System

A & P - Mr. Carlson

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Major Structures of the Circulatory System

• Heart

• Blood Vessels

• Blood

• Lymph Nodes

• Lymph

• Lymph Vessels

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The Heart• The heart is the central

organ of the cardiovascular system.

• Beats more than 2.5 billion times in an average lifespan.

• Lies within the thoracic cavity, behind the sternum, and between the lungs.

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Heart Parts• The pericardium is a tough

sac-like membrane that surrounds the heart and functions to secrete a fluid that reduces friction as the heart beats.

• The septum vertically divides the heart into two sides.

• Right side pumps blood to lungs.

• Left side pumps blood to other parts of the body.

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Heart Chambers• The heart is divided

into upper & lower chambers.

• Each upper chamber is called an atrium.

• Each lower chamber is called a ventricle.

• There are four total chambers.

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Heart Valves• Atrioventricular valves

separate each atrium from each ventricle.

• AV valves consist of flaps of tissue that open in only one direction.

• The AV valve on the right is called the tricuspid valve.

• The AV valve in the left is called the mitral valve.

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Heart Valves• Semilunar valves separates

the ventricles from large blood vessels on each side of the heart.

• SL valves are also one-way valves.

• The SL valve on the right is known as the pulmonary valve.

• The SL valve on the left is known as the aortic valve.

Patterns of Circulation

• The heart and blood vessels from one continuous, closed system of circulation.

• This system also consists of two primary subsystems:

• Pulmonary Circulation – Blood travels between heart and lungs.

• Systemic Circulation – Blood travels between the heart and all other body tissues.

Circulation of Blood in the Heart

• Deoxygenated blood from the body returns via the superior & inferior vena cava to the right atrium.

• The right atrium pumps blood through the tricuspid valve to the right ventricle.

• The muscles of the right ventricle contract and force the blood into the pulmonary arteries, which lead to the lungs.

• In the lungs, carbon dioxide diffuses out and oxygen diffuses into the blood.

Circulation of Blood in the Heart

• Oxygenated blood from the lungs returns via the Pulmonary Veins to the left atrium.

• From the left atrium, blood passes through the mitral valve into the left ventricle.

• Contraction of the muscular walls of the left ventricle force the blood into a large blood vessel called the aorta.

• From the aorta, blood is distributed to the rest of the body except the lungs.

Whew!!!Have you had enough yet?

I didn’t even include the SL Valves in the last description!

Almost there!

Control of the Heartbeat

• The heart consists of muscle cells that contract in waves. When the first group of muscle cells is stimulated it sets off a chain reaction that travels across the heart.

• The sinoatrial (SA) node is a group of specialized heart-muscle cells located in the right atrium that is stimulated first.

• The SA node is called the pacemaker because it regulates the rate of contraction of the entire heart.

• The atrioventricular (AV) node is located in the septum between the atria and relays the electrical impulse to the muscle cells that are located in the ventricles.

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Heart Disease

• The end result of untreated heart disease is a heart attack.

• Heart disease is one of the leading causes of death in the United States.

• Elevated cholesterol levels is a major factor in creating heart disease.

• The CDC estimates the number of americans that are overweight or obese is currently at 61%.