INTERNATIONAL UNIVERSITY

The circulatory system and the heart

Dr Sam Nang

Generality• Your heart and circulatory system make

up your cardiovascular system. • Your heart works as a pump that pushes

blood to the organs, tissues, and cells of your body.

Generality• Blood delivers oxygen and nutrients

to every cell and removes the carbon dioxide and waste products made by those cells.

• Blood is carried from your heart to the rest of your body through a complex network of arteries, arterioles, and capillaries.

Generality• Blood is returned to your heart

through venules and veins.• If all the vessels of this network

in your body were laid end-to-end, they would extend for about 60,000 miles (more than 96,500 kilometers), which is far enough to circle the earth more than twice!

Generality• The one-way circulatory system

carries blood to all parts of your body.

• This process of blood flow within your body is called circulation.

Generality

• Arteries carry oxygen-rich blood away from your heart, and

• veins carry oxygen-poor blood back to your heart.

Generality• In pulmonary circulation:• the pulmonary artery that brings

oxygen-poor blood into your lungs and

• the pulmonary vein that brings oxygen-rich blood back to your heart.

Generality In the diagram :• the vessels that carry oxygen-

rich blood are colored red, and • the vessels that carry oxygen-

poor blood are colored blue.

Generality• Twenty major arteries make a path

through your tissues, where they branch into smaller vessels called arterioles.

• Arterioles further branch into capillaries, the true deliverers of oxygen and nutrients to your cells.

Generality• Most capillaries are thinner than

a hair.• In fact, many are so tiny, only

one blood cell can move through them at a time.

Generality• Once the capillaries deliver oxygen

and nutrients and pick up carbon dioxide and other waste, they move the blood back through wider vessels called venules.

• Venules eventually join to form veins, which deliver the blood back to your heart to pick up oxygen.

INTERNATIONAL UNIVERSITY

The Heart

Dr. Sam Nang

The Heart

• The heart weighs between 7 and 15 ounces (200 to 425 grams) and is a little larger than the size of your fist.

• By the end of a long life, a person's heart may have beat (expanded and contracted) more than 3.5 billion times.

The Heart

• In fact, each day, the average heart beats 100,000 times, pumping about 2,000 gallons (7,571 liters) of blood.

The Heart• Your heart is located between

your lungs in the middle of your chest, behind and slightly to the left of your breastbone (sternum).

• A double-layered membrane called the pericardium surrounds your heart like a sac.

The Heart

• The outer layer of the pericardium surrounds the roots of your heart's major blood vessels and is attached by ligaments to your spinal column, diaphragm, and other parts of your body.

The Heart

• The inner layer of the pericardium is attached to the heart muscle.

• A coating of fluid separates the two layers of membrane, letting the heart move as it beats, yet still be attached to your body.

The Heart

• Your heart has 4 chambers. • The upper chambers are called

the left and right atria, and• The lower chambers are called

the left and right ventricles.

The Heart

• A wall of muscle called the septum separates the left and right atria and the left and right ventricles.

• The left ventricle is the largest and strongest chamber in your heart.

The Heart

• The left ventricle's chamber walls are only about a half-inch thick, but they have enough force to push blood through the aortic valve and into your body.

The Heart (Valves)

• Four types of valves regulate blood flow through your heart:

• The tricuspid valve regulates blood flow between the right atrium and right ventricle.  

The Heart (Valves)

• The pulmonary valve controls blood flow from the right ventricle into the pulmonary arteries, which carry blood to your lungs to pick up oxygen.

• The mitral valve lets oxygen-rich blood from your lungs pass from the left atrium into the left ventricle.  

 

The Heart (Valves)

• The aortic valve opens the way for oxygen-rich blood to pass from the left ventricle into the aorta, your body's largest artery, where it is delivered to the rest of your body.

THE END