Circulation

Chapter 12

THE BODY’S TRANSPORTATION SYSTEMSection 1

Movement of Materials

The cardiovascular system- circulatory system that consists of the heart, blood vessels, and blood

The cardiovascular system carries needed substances to cells such as oxygen and glucose to produce energy

It carries waste products away from cells such as carbon dioxide

It transports white blood cells that attack disease-causing mico-organisms

Structure and Function of the HeartThe Heart’s Structure How the Heart Works

In the first phase the heart muscle relaxes as the atria fills with blood

In the second phase, the atria contracts and fills the ventricles ; ventricles then contract to pump blood forward

The heart has two sides- a right and left- separated by a wall of tissue

It has two upper chambers- atrium that receive blood that comes into the heart

Ventricles- two lower chambers that pump blood out of the heart

Valves- flap of tissue that prevents blood from flowing backward located between each ventricle and the blood vessels that carry blood away

Regulation of Heartbeat

Pacemaker- group of cells located in the right atrium, sends out signals that make the heart muscle contract

The pacemaker responds to the body’s oxygen needs by adjusting the heart rate

Pacemakers can become damaged, and an artificial one implanted

The Heart

Arteries- blood vessels that carry blood away from the heart

Capillaries- tiny vessels into which blood flows and substances are exchanged between the blood and body cells and back to the veins

Veins- Vessels that carry blood back to the heart

Two LoopsLoop One: to the Lungs and Back

Loop Two: to the Body and Back

In the second loop, blood is pumped from the heart throughout the body and then returns again to the heart

The left atrium fills with oxygenated blood from the lungs and that then moves to the left ventricle

Blood then flows into the aorta- the largest artery in the body

From the aorta, oxygen rich blood flows to the body and then back to the right atrium

In the first loop, blood travels from the heart to the lungs and then back to the heart

Blood flows from the body into the right atrium and contains little oxygen

Blood then flows to the right ventricle out to the lungs

From the lungs oxygen rich blood returns to the left side of the heart

The Force of the Ventricles The ventricles of the heart

exert a force on the blood inside them

The force moves blood out of your heart and into your arteries

The contraction of the left ventricle exerts a much stronger force than that of the right ventricle because it must move blood throughout the body while the right ventricle moves blood only to the lungs

Review What is the function of the cardiovascular system?

What function does the heart perform?

Describe the route that blood takes through the cardiovascular system. Begin with blood leaving the left ventricle.

What is the heart’s pacemaker? To what internal stimulus does the pacemaker respond?