1. The Circulation System
Chapter 6

2. The Circulation System
The circulation system consists of blood, arteries, veins, capillaries and the heart.

3. Blood
Description
Function
Plasma
A pale yellow liquid
To transport food, hormones, blood cells, oxygen, carbon dioxide, salts and urea; used to regulate body temperature
Red Blood Cells
Circular shaped with no nucleus, they are made in the bone marrow.
To carry oxygen to the cells for respiration.
White Blood Cells
They are larger than red blood cells. They can change shape and are also made in the bone marrow.
To fight infection
Platelets
Small fragments of cells made in bone marrow
To Clot blood

4. Types of Blood Cell

5. Functions of the Blood Transport: Defence against disease:
The main function of the blood is to transport substances around the body.
Defence against disease:
Some white blood cells eat up (engluf) bacteria and pathogens.
Other white blood cells make antibodies that kill bacteria and pathogens

6. The Blood Vessels There are 3 types of blood vessels Arteries Veins
Capillaries

7. Arteries Arteries carry blood away from the heart.
Blood is under high pressure in the arteries.
Thick muscle walls to withstand high pressure.
Arteries have a narrow lumen or space.
Arteries have no valves.
Arteries carry oxygenated blood

8. Arteries

9. Veins Veins carry slow moving blood back to the heart.
Veins have thinner walls and a large lumen.
Veins have valves to prevent the backflow of blood.
Veins carry de-oxygenated blood.

10. Vein

11. Capillary Capillaries are tiny microscopic blood vessels
Capillary walls are only one cell thick.
Substances pass into and out of the blood through the capillaries.

12. Capillary

13. Veins, Arteries and Capillaries

14. The Heart

15. The Heart
De-oxygenated blood enters the right atrium through a vein called the vena cava.
This blood is pumped to the right ventricle and then to the lungs through the pulmonary artery.
The blood gets oxygen in the lungs and enters the left atrium through the pulmonary vein.
Blood is pumped to the left ventricle which pumps the blood through the aorta all around the body.

17. Pulse
When we feel our pulse this is the blood flowing through our arteries.
When we exercise:
Our muscles need more oxygen and energy.
Our heart beats faster to pump more blood to the muscles.
Hence our pulse rate increases.
Pulse is measured in BPM (beats per minute)

18. Body Temperature
Our body needs to maintain an internal temperature of about 37oC.
When we get sick the activity of the white blood cells may cause this temperature to rise, this is called a fever.