1. The Circulatory System

2. Parts of the circulatory system
Blood, blood vessels and heart

3. Describe the structure and function of the heart.
There are four major blood vessels associated with the heart:
Pulmonary Veins: This transports oxygenated blood from the lungs to the left atrium
Aorta: This transports oxygenated blood from the heart to the rest of the body and the brain.
Vena Cava: This transports deoxygenated blood from the rest of the body to the heart.
Pulmonary Artery: Transports deoxygenated blood to the heart to the lungs.

4. What is the job of the septum?
 It keeps deoxygenated blood separate from oxygenated blood

5. What is the job of the valves, how do they do this?
Valves prevent the blood from flowing backwards. It opens to allow blood to flow through and then closes to prevent backflow.

6. Describe the relative thickness of the muscle wall of the left and right ventricles. Explain the reason for the difference.
The right ventricle walls are thinner as it only needs to pump blood to the lungs.
The left ventricle has to pump blood to the whole body. It has to work harder and so has the thick, muscular walls.

7. Describe the contraction of muscles of the atria and ventricles.
Heart beats as the cardiac muscles in its walls contract and relax;
When they contract, heart becomes smaller, squeezing blood out. This is called systole;
When they relax, the heart becomes larger, allowing blood to flow into the atria and ventricles. This is called diastole;
The rate at which heart beats is controlled by a patch of muscle in the right atrium called pacemaker;
The pacemaker sends electrical signals through the walls of the heart, which make the muscle contract

8. Organ To
From
Heart
Vena cava and pulmonary vein
Pulmonary artery and aorta
Lungs
Pulmonary artery
Pulmonary vein
Liver
Hepatic portal vein & hepatic artery
Hepatic vein
Kidney
Renal artery
Renal vein

9. Types of Blood Vessel
Artery: blood vessel that carries blood away from the heart
Vein: blood vessel which returns blood towards the heart
Capillary: blood vessel that connects arteries to veins and allows exchange of material between blood and cells of the body

10. Arteries Arteries have thick muscular walls. Why?
They carry blood at high pressure

11. Veins Pumps blood at low pressure Wider space inside than arteries
Carry de-oxygenated blood
Why do veins have valves?
To prevent backflow of blood

12. Capillaries Microscopic and highly branched vessels
Why are the walls only one cell thick?
To allow efficient diffusion of substances such as glucose, water, oxygen and carbon dioxide

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14. Blood
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15. What are the components of the blood?
• Red blood cells (Erythrocytes)  – haemoglobin and oxygen transport. • White blood cells (Leucocytes) – phagocytosis and antibody formation, • Platelets (Thrombocytes) – causing clotting
• Plasma – transport of blood cells, ions, soluble nutrients, hormones and carbon dioxide.
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16. Red Blood Cells (Erythrocytes)
Red in colour
Produced in red bone marrow
Life span about 120 days  destroyed in spleen
Biconcave Disk Shape
No nucleus
Contain haemoglobin

17. Carrying oxygen

18. White Blood Cells (Leucocytes)
Bigger than Red Blood Cells
Exist in fewer amounts than Red Blood Cells
Have a nucleus

19. White Blood Cells (Leucocytes)
Variety of types
Function – fight infection
lymphocytes – antibody production
phagocytes – phagocytosis

20. Platelets (Thrombocytes)
Very small fragments of cells
No nucleus
Irregular shape
Sticky outer membrane
Help clot blood

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25. Blood clotting A blood clot consists of: A plug of platelets
A network of insoluble fibrin molecules
Fibrinogen gets converted into fibrin to for a mesh

26. Glossary Atrium– the first chamber into which blood enters.
Ventricle – the lower chambers of the heart. Blood is pumped from these.
Arteries – Blood vessels that take blood away from the heart.
Veins – Blood vessels that bring blood back to the heart.
Capillaries – the smallest blood vessels. Where Oxygen and nutrients leave the blood
Coronary arteries – arteries that supply blood to the heart
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27. Glossary Haemoglobin – oxygen-carrying protein in red blood cells
Lymph – a transparent liquid found within the lymphatic vessels, and collected from tissues in all parts of the body and return to the blood via the lymphatic system
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