1. Circulatory System

2. Why do we need a transport system?
We have a small surface area to volume ratio
Simple diffusion throughout the body surfaces is insufficient
Useful substances needs to transported through the body and unwanted substances needs to be eliminated

3. What is the importance of the circulatory system?
It transports blood throughout our body – to all parts of our body
Needed substances by the body such as: oxygen, nutrients and hormones are sent to all cells in the body
Unwanted substances such as carbon dioxide and nitrogenous waste products are sent to be eliminated by the body.

4. What does our transport system consist of?
A transporting medium – the blood
Tubes through which the medium can travel – blood vessels
A pump to push the medium through the tubes – the heart

5. Objective: To describe the composition and components of blood

7. what’s in BLOOD digested food red blood cells white blood cells oxygen
waste (urea)
platelets
carbon dioxide
hormones
plasma

8. The Blood
white blood cell
red blood cell
plasma
platelets

9. Blood Components

10. Composition of Blood
Blood is composed of three types of cells: red blood cells, white blood cells and platelets, floating in a liquid called plasma.
Plasma makes up 55% of the volume of the blood and the cells make up the other 45%

11. Blood Cells

12. Blood = 55% Plasma + 45% Blood Cells

13. Red Blood Cells
contain haemoglobin, a molecule specially designed to hold oxygen and carry it to cells that need it.
a biconcave disc that is round and flat without a nucleus
can change shape to an amazing extent, without breaking, as it squeezes single file through the capillaries.

14. Red Blood Cells (Erythrocytes)
Formation – red bone marrow of the pelvis, scapula, ribs, sternum etc
Destroyed in the liver and spleen
Functions – transport oxygen as oxyhaemoglobin from lungs to tissues. Transport small amounts of carbon dioxide from tissues to lungs

15. How do red blood cells transport oxygen?
In their cytoplasm is a red pigment called haemoglobin
Haemoglobin has a high affinity for oxygen
It forms an unstable compound called oxy-haemoglobin
In conditions of low oxygen concentration oxy-haemoglobin breaks down and releases the oxygen.

16. Oxygen in Red Blood Cells

17. Did you know?
There are about 5 ½ million red blood cells in a cubic millimetre of blood
A red blood cells lasts for about 4 months
About 200 billion red blood cells are formed and destroyed each day
About 1% of the total red blood cells are replaced each day.

18. White Blood Cells (Leucocytes)
there are many different types and all contain a big nucleus.
the two main ones are the phagocytes and the lymphocytes.
phagocytes ‘eat’ or engulf disease causing bacteria in the blood at sites of infection and the lymph nodes
some lymphocytes fight disease by making antibodies to destroy antigens (foreign proteins) by dissolving them.
other lymphocytes make antitoxins to break down poisons.

19. Platelets (Thrombocytes)
Platelets are formed in the bone marrow of long bones by disintegration of certain cells .
Platelets produce tiny fibrinogen fibres to form a net. This net traps other blood cells to form a blood clot.

20. Plasma It also contains useful things like; carbon dioxide glucose
amino acids
proteins
minerals
vitamins
hormones
waste materials
like urea.
A straw-coloured liquid that carries the cells and the platelets which help blood clot.

21. Objective: To describe the structure and function of blood vessels

22. blood from the heart gets around the body through blood vessels
There are 3 types of blood vessels
a. ARTERY
b VEIN
c CAPILLARY

24. Arteries carry blood away from the heart.
The ARTERY
Arteries carry blood away from the heart.
the elastic fibres allow the artery to stretch under pressure
thick muscle and elastic fibres
the thick muscle can contract to push the blood along.

25. Arteries Carries high pressure oxygenated blood away from the heart
Blood moves in pulses created by ventricle contractions
Most lie deep in the body where they are protected
Thick elastic walls composed of three layers to withstand high pressures of blood
Arteries divide into smaller vessels called arterioles

26. Structure of an artery

27. The CAPILLARY Capillaries link Arteries with Veins
they exchange materials between the blood and other body cells.
the wall of a capillary
is only one cell thick
(endothelial cells)
The exchange of materials between the blood and the body can only occur through capillaries.

28. The CAPILLARY A collection of capillaries is known as a capillary bed.
arteriole
venule
capillaries
body cell

29. Did you know?
The capillary network is so dense that no living cell is far from a supply of food and oxygen
In the liver every cell is in direct contact with a capillary. Why do you think this is so?
Some capillaries are so narrow that the red blood cells are squeezed flat while passing through them.

30. Veins carry blood towards from the heart.
The VEIN
Veins carry blood towards from the heart.
veins have valves which act to stop the blood from going in the wrong direction.
thin muscle and elastic fibres
body muscles surround the veins so that when they contract to move the body, they also squeeze the veins and push the blood along the vessel.

31. Structure of Veins

32. Vein Valves

35. Varicose Veins This happens when the valves stop working properly
The blood is left in the veins instead of flowing back to the heart
This makes the vein swell and causes a varicose vein
Varicose veins show up on the legs ankle and knees because they are furthest from the heart

38. SUMMARY copy and complete the following;
Arteries take blood ______ from the heart. The walls of an artery are made up of thick _________ walls and elastic fibres. Veins carry blood ________ the heart and also have valves. The _________ link arteries and veins, and have a one cell thick wall. Blood is made up of four main things ______, the liquid part of the blood; Red Blood Cells to carry ______; White Blood cells to protect the body from disease and _________ to help blood clot.
away
muscular
towards
capillaries
plasma
oxygen
platelets