1. Higher Human Biology Subtopic 13 Circulatory system
Physiology and Health
Higher Human Biology
Subtopic 13
Circulatory system

2. Learning Intentions To discuss the need for the cardiovascular system
To state the different types of blood vessel and describe features of each.
To explain what tissue fluid is
To explain the function of the lymphatic system

3. Reminder
What can you remember about the heart?

4. The Circulatory System
Made up of :
the heart, blood vessels and blood
Important because :
Substances need to be exchanged
- the external environment and
the organism
- the cells and structures in the organism

5. Lungs Body cells the right side of the system
deals with deoxygenated blood.
the left side of the system
deals with oxygenated blood.

6. Some key functions :
Transport oxygen
Remove carbon dioxide and wastes
Transports nutrients
Fight disease
Transport hormone

7. Carotid artery
Jugular vein
Pulmonary vein
Pulmonary artery
aorta
Vena cava
Hepatic artery
Hepatic portal vein
Gut artery
Renal vein
Renal artery

8. Blood Vessels Vessels have a lumen – central cavity
It is lined with epithelial cells
There are 3 types of blood vessel….
- Artery
- Vein
- Capillary

10. The ARTERY
Arteries carry blood AWAY from the heart under high pressure.
The elastic fibres allow the artery to stretch and recoil under pressure
Narrow lumen
The thick muscle can contract to push the blood along.

12. Vasoconstrition and Vasodilation
The smooth muscle of the arterioles :
- contracts (vasoconstriction) to reduce blood flow
- relax (vasodilation) to increase blood flow

13. The CAPILLARY Capillaries link arterioles to venules.
They exchange materials between the blood and other body cells
The wall of a capillary
is only one cell thick to allow…..
……rapid exchange

15. Veins carry blood TOWARDS the heart under low pressure.
The VEIN
Veins carry blood TOWARDS the heart under low pressure.
Veins have valves which act to stop the blood from going in the wrong direction.
thin muscle and elastic fibres
Wide lumen

17. Capillaries Arteriole Capillaries (capillary bed) Venule video
Capillaries do not have such a complex structure as their role is to allow exchange of materials via diffusion. They have a capillary wall which is made up of one layer of epithelium cells and a lumen.
video 17 17

18. Tissue Fluid and the Lymphatic System

19. Blood consists of rbc, wbc and platelets bathed in plasma.
Plasma contains e.g :
carbon dioxide
glucose
amino acids
proteins
ions

20. The CAPILLARY BED (tissue fluid)
The squeezed out liquid is tissue fluid.
It has little/no protein.
Blood arrives at the capillaries under high pressure and is forced through.
body cell
Blood undergoes pressure filtration and plasma is squeezed out.

21. Exchange
Tissue fluid has a HIGHER concentration of useful molecules e.g. oxygen than the cell…..
……these diffuse in
The cells have a HIGHER concentration of waste e.g. carbon dioxide than the fluid…
…..this diffuses out

22. Most of the tissue fluid returns to the blood at the venule side.
Osmotic Return
body cell
Tissue fluid
Most of the tissue fluid returns to the blood at the venule side.
Some doesn’t return and enters lymphatic vessels and is now called lymph. 22

23. Lymph passes into lymphatic system
Blood arriving in the arteriole high pressure
Lymph vessel
Blood leaving in venule
low pressure
Some tissue fluid enters capillary by osmosis
capillary
Some tissue fluid enters lymphatic system
Some plasma forced out of capillary
Tissue fluid

24. Lymph
Lymph is moved through vessels due to the muscular contraction during breathing, locomotion and movement.
They contain valves to prevent backflow.
Lymph vessels eventually return their contents to the main circulation near the heart via osmosis.

25. Kwashiorkor and Elephantiasis

26. Learning Intentions To discuss the need for the cardiovascular system
To state the different types of blood vessel and describe features of each.
To explain what tissue fluid is
To explain the function of the lymphatic system