(i)

Differences between a vein and an artery

(ii)

Functions of red blood cells

1. They carry oxygen from lungs to cells
2. They carry carbon dioxide from the cells to lungs

(iii)

Diseases associated with the circulatory system

1. High blood pressure (Hypertension)
2. Low blood pressure (Hypotension)
3. Varicose veins
4. Piles/Haemorrhages
5. Anaemia
6. Leukaemia/blood cancer
7. Arteriosclerosis
8. AIDS
9. Hepatitis
10. Heart failure/Cardiac arrest
11. Sickle cell anaemia
12. Diabetes
13. Stroke
14. Haemophilia
15. Coronary artery disease/Thrombosis
16. Malaria

i)

Components of blood

1. Red blood cells/haemoglobin
2. White blood cells/phagocytes/lymphocytes
3. Hormones
4. Water
5. Oxygen
6. Carbon dioxide
7. Salts
8. Glucose
9. Amino acids/proteins
10. Urea
11. Vitamins
12. Plasma

ii)

Functions of blood

1. It carries hormones
2. It carries oxygen
3. It carres food to all parts of the body
4. It removes waste products of cell activities (metabolism)
5. It fights against disease causing organisms
6. It prevents entry of germs into the body through a wound
7. It forms clots which prevents excessive bleeding
8. It regulates body temperature

(α)

Red blood cells

Carry oxygen towards the tissues from the lungs/carbon dioxide

(β)

White blood cells

Protects against illness/fights parasites

(γ)

Blood plasma

Maintains blood pressure and circulation/transport nutrients/heat/water/hormones, etc.

i)

Functions of blood

1. Transport
2. Protection/defence
3. Regulation of temperature
4. Aids erection
5. Regulates the pH

ii)

Function of blood vessels

Channels which transport/conduct blood to all parts of the body.

iii)

Function of the heart

Pumps/distributes blood to all parts of the body.