Chapter 8: Transport In Humans

Question 1

Explain how the process of platelets work

Answer 1

1. Damaged capillaries, tissue, and platelets produce thrombokinase
2. Thrombokinase converts prothrombin into thrombin
3. Thrombin converts soluble fibrinogen into insoluble fibrin threads to form a mesh to trap blood cells. It forms a wound to prevent the entry of micoorganisms

Question 2

Explain phagocytosis

Answer 2

Phagocytosis is carried out by phagocytes.
Phagocytosis is the process of engulfing a foreign particle such as bacteria or microorganisms by white blood cells

Question 3

Explain antibody production

Answer 3

Antibody production is caused by lymphocytes.
They neutralise the toxins produced by bacteria and causes them to agglutinate so that they can be easily ingested by phagocytes

Question 4

Explain tissue rejection

Answer 4

A diseased or damaged organ can be replaced with a new organ by an organ doner.

However, the organ recipient´s immune system may treat the organ as an foreign body. This induces antibody production and cause a tissue rejection

Question 5

State the characteristics of artery

Answer 5

Function: Carries blood away from the heart
Thickness of wall: It has thick muscular walls to withstand high pressure
Lumen: Small lumen
Valves: Absent

Question 6

State the characteristics of veins

Answer 6

Function: Carries blood towards the heart
Thickness of wall: It has thin muscular, elastic walls as blood is flowing through low pressure
Lumen: Largest lumen
Valves: Present (to prevent backflow of blood)

Question 7

State the characteristics of capillaries

Answer 7

Function: Allow the exchange of substances between blood and tissue by diffusion
Thickness of wall: Only one-cell thick (to allow permeability to water and other dissolved substances)
Lumen: Smallest lumen
Valves: Absent

Question 8

State the function of coronary heat disease

Answer 8

• Coronary heart disease is the occlusion of the coronary artery caused by the fat deposits in the inner walls of the artery
• This reduces flow of blood to heart muscles
• This reduces supply of nutrients, glucose, and oxygen which is required for aerobic respiration to provide energy to keep the heart contracting
• This will cause the heart muscles to stop contracting, hence leading to a heart attack

Question 9

State the possible causes of CHD and how to prevent it

Answer 9

1. Emotional stress. Prevent it with proper stress management by relaxing through hobbies
2. Smoking. Avoid smoking as cigarette smokes contains nicotine and carbon monoxide which leads to increased CHD

Question 10

Explain the cardiac cycle

Answer 10

1. Muscles of atria and ventricles relax.
2. Muscles of atria contract, forcing blood into ventricles. AV valves open. Semi-lunar valves closed
3. Muscles of ventricles contract, muscles of atria relax (to receive blood from veins). AV valves closed, Semi-lunar valves open
4. Muscles of ventricles relax.
   - Blood from the right ventricles is pumped into the pulmonary artery in the lungs
   - Blood from the left ventricles is pumped into the aorta to the rest f the body

Question 11

Explain why two sides of the heart is completely divided by the median septum

Answer 11

• To prevent the mixing of deoxygenated blood from the right side of the heart with oxygenated with left side of the heart
• This reduces the amount of oxygen carried to the tissue cells

Question 12

Explain why the atria have thinner muscular walls

Answer 12

• Atria only pumps blood to the ventricles which does not require high pressure
• However, the ventricles pumps blood out of the heart which requires high pressure. Thus, thicker.

Question 13

Explain why the left ventricle has thicker muscular walls than right ventricles

Answer 13

• Left ventricles pumps blood into the aorta to the rest of the body which requires high pressure
• Right ventricle pumps blood into the pulmonary artery into the lungs which does not require high pressure