1. There are two mechanisms for the human immune systems.
What are they called?
What is the major difference between the two mechanisms?
(1) Specific Defense Mechanism: Target on specific pathogens.
(2) Non-specific Defense Mechanism: Target on all pathogens.
2. What are the types the non-specific defense mechanisms?
(1) Physical barrier
(2) Chemical barrier
(3) blood clotting
(4) phagocytosis
(5) inflammatory response
3. What is the purpose of physical barrier?
Prevent the entry of pathogen into the human body.
4. What are the structures involved in physical barrier?
(1) Skin
(2) inner wall along the respiratory track
5. How can the skin for a physical barrier to prevent the entry of pathogen?
(1) The skin cover the whole body.
(2) The outermost layer of the skin is composed of dead cells. It is basically water-proof and is effective in preventing the growth of pathogen.
(3) The dead cells are constantly sloughed off. So the pathogens that are attached to them.
6. How can the inner wall of the respiratory track form a physical barrier to prevent the entry of pathogen?
- There are mucus secreting cells and ciliated epithelial cells.
- Mucus secreting cells secrete mucus which traps/stick the pathogens.
- The cilia of the ciliated epithelial cells beats to sweep the mucus towards the pharynx,
- The mucus is then swallowed or coughed out.
7. What does chemical barrier consist of?
(1) Tear: lysozyme is present in the tear.
(2) Saliva: lysozyme is present in the saliva.
(3) Sebum: It is antiseptic.
(4) Gastric juice: Contains Hydrochloric acid(corrosive, kill pathogens).
(5) Vaginal secretion: contains weak acid(kills pathogens).
8. What is the importance of blood clotting?
To close up the wound and prevent further entry of pathogens.
9. What are the materials required for blood clotting?
(1) fibrinogen
(2) blood platelets
(3) red blood cells
(4) white blood cells
10. What is the mechanism of phagocytosis?
- Pathogen enters the human body,
- Phagocytes(a type of white blood cell) moves towards the pathogens,
- then it engulf the pathogen by phagocytosis so that the pathogen is inside the cell.
- After that enzymes are released to digest the pathogen.
11. What is the process of inflammatory response?
(1) The body tissue is damaged/ruptured,
(2) Damaged tissue release chemicals
(3) such that the arterioles around the wound dilate, causing more blood to flow near the wound, making wounded area red.
(4) the permeability of the blood capillary increases, more phagocytes and plasma leave the blood capillary, the wounded area becomes swollen which cause an increase in pressure. Pressure causes pain.
12. What does the pus in the inflamed area consists of?
(1) dead pathogens
(2) dead or living phagocytes.
13. What is specific defense mechanism?
- involves immune response.
- lymphocytes are responsible for carry out the process.
14. What are the two types of lymphocytes.
(1) B cells (produced and mature in the bone marrow, B has the meaning of BONE)
(2) T cells (produced in the bone marrow, but mature in the thymus gland.)
15. What is antigen?
They are molecules that can combine with specific receptors on the surface of B cells or T cells.
They will usually stimulate the body to produce immune response.
16. What are the two types of antigen?
(1) Self-antigen (the unique molecules on the surface of the cells of human body cells).
- In normal situation, will not inflict immune response.
(2) foreign antigen (from outside)
- will inflict immune response.
17. What kinds of molecules can be antigens?
(1) The proteins / glycoproteins from the surface of foreign cells
(2) The proteins on the surface of virus / bacteria.
(3) toxins secreted by bacteria
(4) Snake venom
(5) hair
(6) other substances (e.g. pollen)
18. How does the immune response carried out by B cells works?
(1) B cells combines with the antigen(on the surface of pathogens) and become activated,
(2) activated B cells divides actively into many same copies,
(3) some of these cells differentiate into plasma cells, some differentiate into memory B cells.
(4) the plasma cells produce antibodies which are specific to an antigen so that one specific pathogen can be dealt with.
(5) memory B cells can identify the antigen such that in case they come into contact with similar antigen again, the immune response will be fast.
19. What are antibodies?
- Y shape protein molecules.
- They combines with antigen to form an Antigen-Antibody Complex.
20. How does antibodies fight pathogens or toxins?
(1) Activate certain protein and cause the pathogens to lyse, called ‘Lysis’.
(2) Stick together into a clump, called ‘clumping’, which facilitate phagocytosis.
(3) neutralize toxins.
21. How does the immune response carried out by T cells works?
(1) Helper T cells and antigen (antigen of the pathogen) combines, and be activated.
(2) Helper T cells
- secretes lymphokines activates phagocytes,
- cause other T cells to divide and become
1. killer T cells: which kills infected cells
2. memory T cells: which can identify the antigen so that in case they come into contact with similar antigen again, the immune response will be fast.
(3) activate B cells, such that B cells will divide and differentiate into plasma cells and memory B cells.
22. Which kind of lymphocyte are responsible for producing antibodies?
The plasma cells that are differentiated from B cells.
23. What is the differences between primary immune response and secondary immune response?
Secondary response are
(1) faster in response, which means faster in starting to produce antibodies.
(2) faster in producing antibodies.
(3) producing greater number of antibodies.
(4) the concentration of antibodies last longer before reducing to original level.
24. What it the principle of vaccination?
- Inject the vaccine into the blood.
- stimulate the body to produce a primary immune response,
- such that corresponding memory cells can be made,
- when in next time, the same antigen arrive, a faster response can be made.
25. Vaccine must contain antigens, so what can vaccine consists of?
(1) alive but attenuated pathogens,
(2) dead pathogens,
(3) toxins from bacteria that has been deactivated.
(4) the antigen protein itself. (e.g. protein coat of virus, cloned antigen)
26. What is the meaning of active immunity?
The type of immunity that is obtained by the body itself producing antibodies.
27. Examples of natural active immunity and artificial active immunity:
Natural active immunity: obtained from the person himself/herself getting infected and later recovered / got cured.
Artificial active immunity: obtained from vaccination.
28. What is passive immunity?
Antibodies come from external source.
29. What are the examples of natural passive immunity and artificial passive immunity?
Natural passive immunity: Antibodies are transferred from the mother to the foetus during pregnancy; Antibodies are transferred to the baby while breast feeding.
Active passive immunity: Direct injection of antibodies.