Outline The Physiological Processes Of Immunity In The Context Of Activities And Passive Immunity

Question 1

Explain acquired immunity - the first response

Answer 1

The immune response to an antigen following the first exposure is called the primary response.

There is a slow and delayed rise in antibody levels, peaking 1-2 weeks after infection.
The antibody produced is mainly IgM ( M for main sign of invasion).
This delayed response reflects the time required to activate the T cell system, which then Stimulates B cell division.

Antibody levels start to fall once the infection is cleared, but if the immune system has responded well, it will have generated a population of long lived memory B cells, making the individual immune to future infection.

Question 2

Explain acquired immunity - the secondary response

Answer 2

Second and subsequent exposure gives rise to a secondary response ( getting ill with the same illness again ).

The immune response is much faster and 10-15 times more powerful because the memory B cells generated after the first infection rapidly divide and antibody production begins almost immediately. Antibody produced is mainly ImG ( G for granny, last a long time and is very large), which is more effective than IgM.

Question 3

Explain acquired immunity - active / passive, natural / artificial

Answer 3

Active: the individual has responded to an antigen and produced their own antibodies, lymphocytes are activated and the memory cells formed provide long-lasting resistance.

Passive: the individual is given antibodies produced by someone else. The antibodies break down with time so passive immunity is relatively brief.

Natural : the body may be stimulated to produce its own antibodies by either having the disease or having a sub clinical infection (active). Acquired before birth by the passage of material antibodies across the placenta to the foetus, and to the baby in breast milk (passive).

Artificial : in response to the administration of dead or live artificially weakened pathogens (vaccines) or deactivated toxins (toxoids) (active). Ready made (vaccine) antibodies, in human or animal serum, are infected into the recipient (passive).

Question 4

Describe Anti D immunoglobulin

Answer 4

• if mother is rhesus negative ( Rh-) and foetus is rhesus positive (Rh+), the mother will mount an immune response to the rehash’s antigens on the fetal blood cells. The mothers immune system recognises them as foreign bodies.

These antibodies made by the mother can pass through the placenta and destroy the feta, red blood cells in the fetal circulation, as well as in her own circulation.

This can cause fetal anemia, fetal hydrous, haemolytic disease of the new born and neonatal jaundice.

Administering Anti-D immunoglobulin mops up the circulation fetal red blood cells, preventing the mother from making excessive antibodies.

Summary:
Mum blood mixes with baby THEN mum makes immune response to foreign RH+ antigen THEN those antibodies go into placenta and destroy baby RBC.