38 - Immune system (non-specific + specific immunity). Immune tolerance

Question 1

Immunity

Answer 1

A complex physiological process whose functions is to store the constancy of internal environment of the body by protecting it from all foreign endogenous + exogenous factors

Question 2

Innate immunity

Answer 2

Prevents entry of MOs into tissues

If they enter it eliminated them before the occurrence of disease

• Present from birth + is non-specific
• Doesn’t become more efficient on subsequent exposure to same organism

Question 3

Non-specific immunity

Answer 3

Provides general protection ⇢ responds to inflammation

1st line of defence:

• Mechanical barrier⇢ skin + mucosa
• Chemical barrier⇢ Saliva, Enzymes + Secretory immunity

2nd line of defence:

• Phagocytosis⇢ Neutrophils, macrophages + histiocytes
• Natural killer cells ⇢ kill tumour + infected cells

Question 4

Non-specific protective factors

Answer 4

Tissue factors ⇢ skin + mucosa

Cellular factors ⇢ neoplastic cells, synthesised cells of specific immunity

Hormonal factors ⇢ mediators

Question 5

Specific immunity

Answer 5

Response after primary inflammation

Aka acquired immunity

• Occurs in response to infections ⇢ adaptive immunity
• The immune system must adapt itself to previously unknown molecules
• After recovery from certain infections ⇢ individuals will never again develop the same infection by the organism
• The individual is now immunised against that organism

Question 6

Active + Passive immunity

Answer 6

Active immunity

• Induction of immunity by infection or w/vaccine

Passive immunity

• Via transferring serum/lymphocytes from immune individual ⇢ non-immune

Question 7

Requirements of immune response

Answer 7

Recognise microorganism as foreign

Respond to microorganism via production of specific antibodies + lymphocytes

Mediate elimination of MO

Question 8

Immune Tolerance

Answer 8

Prevention of immune response against a particular antigen

• Immune system is generally tolerant of self-antigens so it doesn’t attack bodies own self
• If tolerance is lost ⇢ can cause autoimmune disease or food allergy

It is maintained in a number of ways

• When adaptive immune cells mature ⇢ checkpoints are in place to eliminate auto-reactive cells
• Auto-reactive cells are kept in a non-reactive/anergic state
• Regulatory immune cells circulate throughout body to maintain tolerance