RAW (2) IMMUNE RESPONSES

Question 1

Define the non specific immune response

Answer 1

○ Non-specific immune system-
§ Non-specific responses to non-specific diseases
§ Primary defences (eg skin, mucous membranes)
□ Stop stuff from getting in
§ Non-specific immune response (eg inflammation, phagocytosis)
□ What happens after stuff gets in

Question 2

Define the specific immune response

Answer 2

○ Specific immune system -
§ Responsible for “immune response”
§ Specific response to a pathogen
Involves lymphocytes and antibody production

Question 3

What are the 3 types of non specific immune responses and what do they do?

Answer 3

Non-specific immune responses:
1. Physical barriers
○ Skin
§ Physical barrier
§ Produces antimicrobial secretions eg sebum
○ Mucus
§ Traps pathogens in respiratory tract
2. Phagocytosis
○ Pathogen is recognised by phagocyte receptors
○ Phagocyte engulfs pathogen into phagosome
○ Lysosomes fuse with phagosome
§ Release digestive enzymes
○ Pathogen broken down, waste is released
3. Inflammation
○ Infection/injury triggers chemical release (eg histamine) from mast cells
○ Histamines cause vasodilation
§ Increased blood flow to area
○ Increased permeability of blood cells allow immune cells (eg phagocytes) to leak into the tissues
○ Phagocytes move to injury site and engulf pathogens
○ Swelling and pain occur bc of pressure from fluid buildup

Question 4

What are the two types of specific immune responses and what do they do?

Answer 4

Specific immune responses:
1. Cell-Mediated Response (within cells)
○ T-helper cells:
§ Activate B cells to produce antibodies
§ Stimulate phagocytosis and T-killer cells
○ T-killer cells (cytotoxic T cells)
§ Destroy infected cells
○ T-memory cells:
§ Remain in body after infection
□ Faster response when reinfection
2. Humoral immunity (within body fluids)
○ Antigen recognition:
§ B lymphocyte encounters antigen matching its specific receptor
§ Antigen binds to receptor and is engulfed by B cell
○ T-Helper activation:
§ A T-helper binds to antigen on B cell surface
§ T-helper activates B cell
○ Clonal selection
§ Activated B undergoes clonal expansion
□ Forms Plasma Cells
® Secrete large amounts of specific antibodies
□ Forms Memory B cells
® Remain in body for long term immunity
○ Antibody action
§ Antibodies bind to antigens & neutralise pathogens
□ Agglutination
® Clumping pathogens together —> easier phagocytosis
□ Neutralisation
® Blocks toxins & pathogen receptors
□ Opsonisation
Coats pathogens to increase phagocyte recognition

Question 5

Define: phagocyte, phagosome, histamines, mast cell, vasodilation, lysosome, cell mediated and humoral immunity and clonal expansion

Answer 5

Phagocyte - type of white blood cell that engulfs pathogens to destroy them through phagocytosis

Phagosome - vesicle formed inside a phagocytes once it has engulfed a pathogen

Histamines - chemicals released by mast cells during an inflammatory response

Mast cell - type of white blood cell

Vasodilation - the widening of blood vessels

Lysosome - organelle containing digestive enzymes

Cell mediated immunity - type of specific immunity targeting intracellular pathogens

Humoral immunity - type of specific immunity targeting pathogens in body fluids

Clonal expansion - rapid division of activated T or B lymphocyte