the immune system

Non-specific/innate VS specific/adaptive

INNATE:

• attack all foreign microbes

• DOES NOT RETAIN MEMORY

• Usually present from birth

ADAPTIVE:

• recognises specific pathogens from previous infections

  • Rapid response

• Can address infections around the whole body

Name the 5 types of main non-specific defences (P.I.I.NE)

P: phagocytosis

I: immunological surveillance

I: inflammatory response

N: natural anti microbial substances

E: epethilial barriers

What are memory B cells

• live longer

• Provide immunity by responding quickly to previously encouraged antigens

• recognise and bind to antigens directly and produce antibodies

1st line non specific defence: epethilial barriers (C.U.N.S.S) — prevents entry of foreign microbes

• Cilia: moves mucus + inhaled materials to throat — coughed up/swallowed

• Urine: one way flow. Minimise risk of infection.

• Nose hair: filter system. Stops foreign materials entering respiratory tract.

• Sweat: contains antibacterial properties.

• Skin: barrier against pathogens.

2nd line non-specific defence: antimicrobial substances (S.H.L.A.I)

Saliva: washes away antibodies

Hydrochloric acid: digests harmful antibodies in stomach

Lyzomes: found in teas and other bodily fluids.

Antibodies: bind to and destroys antigens

Interferons: activate immune cells. Prevent viral replication. Reduce spread of virus to healthy cells.

phagocytosis (M.N)

• attack, digest and destroy foreign cells

Neutrophils:

• most abundant type of WBC — first responders

• Self destructive — once activated = destroy themselves

Macrophages:

• live longer

• After phagocytosis of an antigen, they displayed fragments of that antigen on their membrane — activates T cells — activates adaptive immune system.

• Production and recruitment of neutrophils

inflammatory response

Occurs in response to injury or infection

• purpose: inactive damaged tissues so healing can take place

Inflammatory response:

SCENARIO: needle with bacteria enters the skin

• Mast cells release histamine molecules

• Inflammatory mediators causes vasodilation — capillaries become larger. Fluid fills them up (responsible for redness that in inflammation — signs of healing)

  • EG: Increased temp: increase metabolic rate = faster repair

• Histamines, chemokines (chemicals) being release into capillaries

• Chemotaxis: chemical attraction of leukocytes (neutrophils and macrophages) WBC move towards these chemicals

  • Squeeze through capillary walls

  • Neutrophils — phagocytosis takes place. Engulf the bacteria that entered the body

What are the roles of the NK cells

• patrol the body of abnormal host cells and kill infected cells

What imitates the expansion of T cells?

• the recognition of a specific antigen presented by APC (antigen presenting cell)

Describe the difference between T cells and B cells

• both produced in bone marrow however, T CELLS mature in thymus (thymosine hormone which stimualtes maturation and B CELLS mature in bone marrow

• T cells provide CELL MEDIATED IMMUNITY

  • Consist of:

    • Cytotoxic: directly inactive the cell

    • Helper: secretes cytokines to support cytotoxic cells

• B cells provide (ANTIBODY MEDIATED IMMUNITY)

• B cells produce antibodies (immunoglobulins)

  • Biden the and destroy antigens

Cell mediated immunity! Diagram (explain what is happening)