Immune System

The body’s defense system

Three Level Approach to Problem

Level I - Non-Specific Defense:

Prevent entry

• Skin

• Mucous Membrane

• Secretions of skin and mucous membranes

Level 2 – Non-Specific Defense:

Search/Destroy at point of attack

foreign objects

• White blood cells

• Antimicrobial proteins

• Inflammatory response

Damaged cells

release chem.

Signals:

histamines

protoglandins

Capillaries dilate

More permeability

Clotting elements

(Platelets) appear

Clotting begin

Phagocytic

leukocytes

enter region

Attracted to

chem. sig.

Leukocytes

consume

pathogens and

cell debris by

phagocytosis

Level 3 - Specific Defense: Complex system of interacting cells

(immune pathway)

Pathogen Macrophage T- Cell

B-Cell Antibodies

Lymphatic system (Protection 3)

Lymph nodes, spleen, tonsils, thymus gland, appendix

Lymph node – contains lymphocytes

(T-cells, B-cells)

-Filters pathogens

-Armpits,neck, intestines….

-get big when infection present

Type of white blood cell

that defends the body

Macrophages identify germs

When a germ invades our bodies, macrophages gobble up

the germ and display its surface shape, or antigen, for other

immune cells to see.

Helper T cells direct the defense

Helper T cells spot the foreign antigen on the macrophage

and begin to multiply. They alert other white blood cells and

direct the body's defense.

B cells make antibodies

B cells start to make chemicals called antibodies. Antibodies

lock onto foreign antigens making it easier for other immune

cells to destroy them.

Killer T cells destroy germs

Alerted by helper T cells, killer T cells multiply and destroy

the invading germs. Working together, our white blood

cells can usually destroy invading germs.

Antibody

An antibody is a

protein used by the

immune system to

identify and

neutralize foreign

objects like

bacteria and

viruses. Each

antibody

recognizes a

specific antigen

unique to its target.

Antibody Immunity

• Antigen – the foreign invader surface proteins

(recognized phagocytes/lymphocytes)

– When an antigen is present, body produces

___________ in response, that are specific

(complementary) to that antigen (shape

matches!)

antibodies

Check out the cartoon

http://www.nyscience.org/whataboutaids/whatis/immune/content.html

What? I don’t understand!

• Macrophage eats pathogen (puts antigen on surface)

• Proteins from antigen are expressed on macrophage surface

• T-cells recognize these antigen proteins as non-self and start signaling

• Some become Killer T-cells – secrete enzymes directly into infected cells and kill them

• Others become Helper T-cells which stimulates more Killer T-cell growth, and stimulates growth of B-cells and their production of antibodies (helper T-cells are like the conductor of an orchestra – telling everyone when and how to play)

Vaccines (Active immunity)– viral protein without genetic

Info. (either from outside of envelope

or the capsid protein itself)

Prepares immune system for future

Attacks, gives time to build up defense

(helps Acquired Immunity)

Vaccines

• Inactivated bacteria or virus

• Provokes immune response but not the

disease or illness

• Memory cells react faster to second

exposure

• Some pathogens mutate too quickly to

be eliminated by vaccines

Antibiotics • Chemicals produced by other organisms (like other

bacteria or fungi) that kill/inhibit bacterial growth (not

viruses!)

• Eg. Penicillin, Ampicillin….

• Harms/prevents formation of bacterial cell wall (makes

holes) – causes water to flow in [from high to low

concentration, remember?] and kills bacterium.