Immune System

Immune/Lymphatic System

Avenues of Attacks

- Any opening in the body is a point of entry:

- digestive system

- respitory system

- urogenital tract

- breaks in skin

- Routes of attack: how foreginers move around the body once in
- circulatory system

- lymph system

- Why an immune system?

- Attack from outside

- organiams like to feed upon us due to our containement of fats,

lipids, and proteins

- we must protect our cells because cell wall protection has

been traded for mobility

- animals must defend themselves against invaders

- Viruses: HIV, flu, colds etc.

- Bacteria: Pneumonia, meningitis, etc.

- Protistis: amoeba

- Attack from the inside

- when own cells let go of the restrictions of their genitically programed jobs

- ex: cancer cells

- Animals evolved a lymph system

- The production and transprt of leukcytes traps foreign invaders

- Development of Red and White blood cells
- 3 Lines of Defense

- 1st line: barriers

- external defense

- skin and mucus membranes

- 2nd line: non- specific patrol
- broad internal innate defense; attempts to keep everything out

- attacks anything not recognized

- leukocytes = phagocytic WBC

- 3rd line: immune system

- specific aquired immunity

- inherit the ability but aquire defense

- lymphocytes (trained cells) and antibodies

- B cells

- make antibodies

- T Cells

- 1st line: External Defense

- Physical and Chemical Defenses

- non-specific defenders

- External Barrier

- epithelial cells and mucus membranes

- skin

- respiratory system

- digestive system

- uro-genital tract
-Chemical Barriers on epithelium

- Skin and mucous membrane secretions

- acidity in sweat

- tears act as a washing action

- mucus traps microbes

- saliva contains an anti-bacterial

- acidity in the stomach

- anti-microbial proteins

- lysozyme enzyme

- digests bacterial cell walls
- 2nd line: Internal, broad range patrol

- Innate, general defense

- Rapid response

- Patrolling cells and proteins

- they attack invaders that penetrate body's outer barriers

- leukocytes

- phagocytic (engulfing) white blood cells

- Complement system

-Anti-microbial proteins- in blood & plasma

- Inflammatory response

- Leukcoytes: Phagocytic WBC's

- attracted by chemical

- signals released by damaged cells

- enter infected tissue, engulf and ingest microves

- lysosomes

- Neutrophils

- most abundant WBC's

- Macrophages

- "big eater"- long lived

- take pieces of digested invaded and they destroy their cell with it as an alarm

- Natural Killer Cells

- destroy virus-infected cells and cancer cells

- Destroying cells gone bad

- Natural Killer Cells perforate cells
- release perforin protein

- insert into membrane of target cells

- forms pore allowing fluid to flow into cell

- no longer selectively permeable

- cell ruptures

- in flow of liquids into cell causing cell the rupture- apoptosis

- Anti- microbial protein

- 20 proteins circulating in blood plasma

- attacks bacterial and fungal cells

- form a membrane attack complexstamines and prostaglandins

- perforate target cell

- apoptosis

- cell lysis

- Inflammatory Response

- damage to tissue triggers local non-specific inflammatory response `

- release histamines and prostaglandins

- cappilaries dilate - more permeable - all in an attempt to "plug the leak"

- increase blood supply

- delivers WBC, RBC, platelets clotting factors

- fight pathogens

- clot formation

- Fever
-When a local response is not enough

-systemic response to infection

- activated macrophages release interleukin-1

- triggers hypothalamus in brian to readjust body thermostat to raise body temperature (fever)

- higher temperature helps defense

- inhibits bacterial growth

- stimulates phagocytosis

- speeds up repair of tissues

- causes liver and spleen to store iron, reducing blood iron levels

- bacteria need large amounts of iron to grow