Immune System

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Disease

failure of homeostasis

causes of disease

1. genetic
2. pollutants
3. harmful lifestyles
4. microorganisms

pathogens

disease causing organisms

pathogens enter the body through:

1. respiratory pathway
2. digestive system
3. urethra
4. breaks in the skin

first line of defense

physical and chemical barriers

physical barriers

skin membranes

chemical barriers

sweat, tears, saliva, mucus, stomach acid, urine

second line of defense

inflammatory response

the inflammatory response

non-specific defense or innate

involves phagocytes

the reaction causes swelling, redness, warmth, and pain in an area of infection

Phagocytes

type of white blood cells that do phagocytosis

Events of the inflammatory response

1. blood cells near the wound or infection expands and white blood cells leaks from the vessels to enter the infected tissue
2. phagocytes are attracted to the area and engulf the bacteria
3. chemicals are released which cause a rise in body temp (fever)

Increases temperature help:

slow the growth of pathogens

increase the rate of chemical reactions that kill pathogens

increases heart rate so white blood cells get to the infection faster

third line of defense

the immune system

the immune system

involves white blood cells:


1. phagocytes
2. lymphocytes (B cells, helper T cells, killer T cells)

antigens

any substance that triggers the immune system

antibody

protein produced by the immune system that helps destroy pathogens

2 types of immune response

1. humoral response
2. cell mediated immune response

humoral response

1. the antigen comes in contact with the WBC and activates it
2. chemicals are released
3. chemical cause white blood cells to divide rapidly forming identical cells
4. 1/2 of the WBC make antibodies
5. 1/2 remain inactive and become memory cells

antibodies characteristics

shaped like the letter y and have two binding sites

each antibody is custom made for a specific antigen

antibodies attract phagocytes which engulf both the antibody and the antigen

cell-mediated immune response

other types of WBCs called T-cells attack antigens by transferring proteins into the cell membrane of the infected cell causing fluid to leak out: cell ruptures and dies

vaccination

injection of a weakened form of a pathogen to produce immunity

types of immunity

1. active immunity
2. passive immunity

active immunity

1. body produces it’s own antibodies to attack an antigen
2. usually the result of contracting the disease
3. can also develop through a vaccination
4. (long-lasting/permanent immunity

passive immunity

1. person is given antibodies (borrowed immunity)
2. temporary (about a month)
3. maternal immunity: antibodies from the mother enters the baby’s blood before birth; or are transmitted through breast milk

ABO blood groups

A, B, AB, O

A

A antigens; B antibodies

B

B antigens; A antibodies

AB

A+B antigens; no antibodies

O

no antigens; A and B antibodies

A can recieve these blood types

A, O

B can recieve these blood types

B, O

AB can recieve these blood types

A, B, O, AB

O can recieve these blood types

O

Transplants

1. recognized by the recipient as foreign (antigen) and the immune system response is activated
2. Transplants are destroyed in a process called rejection unless the donor-recipient are closely related and immune suppressant drugs are used

allergies

1. rapid reaction to an antigen that is not normally harmful
2. when allergens bind to mast cells they release histamine which causes symptoms (runny nose, swollen eyes, itching, sneezing, coughing, rash)
3. allergic reactions may cause asthma

AIDS (aquired immunodeficiency syndrome)

**cause: human immunodeficeny virus (HIV) which is spread by the exchange of bodily fluids**


1. HIV infects helper T cells and may remain in cells for months or years without producing syndromes
2. when HIV becomes active it reproduces and destroys helper T cells
3. immune system weakens
4. symptoms include: swollen lymph node, glands, fever, weakness, unexplained weight loss, frequent infections such as pnuemonia

cancer

1. T cells search the body and destroy cancer cells in healthy people
2. suppression of the immune system in HIV can result in cancer
3. other causes of cancer include: viruses, radiation (ex. UV light from the sun), and chemicals (ex. tobacco)