Immune System

immune system

provides resistance to disease

IS made up of two intrinsic systems

innate and adaptive

innate

rapid but non specific; have without learning;

adaptive

slower but highly specific; have to be exposed and learn how to fight

innate includes

surface barriers like skin and mucous membrane and internal defenses like phagocytes NK cells inflammation antimicrobial proteins and fever

adaptive includes

humoral immunity like B cells and cellular immunity like T cells

innate immunity first like of defense: surface barriers

skin and mucous membranes produce protective chemicals that inhabit or destroy micoorganisms

innate immunity first like of defense surface barriers: acid

acidity of skin and some mucous secretions inhibits growth called acid mantle

innate immunity first like of defense surface barriers: enzymes

lysozyme of saliva, respiratory mucus, and lacrimal fluid kills many microorganisms; enzymes in stomach kill many microorganisms

innate immunity first like of defense surface barriers: mucin

sticky mucus that lines digestive and respiratory tract traps microorganisms

innate immunity first like of defense surface barriers: defensins

antimicrobial peptides that inhibit microbial growth

innate immunity first like of defense surface barriers: other chemicals

lipids in sebum and dermcidin in sweat are toxic

innate system necessary if microorganisms invade deeper tissues include

phagocytes, NK cells, inflammatory response, antimicrobial proteins, fever

inflammation

triggered whenever body tissues are injured

benefits of inflammation

prevents spread of damaging agents, dispose of cell debris and pathogens, alerts adaptive IS, sets the stage for repair

four cardinal signs of acute inflammation

redness, heat, swelling, pain, impairment of function

stages of inflammation

inflammatory response, vasodilation and increased vascular permeability, phagocyte mobilization

1.) Inflammatory chemical release

inflammatory chemicals flood the extracellular fluid, released by injured or stressed tissues

ex of inflammatory response

mast cells release the potent inflammatory chemical histamine

induces

vasodilation of local arterioles, make capillaries and attract phagocytes to area

2.) vasodilation and increase vascular permeability

brings more cells and chemicals of the immune system to the site of injury or insult; leads to redness and heat

3.) phagocyte mobilization

neutrophils flood area first; macrophages follow

steps for phagocytosis

leukocytosis, margination, diapedesis, chemotaxis

leukocytosis

injured cells release chemicals; triggers release of neutrophils into blood stream from bone marrow

margination

phagocytes cling to inner walls of caps

diapedesis

neutrophils flatten and squeeze between endothelial cells moving into interstitial space

chemotaxis

inflammatory chemicals act as honing device

antimicrobial proteins

variety of antimicrobial proteins enhance our innate defense; most important interferons and complement proteins

interferons

interfere with viruses by inhibiting viral replication

complement proteins

not doing the destroying but complements/helps

fever

help fight infections; abnormally high body temp

pyrogens

send message to hypothalamus to increase temp

benefits of moderate fever

causes live and spleen to hold iron and zinc; increases metabolic rate which increases rate of repair

adaptive acquired immunity

must meet its enemy first begore knowing how to fight

adaptive immunity involves

B and T lymphocytes

adaptive immunity has memory

after initial exposure it recognizes and mounts an even stronger attack than previous

two arms of adaptive immunity

humoral and cellular

humoral immunity

body fluids, antibody mediated (B cells make antibodies), dont destroy antibodies just mark them

cellular immunity

cell mediated, carried by T cells, looking for cells with something wrong, apoptosis

antigen

large signaling molecule, flagged as foreign plants a response

antigenic determinants

parts of antigen that antibodies or lymphocyte receptors bind to

self antigens

all cells are covered with variety of proteins located on surface that are not antigenic to self but may be antigenic to others in transfusion or grafts

MHC proteins

coding for cells that say they belong there

adaptive immune system involves three crucial types of cells

b and c lymphocytes/cells and antigen presenting cells

b lymphocytes (b cells)

humoral immunity; produce antibodies

t lymphocytes (t cells)

cellular immunity

antigen presenting cells

engulf antigens and present fragments to T cells; dendritic cells, macrophages and b lymphocytes

humoral immune response

b cells activate when antigens bind to receptors; make more cells that become plasma cells and effector cells that secrete antibodies

clone cells that do not become plasma become

memory cells that are not producing antibodies but hold onto memories

immunological memory: primary immune response

cell proliferation and differentiation upon expose to antigen for the first time

immunological response: secondary immune response

reexposure to same antigen gives faster more prolonged more effective response

active humoral immunity

occurs when b cells encounter antigens and produce specific antibodies

two types of active humoral immunity

natural acquired and artificially acquired

naturally acquired

formed in response to actual bacterial or viral infection; exposed to chicken pox and build up immunity

artificially acquired

formed in response to vaccine of dead or weaker pathogens ; chicken pox vaccine

passive humoral immunity

occurs when ready made antibodies; passing on immunity

two types of passive immoral immunity

naturally acquired and artificially required

naturally acquired

antibodies delivered to fetus via placenta or to infant through milk

artificially required

injection of serum ; take antibodies from one person and give it to someone else

downside to passive humoral immunity

both dont last long

antibodies/immunoglobulins

proteins secreted by plasma cells

antibodies do not destroy

antigens, they activated and tag them for destruction done by innate defenses

t cells fight cell to cell combat

last resort of fighting infection

two t cells

helper t cells and cytotoxic cells

helper t cells

help dont do any destruction ; release chemical messengers

cytotoxic cells

do the destroying

immunodeficiency

congenital or acquired conditions that impair function or production of immune cells or molecules

acquired deficiency syndrome (AIDS)

HIV cripples IS by interfering with activity of help t cells; weight loss, night sweats, swollen lymph nodes; immune system collapses

autoimmune disease

results when immune system loses ability to distinguish self from foreign

autoimmunity

production of autoantibodies and sensitized t cells that destroy body tissues

autoimmunity examples

rheumatoid arthritis, multiple sclerosis, graves disease, type 1 diabetes, systemic lupus

hypersensitivities

immune responses to perceived threat that cause tissue damage