Immune System

what is a pathogen

organism that causes disease in it’s host

what is an infection

pathogens enter the body and begin to multiply

what is a disease

when cells in the body are damaged and signs/symptoms of illness appear

describe the innate immune system

provides non-specific defenses, 1st, 2nd, and 3rd lines of defense, the immune system we are born with

describe the adaptive immune system

provides specific defenses, targeting specific pathogens, the immune system we aquire

what are the first line defenses of the Innate immune system

physical barriers- skin and mucous membranes

chemical barriers- gastric juice, lysozymes (enzyme that breaks down pathogens) in tears and saliva, and acid in urinary tract (and vagina)

what are the cellular defenses

leukocytes (white blood cells): granulocytes and agranulocytes

what are granulocytes

leukocytes that can release granules (chemicals and enzymes) that are toxic to pathogens

what are the three types of granulocytes

Basophils, eosinophils, neutrophils

describe the function of basophils

defend against PARASITES, release histamine; allergic response

what does histamine do

makes capillaries more permeable, makes things swollen looking

describe the function of eosinophils

kills PARASITES, also involved in inflammation and autoimmune disorders; release histamine, is a PHAGOCYTE

describe the function of neutrophils

PHAGOCYTOSIS, especially of BACTERIA

what is the list of agranulocytes

monocytes, macrophages, dendritic cells, mast cells, natural killer cells

describe a monocyte

phagocyte, clears pathogens, primarily in blood stream and spleen

macrophage function

PHAGOCYTE, resides in tissues

describe the function of dendritic cells

PHAGOCYTES, major antigen-presenting cell, activates certain types of T-cells

describe the function of mast cells

release histamine in response to allergens, immune cells of skin and mucosa

describe the function of natural killer cells

attack VIRUS-infected cells, cancer cells; secrete perforins that lyse infected cells, early immune response

where are granulocytes and agranulocytes derived from

hematopoietic cells in the bone marrow

what immune cells are phagocytes

eosinophils, neutrophils, monocytes, macrophages, and dendritic cells

describe the steps of phagocytosis

attachment- specific: damaged cells or protein-targeted cells, proteins = opsonins

internalization- takes approx. 0.01 sec, phagosome + lysosome = secondary lysosome

degradation- lysosome enzymes degrade phagocytosed product

exocytosis- elimination of some degradation products

what are the 3rd line defenses

non-cellular defenses: fever, inflammation, interferons, the complement system

describe the process of a fever

stimulates phagocytosis, stimulates liver and spleen to remove iron from the blood (required for microbe metabolism)

what does inflammation do

series of events causing accumulation of proteins, fluid, and phagocytes in an injured or invaded area

• macrophages engulf debris and foreign matter = initiation step

• capillaries dilate and become more permeable (more fluid out of the blood stream and into the tissues, more proteins, fluid and cells to injured tissue)

• foreign matter is contained

• more leukocytes migrate to area

• leukocytes clear infection

symptoms of inflammation

Heat, pain, edema/swelling, redness (HPER)

how does capillary exchange happen in the lymphatic system

by diffusion, exchange by bulk flow

• capillaries have low permeability to protein (osmotic effect)

• hydrostatic pressure decreases as blood passes through

• the net outward pressure is higher at the arteriole end and lower at the venule end of the capillary, so fluid moves out of the arteriole end and moves in at the venule end

what is the fluid called that is moved into the tissues

interstitial fluid

what is the interstitial fluid called when it is absorbed into lymph circulation

lymph

what is edema

fluid accumulation in tissues, can result from decrease in blood protein concentration (therefore decrease osmotic pressure in the blood)

what is ascites

edema (abnormal build up of fluid) in abdominal cavity

elephantiasis

usually caused by parasitic infection of lymphatic system

functions of the lymphatic system

transport and filter interstitial fluid, transport biomolecules (in chyle), initiate an immune response to found pathogens, drains excess tissue fluid

describe lymph

clear fluid of lymphatic system that forms from interstitial fluid

describe lymphatic capillaries

drains fluid away from tissues

describe lymph vessels and ducts

collect lymph from capillaries and carry the lymph toward the subclavian veins

describe lymph nodes

filter lymph that passes through, cleaning it before it’s mixed with the blood

describe the subclavian vein

lymph returned to general circulation here

does the lymphatic system have a pump

no

what do valves do

ensure one-way flow

how is force provided for lymph flow

muscle contraction

what are lymph vessels paired to

arteries, arteries and pulsation in arteries assist with lymph flow

what is lymph exposed to in the lymph nodes

lymphocytes and macrophages

how does lymph flow in the entire body

left subclavian vein- left side of body and lower right quadrant

right SV- upper right quadrant

why are macrophages important in the lymphatic system

they ingest bacteria and debris from lymph before fluid gets returned to general circulation to help prevent spread of infection

why is bone marrow important

site of B-cell maturation (B-cells make antibodies, type of lymphocyte)

why is the thymus gland imporant

site of T-cell maturation (T-cell are other type of lymphocyte)

where do B+T cells go after maturation

migrate to peripheral lymphoid tissues (spleen and lymph nodes)

what does the spleen do

filters and refines blood, recycles red blood cells, macrophages and lymphocytes are concentrated in spleen among other peripheral lymphoid organs

which system takes hours to activate, broad action and has both cellular and non-cellular defenses

innate immune system

which system takes days to activate, antigen specific, and has humoral or cell-mediated immunity

adaptive system

how are infected cells and specific pathogens identified

by their antigens= chemical signals that initiate immune response

what are the recognition sites on antigens called

epitopes

where are antigens typically found

on the outer coat, cell wall, or membrane

what do B+T cells have on their surface

receptors that bind to antigens

what are B cell receptors

antibodies- antibodies can also be free found floating in the blood plasma

what is humoral (B-cell) immunity (humors =body fluids)

involves antibody production from plasma cells, produces memory B cells so response can be initiated if re-exposure occurs

what is the antibodies structure

two heavy chains, two light chains, constant region (same within class of antibodies), variable region (differs for different antigens, gives specificity to antigen binding site), two identical antigen binding sites -bind to 2 recognition sites of the same kind, one antibody is specific for a particular antigen, but many antibodies confer DIVERSITY- and allow for recognition of millions of antigens of the body’s immune system

what do antibodies function to do

• neutralize antigen- binding to Ab. blocked the activity of pathogen

• agglutinate antigen- multiple pathogens aer aggregated together and rendered ineffective

• opsonization- pathogens can be marked/tagged for destruction by antibodies, making them more efficiently engulfed by phagocytes

• activate compliment

• enhance natural killer cells

B cells also undergo clonal selection, what is it?

• this is a type of positive selection, letting develop only those cells that can bind to antigen

• b cells are activated by binding to antigen, then proliferation (make many copies) and differentiate into two types of cells

  • short lived effector cells called plasma B cells that produce antibodies

  • memory B cells that can last in the body for years

what does immunological memory result in

faster responses upon re-exposure

what are features of specific response

specificity, diversity, memory, self-tolerance

what is positive selection

maturing only cells that can bind to antigens