Ch 21- the Immune system

Immunity

the ability of the body to defend itself against unfamiliar microorganisms

2 intrinsic systems of immunity

innate and adaptive defenses

innate defenses

non-specific, no previous exposure, physical barriers

innate defense lines

surface barriers and cells/chemicals

cells and chemicals of innate defenses

antimicrobial proteins and macrophages

surface barriers

physically prevent pathogens from entering body

types of surface barriers

skin, mucous membranes

parts of skin barrier

keratin and acid mantle

keratin

tough protein resistant to weak acids, weak bases, bacterial enzymes

acid mantle

sweat and sebum on skin surface are slightly acidic, bactericidal

mucous membranes

line all body cavities that open to the exterior ( digestive, respiratory, reproductive tracts)

parts of mucous membranes

mucus, nasal hairs, cilia, acid mantle, tears, saliva, urine

mucus

traps microorganisms in respiratory and digestive tracts

nasal hairs

trap microorganisms in nasal cavity

cilia

takes mucus with trapped microorganisms and propels away from nasal cavity and respiratory tract

parts of acid mantle

stomach and vagina

stomach

secretes very acidic gastric juices

vagina

acidic nature prevents bacterial and fungal growth in reproductive tract

tears and saliva

cleanses eyes and mouth with lysozymes

urine

acidic in nature, physically removes bacteria during urination

cellular and chemical defenses

used when surface barrier is breached

skin and mucous membranes can

can suffer physical damage

pattern recognition receptor is apart

apart of cellular and chemical defenses

pattern recognition receptor

proteins found on cells of the immune system

pattern recognition receptor function

recognize potentially harmful substances by presence of a molecule with a certain shape found on pathogen

cells of innate defense

NK and phagocytes

NK cells

target cancerous cells and virus infected cells

NK characteristics

non-specific, non-phagocytic, induces apoptosis

NK release perforin

creates pores in the membrane to induce apoptosis

examples of phagocytes

neutrophils and macrophages

phagocytosis

process by which cell engulfs and destroys pathogenic cells or substances

neutrophils

become phagocytic upon encountering pathogen using defensins to induce lysis

macrophages types

free and fixed

free macrophage

capable of traveling through tissue to search for pathogens

fixed macrophages

permanent location in tissue of a particular organ

phagocytosis not always successful reasons

resistant to lysosomes, capsule, too large

pathogens are resistant to phagocytic lysosomes solution

release respiratory burst, free radicals, oxidizing chemicals

surrounded by capsule

phagocyte cannot recognize infectious organism

bacteria capsule solution

opsonins solution

opsonins

substance binds to pathogen surface that allows to recognize and bind

examples of opsonins

antibodies and complement

too large solution

release toxic chemicals in ECF killing it and surrounding healthy cells

inflammation

nonspecific localized response to tissue injury, cells and chemicals

inflammation symptoms

redness, heat, swelling, pain, maybe impaired function

benefits of inflammation

prevents spread, dispose debris, alerts immune system, allows repair

inflammatory chemicals

histamine, kinins, prostaglandins

histamine

released by basophil, vasodilation, increased capillary permeability

kinins

derived from plasma protein kininogen, vasodilation, attracts leukocytes, induces pain

prostaglandins generated by

generated by neutrophils, basophils, mast cells,

prostaglandins effect

vasodilation, neutrophil chemotaxis, induces pain

4 step neutrophil and macrophage mobilization

leukocytosis, margination, diapedesis, chemotaxis

leukocytosis

an increase in number of white blood cells in blood

leukocytosis inducing factors released

released by injured cells

margination

phagocytes cling to inside of endothelial wall of capillaries at the injury site

diapedesis

cells cling to wall will squeeze between cells of endothelial wall

chemotaxis

inflammatory chemicals are chemotactic agents

phagocytes and WBC use

use positive chemotaxis to local injury

monocytes take longer

longer to be mobilized and form macrophages

benefits of monocytes taking longer

can replace worn out neutrophils, dispose debris

innate antimicrobial proteins

proteins that can attack microorganisms directly or interfere with their reproduction

types if antimicrobial proteins

interferons, complement

interferons

released by cells infected by virus to protect noninfected cells

interferons pathway

diffuse into local cell, noninfected cell synthesizes proteins to degrade viral RNA to not be able for viruses to replicate itself

complement

group of 20 plasma proteins by liver

complement characteristic

inactive in blood

role of inflammatory reaction

activation, stimulates phagocytes, lyse

activation of complement

causes massive release of inflammatory chemicals

fever

body-wide systemic response to pathogens

fever cells

leukocytes and macrophages release pyrogens

pyrogen function

reset hypothalamus body temperature

low grade temperature

99-100..4 24hrs+

103 in children

causes stroke and seizure

benefits of fever

causes spleen and liver to store more Fe away from bacteria, increases metabolic rate of tissue to speed up repair

adaptive defenses

specific, slower, must be exposed to antigen before reaction

features of adaptive defenses

humoral and cellular immunity

humoral immunity

antibodies present in body’s fluids, circulate freely after release to mark and inactivate target cells

cellular immunity

lymphocytes directly defend body by killing or increasing inflammation and active macrophages

differences in adaptive and innate defense

adaptive defenses lymphocytes, more specific, systemic, has memory

antigens

any substance that can mobilize the adaptive defense system to recognize self vs non self

types of antigens

complete vs incomplete

complete antigens/ immunogenic

stimulate lymphocyte proliferation and generate immune response, react with lymphocyte and antibodies

acts as complete antigen

proteins, polysaccharides, lipids, nucleic acids

hapten/ incomplete antigen

can only generate immune response when attached to protein carrier to recognize non-self

examples of hapten/incomplete antigen

poison ivy, pet dander, detergents

to begin immune response, lymphocytes and antibodies must

must bind to antigenic determinants of antigen surface

one antigen can have

can have several determinants on its surface with different shapes

antibodies and lymphocytes can only

only recognize one antigenic determinant

self-antigens

antigens that belong to your own body, individual basis

Major histocompatibility complex proteins

class of glycoprotein found on the surface of our cells, for class of proteins, hold antigen

gene code for class of proteins

highly unlikely that 2 individuals have exact set of genes

cells of adaptive defenses

lymphocytes, antigen-presenting cells

lymphocytes

B and T cells, must mature before they can launch

lymphocyte maturation steps

originate from stem cells, education, seeding/circulation, antigen exposure, proliferation

lymphocyte education

immunocompetence, self-tolerance

immunocompetence

lymphocytes must be able to recognize a single antigen to act against, specific

self-tolerance

lymphocytes must be able to recognize self vs non-self

seeding and circulation

B and T cells colonize secondary lymphoid organs, circulate body

antigen exposure

first encounter with antigen leads to clonal selection