Exam 4

innate immunity

nonspecific defenses, first responders, born with this, recognizes pathogens by predetermined patterns; Toll-Like Receptors (TLR), no memory, first and second line of defense

adaptive immunity

develop as you grow, second to respond, clears infections, learns and remembers each pathogen encountered, memory to previously encountered pathogens, acts faster, third line of defense

first line of defense

physical barriers to prevent microbial entry: skin, mucous membranes, ciliary escalator

first line of defense: skin

largest physical barrier; keratin: skin, nails, hair; epithelial cells tightly packed, tough layer that few pathogens can penetrate

first line of defense: mucous membrane

prevent entry and attachment of bacteria, layer of epithelial cells, secrete mucous; gastrointestinal, genitourinary, respiratory tracts; invasins help bacteria get through the mucous membrane

invasins

helps bacteria get through the mucous membrane

first line of defense: ciliary escalator

found in different parts of the respiratory tract, cilia and mucous help trap microbes, sneezing and coughing releases microbes, smoking damages cilia which increases respiratory infections

first line of defense physical factors

saliva, urine, vaginal secretions, lacrimal apparatus, defecation, vomiting

physical factor saliva

washes microbes off, carries microbes to acidic stomach

physical factor urine

flows out, moves microbe out of the body

physical factor vaginal secretions

flow out removing microbes

physical factor lacrimal apparatus

washes eyes

first line of defense chemical factors

sebum, gastic juices, vaginal secretions, lysozyme

chemical factor sebum

lowers pH of skin, inhibiting microbial growth

chemical factor gastric juices

include HCl, lowers pH of stomach, acidity inhibits and destroys some microbes

chemical factor vaginal secretions

lowers pH of vagina and inhibits microbial growth

chemical factor lysozyme

found in secretions like saliva, tears, perspiration; digest peptidoglycan of some bacterial cells

normal flora

compete with pathogens via microbial antagonism (competitive exclusion)

why is normal flora part of the innate immune system

it can inhibit the growth of other microbes and stops bacteria from colonizing

second line of defense cells

RBC, WBC: granulocytes and agranulocytes

granulocytes

mainly innate, leukocytes with granules in their cytoplasm that are visible with a light microscope; neutrophils, basophils, eosinophils

granulocytes examples

neutrophils, basophils, eosinophils

neutrophils

first responser, the first cells to the site of infections, type of phagocyte

basophils

release histamine and are involved in allergies

eosinophils

killing parasitic worms and allergies, have some phagocytic activity

agranulocytes

leukocytes with granules in their cytoplasm that are not visible with a light microscope

agranulocytes examples

monocytes, dendritic cells, lymphocytes

monocytes

can mature into macrophages, seen in blood

macrophage

phagocyte that performs phagocytosis

dendritic cells

phagocytes that perform phagocytosis, derived from monocytes, larger role in adaptive immunity

lymphocytes

T cells, B cells, natural killer cells

T cells

cell mediated immunity, cells activated and perform function

plasma cells

make antibodies

natural killer cells

kill cells, non-specific killers, can kill worms or infected cells, innate but can be adaptive

T cell and B cells

which agranulocytes are involved with adaptive immunity

differential white blood cell count

Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils

components of the lymphatic system

lymphatic vessels, primary lymphoid organs, secondary lymphoid organs

lymphatic vessels

contain lymph, WBC, antibodies

primary lymphoid organs

thymus and bone marrow

secondary lymphoid organs

spleen and lymph nodes

thymus

where do T cells mature

red bone marrow

where do B cells mature

lymph node

throughout body so that phagocytes with pathogen dont have to travel far, activation of T cells

second line of defense: innate immune cells

neutrophils, monocytes, basophils, macrophages, eosinophils, natural killer cells

second line of defense: what they do

phagocytosis, inflammation, fever, antimicrobial substances (complement), cytokines

TLR

toll-like receptors

toll-like receptors

found on the surface of phagocytes and inside vesicles that are inside the cell, bind to the PAMP

pathogen associated molecular patterns

PAMP

PAMP

is only present on the pathogen

PAMP examples

lipopolysaccharides, flagellin, peptidoglycan, teichoic acids, viral RNA, viral DNA

cytokines

proteins that send signals to different parts of the immune system; results in phagocytosis of pathogen

how does the innate immune system recognize pathogens

once TLR binds to the PAMP, that causes the phagocyte to release cytokines

phases of phagocytosis

chemotaxis, adherence, ingestion, phagosome, phagolysosome, digestion, discharge, presentation

phagocytosis: chemotaxis

signal phagocyte is attracted to, chemical attraction of the phagocyte to the microbe, chemotactic factors can attract phagocytes

phagocytosis: adherence

TLR on the phagocyte bind to the PAMP on the microbe

phagocytosis: phagosome

formation of the microbe and phagocytic vesicle

phagocytosis: phagolysosome

fusion of the phagosome with a lysosome

lysosome

organelle containing digestive enzymes

evade phagocytosis examples

protein A, M protein, capsule, leukocidins, mycolic acid

inflammation

second line of defense, can occur during an immune response, signs and symptoms: redness, warmth, swelling, pain;

three stages of inflammation

1. vasodilation and increased permeability of blood vessels

2. phagocyte migration and phagocytosis

3. tissue repair

2. phagocyte migration and phagocytosis

3. tissue repair

histamine

causes increased permeability of blood vessels

so that certain molecules like WBC can be released to the site of infection

why does vasodilation and increased permeability of blood vessels occur during inflammation

fever

increase in internal body temperature to levels that are above normal; inhibit microbial growth of some microbes; help stimulate immune reactions; activated by endotoxins

fever caused by

infection from bacteria, their toxins, or viruses

endotoxins

what are fevers activated by

second line of defense

what line of defense are fevers part of

antimicrobial substances

complement (C') in the blood; made by leukocytes to kill microbes: interferons

complement system

innate, 30 proteins made by the liver which circulate in the blood and are only functional when activated, activation is a cascade of ordered interactions between these proteins, 3 outcomes of complement activation

activated protein fragments

C3b, C3a

inactive protein fragments

C3, C2, C1

three outcomes of complement activation

opsonization, inflammation, cytolysis

classical pathway

antigen-antibody complex with C1; C1 activates C2 and C4; C2 split into C2b and C2a; C4 split into C4b and C4a; C2aC4b combine and activate C3; C3 split into C3a and C3b

inflammation

C3a function in all pathways

cytolysis and opsonization

C3b function in all pathways

alternative pathway

lipid-carbohydrate complex on the surface of the microbe as it binds to C3 through the complement proteins: factor B, factor D, factor P; C3 splits into C3a and C3b

lectin pathway

mannose-binding lectin binds to the mannose on the surface of the microbe which activates C2 and C4; C2 split into C2b and C2a; C4 split into C4b and C4a; C2aC4b complex activates C3; C3 splits into C3a and C3b

complement activation outcome: cytolysis

C3 splits into C3a and C3b; C3b activated and splits into C5; C5 splits into C5a and C5b; C5b combines with C6, C7, C8, C9 to form the membrane attack complex (MAC) on the membrane of the pathogen

membrane attack complex (MAC)

results in cytolysis which causes lysis and death of the pathogen, a pore, attacks plasma membrane

gram-negative bacteria

which bacteria are susceptible of the membrane attack complex

complement activation outcome: opsonization

C3 splits into C3a and C3b; C3b acts as an opsonin and binds to the pathogen to coat the pathogen and enhance phagocytosis

opsonin

protein that can coat the pathogen and enhance phagocytosis making it easier for the phagocyte to adhere to the microbe through its C3 receptors

opsonin examples

C3b and antibodies

complement activation outcome: inflammation

C3 splits into C3a and C3b; C3a binds to the C3a receptors on a mast cell, C3b splits into C5; C5 splits into C5a and C5b; C5a binds to the C5a receptors on the mast cell causing the mast cell to release histamine from granules (degranulation)

chemotactic factors

attract phagocytes to site of inflammation

chemotactic factors examples

C5a and C3a

interferon-gamma

activates neutrophils and macrophages to kill microbes by causing an increase in phagocytosis

interferon-alpha and interferon-beta

produced by cells in response to viral infections and cause neighboring cells to produce antiviral proteins (AVPs) that inhibit viral replication, help fight off viral infections, signaling molecules, produced by infected cells

antiviral proteins

AVPs

antiviral action of alpha and beta interferons

virus induces infected host cell to produce alpha and beta interferons; interferons released from infected cell and make contact with uninfected neighboring host cell; interferons induce uninfected neighboring cell to synthesize antiviral proteins; AVPs in uninfected neighboring cell will degrade viral mRNA and inhibit protein synthesis

acquired immunity

what is adaptive immunity also known as

stem cells

can differentiate into B cells and T cells, will migrate to different lymphoid organs where they can perform their specific function

thymus

T cells mature here

red bone marrow

B cells mature here

adaptive immunity types

humoral immunity and cellular immunity

humoral immunity

B cells and antibodies, B cells have a B cell receptor (BCR) on the surface of the cell, antibodies outside cell circulating for a pathogen

cellular immunity

T cells have a T cell receptor (TCR), T Helper cell, cytotoxic T cell (CTL), focusing on destroying intracellular pathogens

antigen

protein or polysaccharide recognized by the immune system, components of invading microbes or foreign substances