Ch.14 An Intro to Host Defenses and Innate Immunities

innate, natural defenses

present at birth, provide nonspecific resistance to infection. are 1st and 2nd lines of immunity

adaptive immunities

specific, must be acquired. 3rd line of immunity

what does the immune system rely on?

a multilevel network of physical barriers, immunologically active cells, and a variety of chemicals

first line of defense

any barrier that blocks invasion at the portal of entry

second line of defense

protective cells and fluids; inflammation and phagocytosis

third line of defense

acquired with exposure to foreign substance; produces protective antibodies and creates memory cells

which line of defense is the only specific one?

3rd line of defense

3 categories of defenses

• physical or anatomical barriers at the body surface

• chemical defenses

• genetic resistance to infections

built-in defenses in the skin

• outermost layer of ____ with epithelial cells cemented together, and impregnated with keratin

• flushing effect of sweat

• colonized by normal microbes

keratinized skin cells dead

• unable to be infected by viruses

• waterproof

normal microbes occupy _______ niches

ecological

mucous membranes

• coating of digestive, genitourinary, and respiratory tracts

• blinking and tear production

• flow of saliva

• flushing effect of urination, defecation, vomiting

the mucous coat does what?

impedes attachment and entry of bacteria

what happens when bacteria are trapped by mucus?

they are moved against the flow of gravity to the throat where they are either coughed out or swallowed

sebaceous secretions

oily secretion that helps waterproof skin, regulate temp of skin, and decrease sun damage

sebaceous secretions are naturally ________

antimicrobial

surfactant role on skin

causes sweat to coat skin rather than gather in droplets. mixes with oils in skin causes transient bacteria to “slip” off

_________ secreted onto eye with every blink

oily meibum

lysozyme

an enzyme that hydrolyzes the cell wall of bacteria

defensins

peptides that lyse bacteria and fungi

there are high concentrations of _________ and ________ in sweat

lactic acid and electrolytes

skin’s acidic pH

4.5-5.5

__________ acid in the stomach

hydrochloric

humans carrying the gene(s) for sickle-cell anemia are resistant to?

malaria

immunology

study of the body’s 2nd and 3rd line of defense

primary functions of a healthy immune system

• surveillance of the body

• recognition and differentiation of normal versus foreign material

• attack against and destruction of entities deemed to be foreign

white blood cells have the innate capacity for what?

recognition and differentiation of any foreign material

non-self

foreign material that includes cells infected by a virus

self

normal cells of the body

pathogen-associated patterns (PAMPs)

molecules shared by organisms

pathogen recognition receptors (PRRs)

receptors on WBCs for PAMPs

immune cells have _____ on the surface and on their insides that can recognize PAMPs

sensors

body compartments that participate in immune function

• reticuloendothelial system

• extracellular fluid

• bloodstream

• lymphatic system

what is needed for effective immune responsiveness?

activities in one fluid compartment must be conveyed to the other compartments

reticuloendothelial system (RES)

network of connective tissue fibers that interconnects other cells and meshed with the connective tissue network surrounding organs

what is the RES inhabited by?

phagocytic cells, macrophages, and dendritic cells ready to attack and ingest microbes that passed the first line of defnese

whole blood

plasma and formed elements

serum

liquid portion of blood after a clot has formed

plasma

92% water, metabolic proteins, globulins, clotting factors, hormones, and other chemicals and gases to support normal physiological functions

hemopoiesis

production of blood cells

hematopoietic stem cells

undifferentiated cells, precursor of new blood cells

primary classes of progeny

• platelets

• RBCs

• WBCs or leukocytes

what are responsible for immune system function?

leukocytes or WBCs

granulocytes

lobed nucleus, contain granules

agranulocytes

unlobed, rounded nucleus; no granules

types of granulocytes

• neutrophils

• eosinophils

• basophils

• mast cells

neutrophils

lobed nucleic with lavendar granules; phagocytes; first reponders

what do neutrophils do?

phagocytosis

what can neutrophils do?

unravel their DNA and toss it outside of the cell in a process called NETosis

eosinophils

orange granules and bilobed nucleus; destroy eukaryotic pathogensw

what are high levels of eosinophils in blood associated with?

parasitic infection

what does the detection of a parasite cause eosinophils to do?

drop histamine-containing granules

histamine

causes mucus production and smooth muscle contraction

basophils

bilobed nucleic; dark blue granules; release potent chemical mediators

what are basophils and mast cells associated with?

allergies

mast cells

not found in circulation. nonmotile elements bound to connective tissues

types of agranulocytes

• lymphocytes

• monocytes

T cells

modulate immune functions and kill foreign cells

B cells

produce antibodies

macrophages main function

phagocytosis

professional antigen presenting cells (APC)

present pieces (antigens0 of things they’ve eaten to adaptive immune cells

why do dendritic cells do phagocytosis?

for the purpose of presenting antigen to adaptive immune cells

primary function of dendritic cells

antigen presentation

erythrocytes

develop from bone marrow stem cells, lose nucleus; simple biconcave sacs of hemoglobin

platelets

formed elements in circulating blood that aren’t whole cells

what does lymphatic system provide?

an auxiliary route for return of extracellular fluid to circulatory system

what does the lymphatic system act as

a drain-off system for the inflammatory response

small amount of blood plasma squeezes of out vessels with every heartbeat

contains sample of everything in blood l

lymph flows over immune cells into ______

lymph nodes

lymph

plasma-like liquid carried by lymphatic circiulation

when is lymph formed?

when blood components move out of blood vessels into extracellular space

what does lymph transport?

WBCs, fats, cellular debris, and infectious agents

lymphatic capillaries

permeate all parts of body except CNS, bone, placenta, and thymus

_______ easily permeated by extracellular fluid which is then moved though contraction of skeletal muscles

thin walls

function of lymphatic vessels

to return lymph to circulation

lymph flow is _________ meaning towards the heart to the bloodstream

unidirectional

what are the primary lymphoid organs

• thymus

• lymph nodes

• spleen

primary organs

site of lymphocytic origin and maturation. thymus gland and bone amrrow

secondary organs and tissues

circulatory-based locations that encounter microbes. lymph nodes, spleen, MALT, and GALT

tymus

high growth and activity till puberty, then begins to shrink

what is site of T cell maturation

thymus

lymph nodes

Small, encapsulated, bean-shaped organs along lymphatic channels and large blood vessels of the thoracic and abdominal cavitie

what do lymph nodes filter?

lymph; provides niches for adaptive immune cell activation

spleen

Structurally similar to lymph node; filters circulating blood to remove worn out RBCs and pathogens

mechanisms that play important roles in host defenses

inflammation, phagocytosis, interferon, and complement

inflammatory response

reaction to any traumatic event in the tissues that attempts to restore homeostasis

what happens when tissue damage causes inflammation?

Damage Associated Molecular Patterns (DAMPs)released and detected by the immune system

4 cardinal signs of inflammation

1. redness

2. warmth

3. swelling

4. pain

redness (rubor)

increased circulation and vasodilation in response to chemical mediators

warmth (color)

heat given off by increased blood flow

swelling (tumor)

increased fluid in the tissues as blood vessels dilate

pain (dolor)

stimulation of nerve endings

major inflammatory events

• injury/immediate reactions

• vascular reactions

• edema and pus formation

• resolution/scar formation

injury/immediate reactions

blood vessels narrow; blood clots; and mast cells release chemokine and cytokines into injured area

chemokines

small proteins that recruit cells to damaged/infected areas

cytokines

small proteins that tell cells how to behave

vascular reactions

nearby blood vessels dilate; increased blood flow; increased vascular permeability; increased leakage of fluid forms exudate

edema and pus formation

collection of fluid; edema/swelling; infiltration by neutrophils; and formation of pus

resolution/scar formation

macrophages, lymphocytes, and fibroblasts migrate in; initiate immune response and repair of injury; scars and loss of normal tissue

chemotaxis

migration in response to specific chemokine, realized at the site of injury or infection