CH 16 Innate Immunity Nonspecific Defenses of the Host

susceptibility

lack of resistance to a disease

immunity

ability to ward off a disease

innate immunity

defenses against pathogens that are present at birth

adaptive immunity

• immunity

• resistance to a specific pathogen

• slower to respond

• has memory component

immunity levels (outside to inside)

1. mucous membrane, skin, antimicrobial substance

2. inflammation, fever phagocytes

3. humoral and cellular immunity

white blood cell counts measure

leukocytes in blood

high WBC indicate

• bacterial infections

• autoimmune diseases

• side effects of medications

low WBC

• viral infections

• pneumonia

• autoimmune diseases

• cancers

skin and mucous membranes physical factors

barriers to entry or processes that remove microbes from the body’s surface

skin and mucous membranes chemical factors

chemicals that inhibit or destroy microbial growth

dermis

• inner portion of skin

• made of connective tissue

epidermis

• outer portion

• made of tightly packed epithelial cells

• contains keratin - protective protein

mucous membranes

epithelial layer that lines gastrointestinal, respiratory, and genitourinary tracts

secret mucus

traps microbes and prevents tracts from drying out

other physical factors that help protect epithelial surface

• lacrimal apparatus

• ciliary escalator

lacrimal apparatus

tears wash away microbes

ciliary escalator

microbes trapped in mucus are transported away from the lungs

earwax

prevents microbes from entering the ear

saliva

washes microbes off

urine and vaginal secretions

flows out

sebum

substance produced by the oil glands

pH of sebum

3-5

sweat glands

perspiration

normal microbiota

compete with pathogens via microbial antagonism

methods and purpose of competition

• compete for space and nutrients

• produces substances harmful to pathogens

• alters conditions that affect pathogen survival

second line of defense

• phagocytic cells

• inflammation

• fever

• antimicrobial substances

formed elements in blood

• RBC

• WBC

  • granulocytes

  • agranulocytes

• platelets

granulocytes

leukocytes with granules in cytoplasm that are visible with a light microscope

neutrophils (neutral loving)

• phagocytic

• work in early stages of infection

• first responder to infection

• 60-70% of WBC

basophils (base loving)

• 0.5 - 1% of WBC

• produce histamine

• work in allergic responses

eosinophils (acid loving)

• 2.4% of WBC

• kill parasites

agranulocytes

leukocytes with granules in cytoplasm that are NOT visible with a light microscope

monocytes

• 3-8% of WBC

• respond quickly to infection

• develop into macrophage

• phagocytosis

dendritic cells

• derived from monocytes

• phagocytosis

• found in the skin

• mucous membranes

• thymus

• phagocytic

lymphocytes

• 20-50% of WBC

• plays a role in adaptive immunity

lymphocytes contain

• natural killer cells

• T cells

• B cells

natural killer cells

destroys target cells

T cells

cell-mediated immunity

B cells

produce antibodies

what happens when an infection occurs

granulocytes (esp neutrophils) and monocytes migrate to the infected area

monocytes develop into

macrophages

2 types of macrophages

• fixed macrophages

• wandering macrophages

fixed macrophages

residents in tissues and organs

wandering macrophages

roam tissues and gather at sites of infection

phagocytosis steps

1. chemotaxis and adherence of microbe to phagocyte

2. ingestion of microbe by phagocyte

3. formation of a phagosome

4. fusion of phagosome with a lysosome to form a phagolysosome

5. digestion of ingested microbe by enzymes

6. formation of residual body containing indigestible material

7. discharge of waste materials

chemotaxis

chemical attraction

imflammation

damage to body’s tissues triggers a local defensive response

inflammation symptoms

• redness

• pain

• heat

• swelling

• loss of function

types of inflammation

• acute inflammation

• chronic inflammation (TB)

function of inflammation

• destroy the injurious agent

• limit the effects on the body

• repair or replace tissue damage

inflammation activates

acute-phase proteins by the liver

acute-phase proteins cause

• vasodilation

• increased permeability

examples of acute-phase proteins

• histamine

• kinins

• prostaglandins

• leukotrienes

• cytokines

process of inflammation

• vasodilation

• phagocyte migration

• phagocytosis and tissue repair

vasodilation

dilation (increase in diameter) of a blood vessel

purpose of vasodilation

increases blood flow to the damaged area

vasodilation causes

redness and heat associated with inflammation

increased permeability

permits defensive substances normally retained in blood to pass through the walls of the blood vessels and enter the injured area.

edema

accumulation of fluid (swelling)

margination

sticking of phagocytes to blood vessels in response to cytokines at the site of inflammation

diapedesis

endothelial cells of blood vessels where phagocytes squeeze in

fever

abnormally high body temp

hypothalamus sets body thermostat at

37 C

to raise body at a high temp, the hypothalamus

releases prostaglandins that reset the hypothalamus to a high temperature

advantages of a fever

• increases transferrins

• increases IL-1 activity

• produces interferon

transferrins

decreases the iron available to microbes

IL-1

helps production of T cells

interferon

antiviral protein

disadvantages of fever

• tachycardia

• acidosis

• dehydration

• 44-46 C (FATAL)

acidosis

an excessively acidic condition of the body fluids and tissues

antimicrobial substances

• complement system

• interferons

• iron-binding proteins

• antimicrobial peptides

complement system

defensive system consisting of over 30 proteins produced by liver and found

circulating in blood serum and within tissues throughout the body

complement system is activated by

• antigen-antibody reaction

• Proteins C3, B, D, P and a pathogen

protein C3b causes

opsonization

proteins C3a and C5a cause

inflammation

C5b + C6 + C7 + C8 + C9 cause

cell lysis

opsonization or immune adherence

enhanced phagocytosis

membrane attack complex

cytolysis

ways bacteria can evade complement system

• capsules prevent C activation

• Surface lipid-carbohydrates prevent membrane attack complex (MAC) formation

• Enzymatic digestion of C5a

interferons (IFNs) IFN-a and IFN-b

Cause cells to produce antiviral proteins that inhibit viral replication

gamma IFN

Causes neutrophils and macrophages to phagocytize bacteria

innate immunity

• transferrins

• antimicrobial peptides

transferrins purpose

bind serum iron

antimicrobial peptides purpose

lyse bacterial cells