B3: inflammation and fever

what sorts of events can cause inflammation?

physical damage: damaged cells → triggered by DAMPs

microbial attack:

• damaged cells

• signals sent from immune cells

• signals from complement activation

what are the 4 symptoms of inflammation?

redness

heat

swelling

pain

what are the 4 steps of inflammation?

vasodilation

blood vessel permeability

phagocyte migration

tissue repair

what happens in vasodilation?

blood vessels expand

increased blood flow to the region (redness and heat)

what does vasodilation provide?

provides greater immune system access → more white blood cells getting carried there

what is blood vessel permeability?

cells weaken their junctions

increases ability of immune cells to move into tissues

what is a side effect of blood vessel permeability?

causes swelling → allows plasma fluid to leak into surrounding tissues

what is a phagocyte migration?

neutrophils and macrophages are attracted to inflammation

use increased permeability of capillaries to move into tissues

who arrives first in phagocyte migration? neutrophils or macrophages?

neutrophils arrive first, being killing pathogens

macrophages arrive later, help with pathogens

• also clear out dead tissue

as phagocytes work, many die from toxic condition

what could you develop from phagocyte migration?

pus: accumulation of dead bacteria and dead phagocytes

• clear sign your body is fighting a microbial infection

what happens in tissue repair?

begins early, but can’t complete until inflammation is reduced

once inflammatory signals are gone, normal cells can begin regenerating

some tissues generate faster than others

which part of inflammation is particularly problematic if it is systemic?

blood vessel permeability

why is blood permeability problematic if it systemic?

septic shock

systemic infection = bacteria is in your blood

• inflammatory response happens everywhere in your body at the same time

• leak fluid everywhere in your body at the same time

• blood pressure drops drastically

what is a fever?

systemic (whole body) response to an infection

what do phagocytes recognize that causes a fever?

bacterial molecules as pyrogens

which organ controls your body’s temperature set point?

hypothalamus

what happens if you get an infection by a virus/bacterium that has a pyrogen in it?

sends a signal to the hypothalamus to increase body temperature

fever convinces the body to heat itself up!

do fevers provide benefits while fighting an infection?

some pathogens grow poorly at increased temperatures

increases rate of metabolism

• may improve tissue repair rates

• may improve production of antimicrobial proteins

when are fevers problematic?

extremely high fevers (>104°)

• tachycardia (increased heart rate)

• nervous system damage

• >107° is potentially lethal