week 7 - personal

what is homeostasis

maintaining a stable internal environment despite external changes

is homeostasis static or dynamic

dynamic equilibrium (constantly adjusting)

what is allostasis

maintaining stability through change (adjusting set points based on demand)

key difference between homeostasis and allostasis

homeostasis → fixed set point

allostasis → shifting set point

example of allostasis

heart rate increasing during exercise

what is negative feedback

a response that reverses a deviation from a set point

steps of negative feedback

1. stimulus

2. sensor

3. control center

4. effector

5. response restores balance

what is positive feedback

amplifies change until a process is completed

examples of positive feedback

childbirth contractions

what is thermoregulation

maintaining body temp within a tolerable range

why is temperature important biologically

affects enzymes, metabolism, membranes, oxygen binding

what is an endotherm

generates internal heat (mammals, birds)

what is an ectotherm

relies on environmental heat (fish, reptiles)

homeotherm vs poikilotherm

homeotherm → constant temp

poikilotherm → variable temp

in what direction does heat move

from warm → cold

four mechanisms of heat exchange

• radiation

• conduction

• convection

• evaporation

what is vasolidation

blood vessels widen → heat loss

what is vasoconstriction

blood vessels narrow → heat conserved

role of hypothalamus

bodys thermostat (control center)

how does hypothalamus respond to heat

sweating, vasodilation

how does it respond to cold

shivering, vasoconstriction

what is brown adipose tissue

heat-producing fat tissue

how does it generate heat

thermogenin allows heat production without ATP

what is acclimation

short-term physiological adjustment

what is adaptation

genetic change over generations

what is a regulator

maintains internal conditions despite environment

example of regulator

river otter maintaining body temp

what is a conformer

internal conditions change with environment

example of conformer

fish body temperature matching water

what are thermal adaptations

evolved traits reducing need for constant regulation

example of thermal adaptations

• blubber/fat

• hibernation

• migration

• brown fat

why do hummingbirds lower body temp at night

to conserve energy due to high metabolism

what is countercurrent heat exchange

heat transfer between adjacent arteries and veins

why is countercurrent heat exchange useful

reduces heat loss in extremities

how do ectotherms regulate temperature

behavioral changes (move to warmer/cooler areas)

what is behavioral fever

moving to warmer areas when infected

why do swordfish have eye/brain heaters

improve vision in cold water

why is this eye heaters necessary

cold slows retinal processing → harder to track prey

what are the 3 stages of homeostasis control

• input (sensors detect change)

• integration (CNS processes info)

• output (response restores balance)

why is negative feedback essential

prevents systems from becoming unstable

why is positive feedback rare

it destabilizes systems

why are endotherms more energetically expensive

they must generate their own heat

why are ectotherms more energy efficient

use environmental heat