5.3 Homeostasis and thermoregulation

Question 1

what is homeostasis?

Answer 1

process of maintaining our internal environment within narrow limits. Dynamic equilibrium

Question 2

why is homeostasis important?

Answer 2

chemical reactions must take place within the body and they can only take place if conditions are right

Question 3

what conditions must be maintained?

Answer 3

chemicals
pH
temperature
water balance

Question 4

what systems do organisms use to monitor and respond to changes from the steady state of the body?

Answer 4

chemical and electrical systems

Question 5

what do chemoreceptors detect?

Answer 5

chemical changes

Question 6

what do baroreceptors detect?

Answer 6

pressure changes

Question 7

what do thermoreceptors detect?

Answer 7

temperature changes

Question 8

what is an effector of chemoreceptors and why?

Answer 8

muscles

push blood containing CO2 to lungs getting rid of carbonic acid and restoring pH balance

Question 9

what is the baroreceptors effector and why?

Answer 9

SAN

initiates decrease when a rise is detected by baroreceptors

Question 10

receptors are important in homeostasis in detecting what?

Answer 10

changes to internal and external environment

Question 11

what is convection?

Answer 11

transfer of heat in a gas or liquid by upward movement of warm air or liquid

Question 12

what is conduction?

Answer 12

transfer of heat from a warmer solid object to a cooler one in direct contact

Question 13

what is radiation?

Answer 13

transfer of heat as infrared rays

Question 14

what is evaporation?

Answer 14

when liquid changes to a gas and has a cooling effect

Question 15

what do ectotherms use to warm their bodies and core temperature?

Answer 15

environment

Question 16

what organisms do ectotherms include?

Answer 16

invertebrates
fish
amphibians
reptiles

Question 17

many ectotherms in water don’t need to thermoregulate, why?

Answer 17

high heat capacity of water means the temp of their environment doesn’t fluctuate much

Question 18

why do ectotherms need to warm to a specific temperature?

Answer 18

need to warm to a temp when metabolic reactions happen fast enough to be active e.g. to catch prey

Question 19

one behavioural adaptation of ectotherms is to lay in the sun and orientate their body why?

Answer 19

increase sa exposed to sun to take in as much heat as possible

Question 20

give an example of an ectotherm displaying the behavioural adaptation of laying in the sun and orientating their body:

Answer 20

lizards

bask in the sun for long periods in other to get warm enough to move fast and hunt

Question 21

how do insects show the ectotherms behavioural adaptation of using the sun to warm?

Answer 21

spread wings to increase sa to take in heat in order to get warm enough to fly

Question 22

(behavioural) some ectotherms press their bodies against warm ground, why?

Answer 22

heat from conduction

Question 23

(behavioural) moths and butterfly’s do what in order to warm their muscles to take flight?

Answer 23

vibrate their wings

Question 24

what behavioural adaptations do ectotherms have to decrease core temp?

Answer 24

shelter in shade
dig burrows 
press against cold rocks
orientate so minimum area is exposed to sun
minimise movement
go into water

Question 25

what is a physiological adaptation some ectotherms have regarding their colour?

Answer 25

dark colours absorb more radiation

so lizards in colder climates tend to be darker to gain more heat

Question 26

(physiological) some ectotherms alter their heart rate in order to do what?

Answer 26

increase or decrease metabolic rate in order to regulate temperature

Question 27

(endotherms) the hypothalamus detects temperature changes in what?

Answer 27

the blood

Question 28

(endotherms) temperature receptors in the skin detect changes in what?

Answer 28

surface temperature

Question 29

what do endotherms rely upon to warm their bodies and maintain a stable temperature?

Answer 29

metabolic processes

Question 30

what behavioural adaptations do endotherms share with ectotherms?

Answer 30

bask in the sun
press themselves against warm surfaces (conduction)
dig burrows
go in water to cool
hibernation

Question 31

what additional behavioural adaptations do humans (endotherms) have to stay warm?

Answer 31

wear clothes
build homes for shelter
heating systems to warm their house

Question 32

what are the three physiological cooling responses endotherms use?

Answer 32

vasodilation
increased sweating
reducing insulating effect of hair

Question 33

how do endotherms use vasodilation? (cooling)

Answer 33

arterioles at skin surface dilate in warm temperatures
shunt vessels constrict forcing blood through capillary networks near skins surface, causing skin to cool due to increase radiation

Question 34

how do endotherms use sweating? (cooling)

Answer 34

increased temp sweat spreads across skin as it evaporates heat is lost cooling the blood near the surface