homeostasis

Question 1

what is the thermoneutral zone?

Answer 1

ambient temperature, no adjustments are needed and no energy is required to adjust body temp

Question 2

when is energy required to change body temp?

Answer 2

during critical temperatures where it is hot or cold and the body needs to dissipate or produce heat

Question 3

what is hyperthermia and how does it affect the body?

Answer 3

heat stress, cells can’t function due to the denaturation of enzymes and proteins (42°), can be fatal

Question 4

what is hypothermia and how does it affect the body?

Answer 4

cold stress, slows down blood circulation and respiration which may fail and cause death

Question 5

which is more survivable for mammals: hypothermia or hyperthermia, and why?

Answer 5

hypothermia is more survivable because proteins don’t denature, however they do during hyperthermia; the body may also reach a point where it generates more heat than it dissipates due to the heat produced by energy spent trying to rid the heat; cells can also be revived after being frozen but the cardiovascular system will be slowed

Question 6

are mammals and birds endothermic or exothermic?

Answer 6

endothermic, heat comes from body production and is not energy efficient

Question 7

what processes produce body heat?

Answer 7

metabolism, growth and production, exercise

Question 8

why are broilers borderline hyperthermic?

Answer 8

they are bred to grow fast which causes lots of energy and heat production

Question 9

what are the four processes used to transport heat?

Answer 9

• radiation
• conduction
• convection
• evaporation/condensation

Question 10

what is radiation?

Answer 10

energy/heat transfer via electromagnetic spectrum

Question 11

what is conduction?

Answer 11

energy/heat transfer via direct contact, travels from high to low temps

Question 12

what is convection?

Answer 12

energy/heat transfer by air or water

Question 13

what is evaporation/condensation?

Answer 13

breakdown of water molecules using heat energy

Question 14

how do animals produce extra heat?

Answer 14

• muscle activity by shivering
• non shivering thermogenesis

Question 15

how does shivering work?

Answer 15

antagonistic muscles contracting simultaneously, all energy goes to heat production so it is not exercise

Question 16

how does non shivering thermogenesis work?

Answer 16

sympathetic ns secretes catecholamines/adrenalin which increase metabolism especially from brown fat, also a prolonged endocrine response which releases thyroid hormones to increase metabolism

Question 17

how do animals lose extra heat?

Answer 17

• vasodilation for heat to move to the skin via blood; then radiation, conduction, or convection
• evaporation; passive, sweating, panting, bathing

Question 18

how does panting rid heat?

Answer 18

dry air is brought in, charged with humidity in the nasal passages (heat exchange organ/turbinate bones), and hot vapour is brought out

Question 19

what are the system components of thermoregulation?

Answer 19

• thermoreceptors: nerve cells
• integration centre: hypothalamus
• effectors: neurons, sympathetic NS, hormones
• voluntary component: behavioural change

Question 20

how does the hypothalamus know when to start thermoregulating?

Answer 20

it takes information from the sensors/nerve cells and compares it to internal reference set points

Question 21

what is homeostasis?

Answer 21

maintenance of a constant environment through automatic coordinated organ responses

Question 22

what is a homeotherm?

Answer 22

an animal with the ability to generate and dissipate their own heat (mammals and birds)

Question 23

do lactating or non lactating cows produce more heat and why?

Answer 23

lactating; heat is generated by milk production

Question 24

what is BMR?

Answer 24

basal metabolic rate; amount of energy generated just to be alive

Question 25

what happens to the metabolic rate as the temperature increases or decreases?

Answer 25

it increases to produce heat or try to rid the heat

Question 26

what are the system components involved in a response to heat?

Answer 26

receptors: thermoreceptors in the skin, core (vessels, organs) transfer info via warm sensory fibres integration: hypothalamus activates heat loss center (anterior) effectors: sympathetic vasoconstriction fibres slow down, sympathetic activity increase for evaporative heat loss (sweating and panting), reduce physical activity behaviour: seeking shade

Question 27

which animals are good at handling heat and which animals are bad?

Answer 27

cattle, sheep, birds (air sac in body cavity for ventilation) are very good, pigs are very bad due to little sweat and small mouth for panting

Question 28

what are the system components involved in a response to cold?

Answer 28

receptors: skin, core transfer info through cold sensory fibres (more than warm fibres) hypothalamus: activates heat producing centre (posterior) effectors: sympathetic vasoconstriction fibres fire, pili muscles contract, shivering from somatic motor system, increase in sympathetic and hormonal activity, increase in metabolism (esp. in brown fat)

Question 29

what are ways animals have adapted to heat?

Answer 29

- sweating, increase in aldosterone stimulates reabsorption of sodium and chlorine from sweat glands - shedding

Question 30

what are ways animals have adapted to cold?

Answer 30

- change in fur coat, increase of insulation (subcut. fat) - hibernation, decreases MR, body temp.

Question 31

what is the pathology of a fever?

Answer 31

- resets hypothalamus to a higher level - response is equivalent to a decrease in temp. - caused by pyrogens/cytokines that fight infection/inflammation

Question 32

what is the pathology of hyperthermia?

Answer 32

- heat production exceeds heat loss - convulsions, nausea, loss of consciousness, death

Question 33

what is the pathology of hypothermia?

Answer 33

- heat loss exceeds heat production - slow NS, muscular failure esp. in cardiac and pulmonary, death