Temperature regulation

Question 1

How do humans regulate heat

Answer 1

Humans are endotherms and regulate temperature through a negative feedback loop, Mammals lose heat to environment, To maintain a constant (optimal) body temperature, the amount of heat produced must be exactly the same as the amount of heat lost

Question 2

Setpoint

Answer 2

optimal temperature/condition (37.5 degrees)

Question 3

Examples of heat input

Answer 3

cellular respiration, external environment, food

Question 4

Examples of heat output

Answer 4

sweat, urination, vasodilation, breathing

Question 5

Thermoregulation

Answer 5

feedback system which involves the same stimulus, receptors and modulator but different effectors, response and feedback

Question 6

Types of thermoreceptors

Answer 6

Peripheral and central

Question 7

Peripheral thermoreceptors

Answer 7

Found in the skin and some mucous membranes, hot and cold

Question 8

Central thermoreceptors

Answer 8

Found in the hypothalamus, spinal cord and abdominal organs

Question 9

How do we gain and lose heat

Answer 9

Conduction, convection, evaporation, radiation

Question 10

Conduction

Answer 10

Through one solid to another (sitting on the ground, touching cold metal)

Question 11

Convection

Answer 11

Through fluids (liquids and gases) (swimming, steam room, wind)

Question 12

Evaporation

Answer 12

Change of state removes heat (sweat turns into gas and takes heat with it

Question 13

Radiation

Answer 13

Through space (fire, sun, people radiate heat)

Question 14

Decreasing heat loss in cold conditions

Answer 14

Peripheral vasoconstriction of blood vessels, Reduction in sweating, Behaviour (putting on a jumper), Reduction of surface area such as by curling into a ball

Question 15

Increasing heat production in cold conditions

Answer 15

Shivering, Increase in voluntary activity, Increased metabolic rate by increased secretion of Thyroxine and adrenaline

Question 16

Increasing heat loss in hot conditions

Answer 16

Vasodilation of peripheral arterioles in the skin, Sweating, Behaviour (Conscious change in behaviour, E.g Fanning), Increase surface area

Question 17

Decreasing heat production in hot conditions

Answer 17

Decrease voluntary activity, Decrease metabolic rate by decreased thyroxine secretion and adrenaline

Question 18

Body types

Answer 18

Ectomorph, endomorph

Question 19

Ectomorph

Answer 19

African, tall and skinny, have a high/large surface area: volume ratios meaning they lose heat faster

Question 20

Endomorph

Answer 20

Inuit Eskimo, short, plump, have a low/small surface area: volume rations lose heat slower

Question 21

Heat exhaustion

Answer 21

Dehydration (due to sweating) and vasodilation of peripheral arterioles cause low blood pressure (more blood going to arterioles) resulting in inadequate blood to the brain, A person may collapse but temperature remains normal, To assist mainly raise legs to allow blood to go back to the brain

Question 22

Heat stroke

Answer 22

Dehydration (due to sweating), high environmental temperatures and high humidity (lots of moisture in the air meaning sweat doesn’t evaporate) making it difficult to lose body heat (failure of thermoregulation), Heat is then retained as thermoregulation ceases meaning body temperature rises (44-46 degrees) causing failure of organs which can be fatal and enzymes start to denature

Question 23

Hypothermia

Answer 23

If body temperature is below 33 degrees, the metabolic rate is too slow to maintain body temperature (thyroxine and adrenaline can’t help), Heat lost is greater than heat produced meaning temperature continues to fall