Temperature regulation

Question 1

What happens if temperature is too low?

Answer 1

Slow metabolism
Inadequate oxygen supply
Freezing of cells

Question 2

What happens if temperature is too high?

Answer 2

Proteins denature
Inadequate oxygen supply
Membrane structure alterations

Question 3

How is heat exchanged and what percentage of loss does each process make up?

Answer 3

Radiation = 60% (without contact), conduction = 3% (with contact), convection = 15% and evaporation = 22%

Question 4

How do exotherms regulate temperature?

Answer 4

Heat is derived from the environment. Are conformers, temperature fluctuates with the environment.

Question 5

How do endotherms regulate temperature?

Answer 5

Heat is derived from metabolism and temperature is relatively constant. They are regulators

Question 6

How may exotherms regulate temperature?

Answer 6

By changing their behaviour, e.g. sitting In the shade/sun

Question 7

What are the benefits of being an ectotherm?

Answer 7

Metabolic rate is 5 times slower than endotherms, so they use less energy, meaning they need less food and water. A large proportion of the diet can be devoted to reproduction, and are good colonisers of arid environments

Question 8

What are the costs of being an ectotherm?

Answer 8

No nocturnal environmental niches can be filled, unless in the tropics
Cannot sustain high activity bursts at of risk of O2 debt
Anaerobic respiration leads to lactate accumulation which causes rapid fatigue
Susceptible to predation by endoderms

Question 9

What are the benefits of being an endotherm?

Answer 9

Can sustain high activity bursts
Nocturnal activity in all habitats
Able to exploit cooler environments
Forage widely and migrate over long distances

Question 10

What are the costs of being an endotherm?

Answer 10

Require larger body mass sizes with low SA:V ratio
Metabolic rate is 5x faster than for ectotherms
More energy use requires more food and water intake
Cannot devote a large proportion energy budget to reproduction
Poor colonisers of poor/arid environments

Question 11

What is the thermoneutral zone?

Answer 11

Temperature range where animal doesn’t need to expend energy to maintain temperature. Upper and lower limit is set by the hypothalamus

Question 12

What is the hypothalamus?

Answer 12

Part of the forebrain that functions in maintaining homeostasis, especially in coordinating the endocrine and nervous system, secretes hormones into the posterior pituitary gland

Question 13

What is the pituitary gland?

Answer 13

An endocrine gland at the base of the hypothalamus, releases hormones produced by hypothalamus

Question 14

What happens in vasoconstriction?

Answer 14

Diameter of superficial blood vessels decrease, blood flow to skin consequently decreases and skin cools. Less heat is lost to the environment by radiation, conduction and convection, heat is trapped in body core

Question 15

What happens in vasodilation?

Answer 15

Diameter of superficial blood vessels increase, blood flow to the skin increases. Skin heat increases and more heat is lost to the environment through radiation, conduction and convection

Question 16

Describe shivering mechanism

Answer 16

Rapid contractions of skeletal muscles - consumes ATP, which generates heat. Heat production is increased by. 500%.

Question 17

How does adrenaline act in the body?

Answer 17

Released form adrenal medulla and stimulates flight or fight, increases heart rate

Question 18

How does thyroxine act in the body?

Answer 18

Released from the thyroid, and increases basal metabolic rate

Question 19

How does insulation conserve heat?

Answer 19

Cells are rich in mitochondria, which breakdown fuel into heat. Has a rich blood supply specialised for rapid heat production. Found in newborn mammals, hibernating mammals and the necks of human adults. Cells have no intracellular organelles and little blood supply

Question 20

What are counter current heat exchangers?

Answer 20

Hot artery flows by colder veins and exchanges heat, so cold blood doesn’t return to the heart. Flow of adjacent fluids in opposite directions that maximise transfer of heat (or solutes)

Question 21

What is brown fat?

Answer 21

Adipose tissue. specialised for rapid heat production

Question 22

What is blubber?

Answer 22

Thick layer of vascularised adipose tissue under the skin of marine mammals. Low thermal conductivity of skin, with low metabolic activity

Question 23

How are fur/feathers used to insulate?

Answer 23

Reduces convection by trapping a layer of warm air close to the skin surface. Effect is lost if air is replaced by water

Question 24

How does perspiration function in heat loss?

Answer 24

Glands in skin secrete sweat into the surface to increase heat loss by evaporation - Water has greater capacity for absorbing heat than air, absorbs heat when it evaporates

Question 25

How does panting function in heat loss?

Answer 25

Evaporation of moisture from mouth and tongue, and exchanges hot air in the lungs with cooler external air

Question 26

What is the Gular flutter?

Answer 26

Birds rapidly flap membrane in the throat to increase evaporation

Question 27

What is urohidrosis?

Answer 27

Birds defecate on legs for evaporative cooling

Question 28

What happens if metabolic heat production cannot account for heat loss?

Answer 28

Hypothermia

Question 29

What happens if evaporative cooling cannot account for heat gain?

Answer 29

Hyperthermia

Question 30

What is the roe of thermoreceptors in the hypothalamus?

Answer 30

Detects blood temp

Question 31

What is the role of thermorecptors in the skin?

Answer 31

Detect external temp