PHYSIOLOGY - Thermoregulation

Question 1

What are poikilotherms?

Answer 1

Poikilotherms are ectothermic animals

Question 2

What are homeotherms?

Answer 2

Homeotherms are endothermic animals

Question 3

What is core body temperature?

Answer 3

Core body temperature is the temperature within the cranium, abdominal and thoracic cavities which have a very narrow temperature range

Question 4

What is the shell body temperature?

Answer 4

Shell body temperature is the oral and skin temperature which have a very wide temperature range

Question 5

Which six factors can influence the core body temperature?

Answer 5

Circadian rhythm of core temperature
Seasonal variations
Environmental variations
Exercise
Digestion
Gender

Question 6

Why does the core body temperature fluctuate more in female animals?

Answer 6

Body temperature is influenced by steroids and thus fluctuates with the oestrous cycle in females

Question 7

What are the three methods of heat transfer?

Answer 7

Radiation
Conduction
Evaporation

Question 8

What is radiation of heat?

Answer 8

Radiation is the transfer of heat through electromagnetic waves

Question 9

What is conduction of heat?

Answer 9

Conduction is the transfer of heat through direct contact between objects

Question 10

How does convection affect the conduction of heat?

Answer 10

Convection enhances the conduction of heat as convection is the movement of fluid (like air or water) which will carry heat away from the surface and make the transfer of heat faster and more efficient

Question 11

What is evaporation of heat?

Answer 11

Evaporation is the process by which liquid turns into a gas, taking heat with it

Question 12

Which central nervous system structure regulates thermogenesis?

Answer 12

Preoptic area of the hypothalamus

Question 13

Which two regions receive information from the preoptic area of the hypothalamus to regulate thermogenesis?

Answer 13

Heat promoting centre
Heat losing centre

Question 14

Which three behavioural changes occur to increase body temperature?

Answer 14

Curled up posture
Huddling
Move to warm location

Question 15

Which five physiological mechanisms increase body temperature?

Answer 15

Cutaneous vasoconstriction
Countercurrent exchange mechanisms
Piloerection
Shivering thermogenesis
Non-shivering thermogenesis

Question 16

How does cutaneous vasoconstriction increase body temperature?

Answer 16

Cutaneous vasoconstriction redirects the blood flow to the core organs, increasing the core body temperature

Question 17

Why is periodic vasodilation so important during cutaneous vasoconstriction?

Answer 17

Periodic vasodilation allows for blood flow to the periphery and skin to prevent cell death and necrosis in those areas

Question 18

What are the two potential complications of cutaneous vasoconstriction?

Answer 18

Hypovolaemia
Frostbite

Question 19

How does piloerection increase body temperature?

Answer 19

Piloerection is the contraction of the errector pilli muscles at the base of the hair follicles to trap air, increasing the insulating layer of air around the body to minimise heat loss

Question 20

Which three behavioural changes occur to decrease body temperature?

Answer 20

Open posture
Dispersing
Move to cold location

Question 21

Which two physiological mechanisms decrease body temperature?

Answer 21

Cutaneous vasodilation
Evaporative heat loss

Question 22

How does cutaneous vasodilation decrease body temperature?

Answer 22

Cutaneous vasodilation increases the blood flow to the skin which increases the heat loss from the blood vessels into the environment, increasing heat loss and decreasing body temperature

Question 23

What are the three mechanisms of evaporative heat loss?

Answer 23

Sweating
Panting
Spreading saliva on fur

Question 24

What are the three adaptations seen in animals that live in chronically cold temperatures?

Answer 24

Increased thermal gradient
Increased metabolic rate
Decreased core temperature

Question 25

Which two mechanisms are used to increase thermal gradient?

Answer 25

Burrowing
Development of winter fur

Question 26

Which mechanism is used to decrease core temperature?

Answer 26

Hibernation

Question 27

What are the three adaptations seen in animals that live in chronically hot temperatures?

Answer 27

Decreased thermal gradient
Decreased metabolic rate
Increased core temperature

Question 28

Which mechanism is used to decrease thermal gradient?

Answer 28

Development of a summer coat

Question 29

Which mechanism is used to increase core temperature?

Answer 29

Aestivation

Question 30

What is aestivation?

Answer 30

Aestivation is a state of dormancy in which an animal enters during hot and dry period

Question 31

List two thermoregulatory disorders

Answer 31

Pyrexia
Hypothermia

Question 32

Describe the process resulting in pyrexia

Answer 32

Neutrophils and macrophages secrete endogenous pyrogen IL-1 which acts on the anterior hypothalamus to secrete prostaglandin E (PGE) which raises the set point for body temperature. The body will the shiver and undergo peripheral vasoconstriction to raise the body temperature

Question 33

What happens to the body during stage one of hypothermia (core body temperature between 35-37°C)?

Answer 33

Shivering
Cutaneous vasoconstriction
Rapid and shallow breathing
Nausea
Muscles become less responsive

Question 34

What happens to the body during stage two of hypothermia (core body temperature between 33-35°C)?

Answer 34

Violent shivering
Cutaneous vasoconstriction
Muscles are miscoordinated
Mild confusion
Extremities turn blue

Question 35

What happens to the body during stage three of hypothermia (core body temperature between less than 32°C)?

Answer 35

Shivering stops
Obvious cognitive impairement
Obvious physical inability
Metabolic processes shut down

Question 36

What happens to the body during stage four of hypothermia (core body temperature between less than 30°C)?

Answer 36

Decreased pulse
Increased heart rate
Decreased respiratory rate
Extremities blue and puffy
Incoherent/irrational behaviour
Major organ failure
Death