7: Feedback control of body temperature Flashcards

1
Q

Temperature is an example of a variable which must be maintained within narrow limits in the human body. This process is called _______.

A

Homeostasis

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2
Q

What is the definition of core body temperature?

A

The temperature of structures deep within the body

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3
Q

What is the average core temperature of a human (to 3 significant figures)?

A

37.8 degrees Celsius

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4
Q

Why isn’t the skin a good site for monitoring body temperature?

A

The temperature of the skin varies widely

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5
Q

The core body temperature is kept ____ despite changes in the environment.

A

constant

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6
Q

What is nomrothermia?

A

The normal core body temperature

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7
Q

What is ear drum temperature also known as?

A

Tympanic temperature

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8
Q

Name three areas where body temperature can be taken.

A

Ear drum, rectum, orally

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9
Q

What is diurnal variation in body temperature?

A

Changes in body temperature during the day

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10
Q

To maintain a constant core body temperature, heat ___ and heat ___ must be in balance.

A

gain , loss

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11
Q

What is a source of heat gain within the body?

A

Metabolic heat

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12
Q

What is Basal Metabolic Rate (BMR)?

A

Minimum amount of energy required to sustain vital body functions

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13
Q

Which hormones increase the Basal Metabolic Rate (BMR)?

A

Adrenaline, noradrenaline, thyroxine

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14
Q

Shivering increases ___ production by increasing ___ ___.

A

heat , muscle activity

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15
Q

What is radiation?

A

Emission of heat energy from a surface as electromagnetic waves

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16
Q

The human body both ___ and ___ radiant heat.

A

emits , absorbs

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17
Q

How much of the body’s heat loss occurs through radiation?

A

Around 50%

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18
Q

What is conduction?

A

Transfer of heat between objects in contact

19
Q

In conduction, heat moves from the ___ to ___ object.

A

warmer , cooler

20
Q

What is convection?

A

Transfer of heat energy away from the body by air or water currents

21
Q

Warm air ___, cool air ___.

A

rises, falls

22
Q

Convection and ____ often work together to dissipate heat from the body.

A

conduction

23
Q

What is evaporation?

A

Conversion of water into vapour using energy

24
Q

Where does evaporation occur in the body?

A

The skin surface, lining of the respiratory tract

25
Q

Sweating is an ___ form of evaporative heat loss.

A

active

26
Q

Sweating is controlled by the _____ nervous system.

A

sympathetic

27
Q

What kind of feedback control system regulates core body temperature?

A

Negative feedback

28
Q

What is the temperature control centre called?

A

The hypothalamus

29
Q

The posterior hypothalamic centre is activated by ___.

A

cold

30
Q

The anterior hypothalamic centre is activated by ___.

A

warmth

31
Q

What do skin arterioles do in response to cold?

A

Vasoconstrict

32
Q

What does vasoconstriction result in?

A

Decreased heat loss / heat conservation

33
Q

What do skeletal muscles do in response to cold?

A

Increase their muscle tone Shiver

34
Q

What do skin arterioles do in response to warmth?

A

Vasodilate

35
Q

How does vasodilation increase heat loss?

A

Increases blood flow to the skin, increased radiation/convection/conduction

36
Q

Macrophages release chemicals in response to infection or inflammation. What do these chemicals act as?

A

Endogenous pyrogens

37
Q

Endogenous pyrogens stimulate the release of which chemical in the hypothalamus?

A

Prostaglandins

38
Q

What do prostaglandins to the body’s internal thermostat?

A

Reset it at a higher temperature

39
Q

Is the resetting of the body’s internal thermostat reversible? How?

A

Yes When pyrogen / prostaglandin release stops

40
Q

Fever is a core body temperature between…

A

38 - 40 degrees Celsius

41
Q

What is hyperthermia (definition, not values)?

A

Extreme uncontrolled increase in body temperature

42
Q

What body temperature constitutes hyperthermia?

A

Any body temperature above 40 degrees Celsius

43
Q

What is hypothermia (definition, not values)?

A

Drop in body temperature below that required for metabolism and function

44
Q

What body temperature constitutes hypothermia?

A

Any body temperature below 35 degrees Celsius