Thermoregulation

Question 1

What is a homeotherm?

Answer 1

An organism which maintains a constant internal temperature regardless of the external influence

Question 2

What is a poikilotherm?

Answer 2

An organism whose internal temperature changes with ambient temperature

Question 3

What is heat a result of?

Answer 3

A by-product of metabolism

Question 4

How do homeothermic animals regulate a constant internal temperature?

Answer 4

Regulate rate of heat produced and heat loss to control the overall body temperature

Question 5

There are limits to thermoregulatory mechanisms and two issues can arise if the temperature is too high or too low, what are these?

Answer 5

Too high - hyperthermia

Too low - hypothermia

Question 6

What is hypothermia?

Answer 6

Abnormally low body temperature

Question 7

What is hyperthermia?

Answer 7

Dangerously high body temperature

Question 8

Why is thermoregulation important?

Answer 8

For cellular function - homeostasis ensures optimal temperature for cellular metabolism

Question 9

What is the normal body temperature?

Answer 9

37 degrees

Question 10

List five factors which would affect the normal body temperature

Answer 10

1. diurnal variation
2. menstrual cycle
3. exercise
4. age
5. ambient temperature

Question 11

What is diurnal variation?

Answer 11

the variation between a high temperature and a low temperature that occurs during the same day

Question 12

At what temperatures would you die? Max and min please lol

Answer 12

max would be 43ish and min would be 26 degrees

Question 13

What occurs when the the body overheats?

Answer 13

Nerve malfunction and protein denaturation

Question 14

At what temperature would there be body convulsions?

Answer 14

41 degrees

Question 15

What temperature is the upper limit compatible with life?

Answer 15

43.3 degrees

Question 16

What occurs when the body cools?

Answer 16

The metabolic activity decreases but the tissues may withstand transient substantial cooling

Question 17

Overheating is considered more serious than cooling, true or false?

Answer 17

True

Question 18

The body temperature differs between which two regions?

Answer 18

The core body temperature differs from the shell temperature

Question 19

What is included in the core body temperature? Which regions?

Answer 19

The CNS, abdominal and thoracic cavities

Question 20

How would you describe the temperature regulation and general temperature of the core regions?

Answer 20

Precisely regulated and the highest temperature between the to, roughly 37.8 degrees

Question 21

What regions are included within the shell temperature|?

Answer 21

Skin and subcutaneous fat, and basically the outer parts lol

Question 22

What temperature range does the shell temperature fluctuate between?

Answer 22

Around 20 degrees to 40 degrees

Question 23

How is heat exchanged between the core and the shell regions of the body?

Answer 23

By blood homie x

Question 24

What is required for the heat in the body to be balanced, this is basically a btec question.

Answer 24

The heat input must equal the heat output

Question 25

Where may you gain heat from?

Answer 25

Internal heat production and the external environment

Question 26

Where may you lose heat to?

Answer 26

To the environment

Question 27

If the heat input and heat output is not equal, we have a disruption of the

Answer 27

HEAT BALANCE (btec question once again, sorry)

Question 28

What are the four mechanisms of heat transfer?

Answer 28

Radiation, conduction, convection and evaporation

Question 29

Describe what radiation is?

Answer 29

The emission of heat energy from the surface of a warm body via em waves

Question 30

If the skin temperature is greater than the environmental temperature what occurs via radiation?

Answer 30

Heat is lost to the surroundings - so it cools the bod down a bit basically

Question 31

Describe what the mechanism of heat transfer conduction involves?

Answer 31

The transfer of heat between two objects in direct contact

Question 32

What two factors does heat transfer via conduction depend on?

Answer 32

On the temperature difference and the conductivity of the objects

Question 33

Describe the process of convection

Answer 33

It is the transfer of heat by air/ water currents. The heat is conducted to the air immediately next to the skin

Question 34

What is a convection current?

Answer 34

Warm air rises and is replaced by cool air,

Question 35

On what kind of day would you expect more heat loss by convection currents?

Answer 35

On a windy day

Question 36

What is evaporation?

Answer 36

The conversion of water from a liquid form to a gas form

Question 37

Why does evaporation cool the body down?

Answer 37

Because it requires thermal energy which is absorbed from the skin which obvs cools down the body

Question 38

How would you describe the process of insensible water loss by evaporation?

Answer 38

It is a continuous (passive) process

Question 39

How can water be lost 'insensibly', under the category of insensible loss?

Answer 39

Respiratory airways (air is humidified) and the skin

Question 40

What nervous system regulates sensible loss?

Answer 40

The sympathetic nervous system

Question 41

Sensible water loss includes what process by which glands?

Answer 41

Sweating by eccrine sweat glands

Question 42

How much water would you normally expect to lose per day?

Answer 42

100 ml a day

Question 43

How much water would you expect to lose on a hot day?

Answer 43

1.5 litres a day

Question 44

How much water would you expect to lose with vigorous exercise?

Answer 44

4 litres per day

Question 45

What is the humidity?

Answer 45

The amount of water vapour present in the air

Question 46

If the relative humidity is high, this means the air is almost fully saturated with h2o, how would this affect the body in terms of thermoregulation?

Answer 46

There would be limited evaporative heat loss

Question 47

Which two ways does the body get heat input internally?

Answer 47

Oxidation of fuel and utilisation of ATP

Question 48

How efficient is oxidation of fuel, and how efficient is the utilisation of ATP?

Answer 48

50% efficiency for the oxidation of fuel and 25% efficiency for the utilisation of ATP

Question 49

How does the body get heat input externally?

Answer 49

From the environment

Question 50

How does the body lose heat?

Answer 50

Externally, by radiation, conduction and convection

Question 51

How much of heat is lost by radiation?

Answer 51

50%

Question 52

How much of heat is lost by conduction?

Answer 52

A small amount

Question 53

How much heat is lost by convection?

Answer 53

A significant amount

Question 54

What is the only mechanism of heat loss on a hot day?

Answer 54

By evaporation depending on relative humidity

Question 55

What is the thermoregulatory integrating centre?

Answer 55

The hypothalamus

Question 56

What is the posterior region of the hypothalamus activated by?

Answer 56

By the cold

Question 57

What is the anterior region of the hypothalamus activated by?

Answer 57

By the heat

Question 58

How do thermoreceptors work?

Answer 58

They get afferent input to the hypothalamus

Question 59

There are central and peripheral thermoreceptors, what are they?

Answer 59

The central would be the brain, spinal cord and internal organs, the peripheral would be the skin

Question 60

What is the aim of the skin vasomotor responses?

Answer 60

To alter the temperature gradient between the skin and the environment

Question 61

The radius of blood vessels determines what?

Answer 61

The blood flow obviously

Question 62

Blood flow can very between which ranges per minute?

Answer 62

400-2500ml/min

Question 63

Which sub division of the sympathetic nervous system is involved in vasoconstriction and vasodilation?

Answer 63

The sympathetic nervous system

Question 64

Describe vasoconstriction

Answer 64

There is a smaller diameter, greater resistance, lower blood flow, lower skin temp, lower conductive and radiative heat loss, conserves heat

Question 65

Describe vasodilation

Answer 65

Greater diameter, lower resistance, greater blood flow, higher skin temp, higher conductive and radiative heat loss

Question 66

What does shivering do when you are cold as a method of heat conservation and heat producing?

Answer 66

Shivering is heat producing as obvs the skeletal muscles move

Question 67

What are the three effectors involved in thermoregulation?

Answer 67

1. Peripheral blood vessels 2. Sweat glands – eccrine 3. Skeletal muscles

Question 68

How does the effector the peripheral blood vessels respond

Answer 68

Peripheral blood vessels • vasoconstriction / vasodilation alters BF to skin • >> control conductive & radiative heat loss

Question 69

How does the effector, the sweat glands respond

Answer 69

Sweat glands - eccrine • control evaporative heat loss • sweat production (sympathetic control)

Question 70

How does the effector the skeletal muscles respond?

Answer 70

Shivering - increase in muscle tone • rapid involuntary rhythmic contractions (10-20/sec) • ALL energy liberated is converted to heat • 2-5 fold increase in heat within secs/mins

Question 71

Changes in skin temperature are monitored by what?

Answer 71

By peripheral thermoreceptors in the skin

Question 72

Changes in the core temperature is monitored by what?

Answer 72

By central thermoreceptors in the hypothalamus, abdominal organs,

Question 73

Define fever

Answer 73

The elevation of blood temperature as a result of infection/inflammation

Question 74

What triggers fever?

Answer 74

Infection or inflammation

Question 75

What happens to white blood cells when one has fever?

Answer 75

They proliferate and secrete chemical substances

Question 76

What are the chemical substances that while blood cells release when one has fever?

Answer 76

Endogenous pyrogens - fever inducers

Question 77

What do endogenous pyrogens stimulate the release of?

Answer 77

Of prostaglandins

Question 78

What effect do prostaglandins have on the body?

Answer 78

They increase the hypothalamic set point

Question 79

What is the effect of the increasing of the set temperature by the hypothalamus?

Answer 79

The body thinks its too cold, involuntary and voluntary heat production mechanisms begin

Question 80

What is a common symptom of the onset of fever?

Answer 80

Feeling cold

Question 81

Fever is an intentional response of the body and not a failure of the thermoregulatory system, why?

Answer 81

A higher temperature augments the immune response

Question 82

What is the most common cause of hypothermia?

Answer 82

Exercise

Question 83

Explain how exercise induced hypothermia takes place

Answer 83

As a physical consequence of the tremendous heat load generated by exercising muscles, body temperature begins to rise during the initial stage, stabilises, and then maintained at a higher level during exercise several degrees above resting set point

Question 84

Explain how hyperthermia can occur pathologically?

Answer 84

Due to dysfunction of the thyroid gland, medulla or brain lesions

Question 85

How can hyperthyroidism caused hyperthermia?

Answer 85

An increase of thyroid hormone, an increased basal metabolic rate, increased heat production

Question 86

How does aspirin act to break a fever?

Answer 86

Aspirin reduces a fever by inhibiting the synthesis of prostaglandins

Question 87

Why does aspirin not lower the temperature in a non febrile individual?

Answer 87

In the absence of endogenous pyrogen, prostaglandins are not present in the hypothalamus in appreciable quanitites