Test 3: Regulation of Body Temperature

Question 1

Is temperature uniform throughout the body? Explain the ‘parts’ of the body. What are their temperatures?

Answer 1

NO!
1) Inner Core:
- deep body temperature
- measured in the rectum
mammals: 36.5 - 39.5 * C
birds: 38 - 42 * C

2) Outer Shell

Question 2

What fluctuations in temperature are normal for animals over a 24h period?

Answer 2

0.5-1.0 * C

Question 3

What is the regular mammal core temperature?

Answer 3

between 36.5 * C and 39.5 * C

Question 4

What is the regular bird core temperature?

Answer 4

between 38 * C and 42 * C

Question 5

Explain the distrubution of temperatures in an organism under warm and cold environmental conditions.

Answer 5

Warm conditions:
- the core body temperature extends into the limbs and close to the skin surface of the animal.

Cold conditions:
- vasoconstriction in the peripheral blood vessels results in a gradient of temperatures between the core and the extremities.
- The core temperature is maintained only in the abdomen, thorax, and brain of the animal.
- The more peripheral tissues are allowed to cool considerably.

Question 6

What influences body temperature?

Answer 6

metabolic rate

Question 7

Explain the circumstances in which organisms may have hyperthermia. What is hyperthermia?

Answer 7

Hyperthermia- elevated body temperatures
- during excercise
- pregnant, lactating, rapidly growing animals
- thyroid hormone

Question 8

What affects body temperature restraint?

Answer 8

• internal insulating layers (eg. white and brown adipose)
• external insulating layers (eg. hair and feathers)

Question 9

What must be achieved in order for an organism to maintain a stable body temperature?

Answer 9

• a stable body temperature:
• heat inpute = heat output

Question 10

Explain the metabolic rates in endothermic and ectothermic animals. What are they?

Answer 10

Ectotherms:
- low metabolic rate
- cannot regulate body temperature
- internal temperature = environment temperature
- cold-blooded
- all animals except of birds and mammals

Endotherms:
- high metabolic rate
- produce internal heat
- heat produced by the metabolism of food
- warm-blooded
- birds and mammals

Question 11

How do endothermic animals regulate their body temperature?

Answer 11

gain metabolic heat:
- cellular respiration
- muscular contraction

regulate:
- behaviour (ie. finding shade, panting, reduced activity)

Question 12

Explain temperature variation over time. What happens in cold-blooded animals? Warm blooded?

Answer 12

Cold-blooded:
- body temperature fluctuates with the external environment
- poikilotherms (“fluctuating heat”)

Warm-blooded:
- body temperature is regulated by internal mechanisms - more stable
- homeotherms (“same heat”)

Question 13

What happens to all energy of an animal if it is:
- not growing
- not preforming physical work
- not pregnant
- not lactating
?

Answer 13

All energy released from nutrients is converted to heat.

Question 14

How much faster can heat production become during muscle activity?

Answer 14

20 times higher than at rest

Question 15

What is an example of involutary muscle contraction created to increase heat production?

Answer 15

shivering

Question 16

How is heat loss regulated? By what? What acts as thermal insulators?

Answer 16

by controlling blood flow to the skin
- by the sympathetic nervous system

Thermal Insulators:
- skin
- fur
- feathers
- subcutaneous tissues (poor conductor of heat)

Question 17

What do aquatic birds use to maintain a water-repellent plumage?

Answer 17

• fatty secretion
• from the uropygial gland

Question 18

What do whales, seals and polar bears use to limit heat loss and remain in freezing water for long periods (without developing hypothermia)?

Answer 18

insulating layer of fat:
blubber
- in their subcutaneous tissue

Question 19

Explain the correlation of heat production to body mass.

Answer 19

As heat production increases, body mass increases parallely.

Question 20

By what 4 processes is heat transported?

Answer 20

• radiation
• conduction
• convection
• evaporation and condensation

Question 21

What do all processes of heat transportation follow?

Answer 21

a temperature gradient:
warmer –> colder

Question 22

Explain the “radiation” process of heat transfer.

Answer 22

electromagnetic radiation is:
- partially absorbed
- partially reflected

Absorbed Radiation:
- converted to heat
- increases body temperature of object

Simoultaneously:
- radiation is emmited from the object
- reduction of heat energy

Question 23

What plays an important role in the absorption of visible light?

Answer 23

skin colour:
black- absorbs more solar radiation (90%)
white- (50% absorbed)

Question 24

Explain the “conduction” process of heat transfer.

Answer 24

Conduction:
- heat transfer between objects in direct contact
- heat loss: body in contact with cooler surface

Question 25

Explain the "convection" process of heat transfer.

Answer 25

Convection: - transfer of heat by moving air or water - heat loss: body temperature is higher than air temperature Insulation: - reduces convective heat loss - ie. fur, feathers

Question 26

Explain the "evaporation" process of heat transfer. State examples of this process.

Answer 26

Evaporation: - water --> gas / water vapour - cools animal - eg. sweating, panting, wetting of body surface

Question 27

Explain the 4 processes using a dog in a pool.

Answer 27

- heat is released by **evaporating** through panting, - heat from the sun **radiates** into the body, and heat from the body radiates into the air, - the wind cools the body by **convection**, - heat from the body is transferred into cooler water by **conduction**.

Question 28

What is the 'optimal temperature zone' called? What is it in other words?

Answer 28

the **thermoneutral zone**: - most energetically efficient zone

Question 29

What is hyperthermia?

Answer 29

When heat production exceeds heat loss. - body temperature rises above normal ranges

Question 30

What is hypothermia?

Answer 30

When the increase in body temperature is not sufficient to compensate for the heat lost. - body temperature deops below normal ranges

Question 31

What is a fever? When does it occur?

Answer 31

- raise in body temperature - occurs during infections and injuries

Question 32

State examples of predisposing factors that increase an animal's risk for hypothermia.

Answer 32

- very young - very old - low body fat - inadequate hair coat - recent surgeries (prolongued anesthesia) - small breeds - prolongued exposure to cold temperatures - wet fur and skin

Question 33

State examples of predisposing factors that increase an animal's risk for hyperthermia.

Answer 33

- increased ambient temperature - humidity - excessive muscle exertion - excessive metabolic activity - physical structure - dehydration - trauma - restraint

Question 34

State clinical signs of hyperthermia.

Answer 34

- increased heart rate - increased respiration - open mouth breathing - increased sweat and saliva - weakened pulse - restlessness - slow responsiveness - uncoordination - convulsions - collapse - death

Question 35

State clinical signs of hypothermia.

Answer 35

- shivering - slow shallow breathing - weakness - lethargy (lack of energy and enthusiasm) - low blood pressure - muscle stiffness - dilated pupils - hard to fins heartbeat - coma

Question 36

How is body temperature regulated?

Answer 36

by **reflexes**: - *sensory* components - the *thermoregulatory center* - *motor* components by **behavioural patters**: - ambient temperature increases: shade seeking, wind seeking, increased hairless skin parts exposure, etc. - ambient temperature decreases: hurdling together, curling up, insulating nesting material, seek shelter, etc.

Question 37

State examples of sensory inputs of body temperature regulation.

Answer 37

warmth and cold sensors in: - skin - internal organs - hypothalamus

Question 38

State examples of motor outputs of body temperature regulation.

Answer 38

heat stress: - behaviour - increased blood flow to skin - sweating - panting cold stress: - behaviour - reduced blood flow to skin - shivering - activation of brown adipose tissue - hormone secretion

Question 39

Explain vasoconstriction and vasodilation in terms of body temperature regulation.

Answer 39

Vasodilation: - increased blood flow to skin surface - increased heat loss Vasoconstriction: - decreased blood flow to skin surface - decreased heat loss