thermoregulation

Question 1

what is an endotherm

Answer 1

an animal that is dependent on or capable of the internal generation of heat

Question 2

what is an ectotherm

Answer 2

an animal that is dependent on external sources of body heat

Question 3

what is a homeotherm

Answer 3

an organism that maintatins its body temperature at a constant level, usually above that of the environment by its metabolic activity

Question 4

what is a poikilotherm

Answer 4

an organism that cannot regulate its body temperature except by behavioural means such as basking or burrowing

Question 5

what are the 4 physical processes of heat exchange

Answer 5

Question 6

how may endotherms respond to the cold

Answer 6

• shivering
• vasconstriction
• no sweating
• increase basal metabolic rate
• hairs stand on end
• increase muscle activity

Question 7

how may endotherms respond to heat

Answer 7

• reduced activity
• decreased basal metabolic rate
• vasodilation
• sweating
• hairs lie flat
• panting

Question 8

where is the thermoregulatory centre located

Answer 8

the hypothalamus

Question 9

what is the thermoneutral zone

Answer 9

The range of ambient temperatures where the body can maintain its core temperature solely through regulating dry heat loss, i.e., skin blood flow. Within the TNZ the basal rate of heat production is equal to the rate of heat loss to the environment.

Question 10

What is the definition of lower and upper critical temperatures?

Answer 10

Lower critical temperature
- theminimum body temperature that can be tolerated by an organism.

Upper critical temperature
- the maximum body temperature that can be tolerated by an organism.

Question 11

What is the definition of a zone of thermal comfort?

Answer 11

The temperatures at which an animal is most comfortable and productive, they use
no additional energy to maintain their core body temperature.

Question 12

What is a thermal set point and how does this change with a flu etc?

Answer 12

The level at which the body attempts to maintain its temperature. If you have the flu, a fever occurs, which is a temperature above the normal range due to an increase in the body’s temperature set point.

Question 13

Describe how to treat a hyperthermic dog?

Answer 13

• Aggressive cooling down to a temperature of 39.7°C
• Thermoregulation
• Cool intravenous (IV) fluids
• Blood work monitoring
• Anti-vomiting medication
• Anti-diarrheal medication
• Plasma transfusions
• Antibiotics (to minimize complications of bacterial translocation and sepsis)
• Blood pressure and heart rate monitoring
• Symptomatic supportive care
• Anti-seizure medication if needed

Question 14

How do cattle attempt to cool down at high temperatures?

Answer 14

Cattle at high temperatures will try to cool down using evaporation
of water and sweat. However in large groups, conditions are at higher
temperatures and levels of humidity, resulting in a lower vapour pressure/humidity gradient, so the
heat that can be dissipated from the cows is reduced. This may result in heat stress and water must be supplied to avoid dehydration.

Question 15

How should hypothermia be treated?

Answer 15

• Provide external warmth
• Provide internal warmth
• Reduce heat loss

Question 16

What are the causes of hyperthermia?

Answer 16

• exercise
• poor housing
• heat stroke
• malignant hyperthermia

Question 17

Outline the signs in hypothermia in lambs

Answer 17

Weak, hollow-flanked, lowered head, have poor suck reflex, slowly following or not following the ewe, lying down, coma and ultimately death.

39-40C is the normal temperature for
a lamb.

Treatment for hypothermia depends on the temperature and age of the lamb.

Question 18

What are the three types of hypothermia in lambs (include the temperature)? How are they treated differently?

Answer 18

Moderate hypothermia (37-39C)- vigorously dry the lamb with a towel, give warm colostrum, 50-100ml every two hours, warm the lamb under a heat lamp in a sheltered pen, return to the ewe and keep under close observation.

Severe hypothermia (less than 37C, less than five hours old)- dry the lamb thoroughly, heat up rapidly using a warming box with hot air (37-40C), give colostrum when the rectal temperature has come up to 37C, continue warming to 39C, return lamb to ewe and keep under close observation.

Severe hypothermia (less than 37C, more than fivehours old)- dry the lamb thoroughly, give intraperitoneal glucose, heat up rapidly by using a warming box with hot air (37-40C), give colostrum when the rectal temperature has come up to 37C, continue warming to 39C.