Thermoregulation

Question 1

heat input

Answer 1

Metabolism
External sources/radiant heat sources

Question 2

heat output

Answer 2

Radiation
Evaporation
Conduction
Convection

Question 3

Basal metabolic rate (BMR) =

Answer 3

minimal rate of energy metabolism measured under minimal stress while the animal is fasting

Question 4

warm conditions vs cold conditions

Answer 4

Warm conditions:
Core body temperature extend to limbs and skin surfaces

Cold conditions:
Core body temperature restrict to cores and extremities

Question 5

core body temperature

Answer 5

deep tissues (abdomen, thorax, brain)

Question 6

shell body temperature

Answer 6

peripheral tissues

Question 7

under warm condition

Answer 7

Heat is transferred by countercurrent exchange from warm arterial blood to cooler venous and return to normal temperature

Carotid rate in sheep and horse (carotid artery and veins from rete)

Question 8

increased body temperature is sensed by_______

Answer 8

THERMOREGULATORY CENTER in the HYPOTHALAMUS = increases blood flow to the skin to induce sweat

Question 9

Hypothalamus initiates:

Answer 9

Thermal receptors in the skin
Changes in hypothalamic blood temp
Nervous signals from osmoreceptors and pressure receptors of blood volume
Hormones: adrenal and thyroid hormones

Question 10

hypothermia

Answer 10

Body temperature decreases = heat loss increases production or gain

Newborns have undeveloped thermoregulatory ability
soiled or moistened hair coat, restraint on a cold surface, prolonged immobility, chemical restraint drugs & anesthesia

prolonged exposure to cold temps

Question 11

hyperthermia

Answer 11

Excessive elevation of core temperature (no fever)

Predisposing factors:
Increased ambient temp
Humidity
Excessive muscle exertion or metabolic activity
Dehydration
Trauma
Restraint

prolonged exposure to high heat conditions

Question 12

hyperthermia vs fever

Answer 12

hyperthermia: elevation of the body temp above the hypothalamic set point due to failure of the body’s heat dispersing mechanism

fever: elevation of body tem due to resetting of the hypothalamic set point in response to endogenous or exogenous pyrogens

Question 13

heat stress increases and decreases?

Answer 13

increases = respiration rate, rectal temp, water intake, sweating

decreases = rate of feed passage, dry matter intake, blood flow to internal organs, milk production, reproductive performance

Question 14

Effects of heat stress on welfare of dairy cattle

Answer 14

Reduced feed intake
Change of feeding pattern
Cattle stand rather then lie down
Bunching or congregating in shade if it’s available
Rapid shallowing breathing; open mouth (panting)
Respiration rates increasing with temperature
Increased water intake

Question 15

Heat stress on reproduction

Answer 15

Estrous cycle
Conception rate
Embryonic development
Sperm production

Question 16

Effect of heat stress on poultry

Answer 16

Increased mortality
Productivity losses
Lost fertility
Increase in metabolic disorders
Lower resistance to disease:
Suppression of the immune system
Adding capital investment (costs increase)

Question 17

Strategies for managing heat stress for bovine & poultry

Answer 17

bovine:
Water
Shade
Fan
Sprinkler and fans

poultry:
Increase cooling system
Reduce number of bird per cage/pen/group
High energy feeds
Addition of antioxidant in diet
Electrolytes’ supplementation

Question 18

Shivering is a form of________.
Radiation
Thermogenesis
Osmoregulation

Answer 18

Osmoregulation

Question 19

Heat is lost from the skin of a mammal on a hot day by the _______.
Movement of the skin capillaries nearer to the surface
Relaxation of the arterioles so the skin capillaries carry more blood
Opening of the pores of all the sweat glands

Answer 19

Relaxation of the arterioles so the skin capillaries carry more blood

Question 20

Increase in muscle contractions along with an increased rate of heat production is called _________.
Shivering thermogenesis
Non-shivering thermogenesis
Overlapping hypogenesis

Answer 20

Shivering thermogenesis

Question 21

Which of the following applies to a person who moves from a temperate to a tropical area to live?
During the first fe weeks in the tropical area, his/her sweat rate will rise
The salt content of his/her sweat will fall
his/her rate of urine production will fall

Answer 21

During the first fe weeks in the tropical area, his/her sweat rate will rise