Test 3: Regulation of Body Temperature Flashcards
Is temperature uniform throughout the body? Explain the ‘parts’ of the body. What are their temperatures?
NO!
1) Inner Core:
- deep body temperature
- measured in the rectum
mammals: 36.5 - 39.5 * C
birds: 38 - 42 * C
2) Outer Shell
What fluctuations in temperature are normal for animals over a 24h period?
0.5-1.0 * C
What is the regular mammal core temperature?
between 36.5 * C and 39.5 * C
What is the regular bird core temperature?
between 38 * C and 42 * C
Explain the distrubution of temperatures in an organism under warm and cold environmental conditions.
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.
What influences body temperature?
metabolic rate
Explain the circumstances in which organisms may have hyperthermia. What is hyperthermia?
Hyperthermia- elevated body temperatures
- during excercise
- pregnant, lactating, rapidly growing animals
- thyroid hormone
What affects body temperature restraint?
- internal insulating layers (eg. white and brown adipose)
- external insulating layers (eg. hair and feathers)
What must be achieved in order for an organism to maintain a stable body temperature?
- a stable body temperature:
- heat inpute = heat output
Explain the metabolic rates in endothermic and ectothermic animals. What are they?
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
How do endothermic animals regulate their body temperature?
gain metabolic heat:
- cellular respiration
- muscular contraction
regulate:
- behaviour (ie. finding shade, panting, reduced activity)
Explain temperature variation over time. What happens in cold-blooded animals? Warm blooded?
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”)
What happens to all energy of an animal if it is:
- not growing
- not preforming physical work
- not pregnant
- not lactating
?
All energy released from nutrients is converted to heat.
How much faster can heat production become during muscle activity?
20 times higher than at rest
What is an example of involutary muscle contraction created to increase heat production?
shivering
How is heat loss regulated? By what? What acts as thermal insulators?
by controlling blood flow to the skin
- by the sympathetic nervous system
Thermal Insulators:
- skin
- fur
- feathers
- subcutaneous tissues (poor conductor of heat)
What do aquatic birds use to maintain a water-repellent plumage?
- fatty secretion
- from the uropygial gland
What do whales, seals and polar bears use to limit heat loss and remain in freezing water for long periods (without developing hypothermia)?
insulating layer of fat:
blubber
- in their subcutaneous tissue
Explain the correlation of heat production to body mass.
As heat production increases, body mass increases parallely.
By what 4 processes is heat transported?
- radiation
- conduction
- convection
- evaporation and condensation
What do all processes of heat transportation follow?
a temperature gradient:
warmer –> colder
Explain the “radiation” process of heat transfer.
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
What plays an important role in the absorption of visible light?
skin colour:
black- absorbs more solar radiation (90%)
white- (50% absorbed)
Explain the “conduction” process of heat transfer.
Conduction:
- heat transfer between objects in direct contact
- heat loss: body in contact with cooler surface
Explain the “convection” process of heat transfer.
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
Explain the “evaporation” process of heat transfer. State examples of this process.
Evaporation:
- water –> gas / water vapour
- cools animal
- eg. sweating, panting, wetting of body surface
Explain the 4 processes using a dog in a pool.
- 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.
What is the ‘optimal temperature zone’ called? What is it in other words?
the thermoneutral zone:
- most energetically efficient zone
What is hyperthermia?
When heat production exceeds heat loss.
- body temperature rises above normal ranges
What is hypothermia?
When the increase in body temperature is not sufficient to compensate for the heat lost.
- body temperature deops below normal ranges
What is a fever? When does it occur?
- raise in body temperature
- occurs during infections and injuries
State examples of predisposing factors that increase an animal’s risk for hypothermia.
- 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
State examples of predisposing factors that increase an animal’s risk for hyperthermia.
- increased ambient temperature
- humidity
- excessive muscle exertion
- excessive metabolic activity
- physical structure
- dehydration
- trauma
- restraint
State clinical signs of hyperthermia.
- increased heart rate
- increased respiration
- open mouth breathing
- increased sweat and saliva
- weakened pulse
- restlessness
- slow responsiveness
- uncoordination
- convulsions
- collapse
- death
State clinical signs of hypothermia.
- shivering
- slow shallow breathing
- weakness
- lethargy (lack of energy and enthusiasm)
- low blood pressure
- muscle stiffness
- dilated pupils
- hard to fins heartbeat
- coma
How is body temperature regulated?
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.
State examples of sensory inputs of body temperature regulation.
warmth and cold sensors in:
- skin
- internal organs
- hypothalamus
State examples of motor outputs of body temperature regulation.
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
Explain vasoconstriction and vasodilation in terms of body temperature regulation.
Vasodilation:
- increased blood flow to skin surface
- increased heat loss
Vasoconstriction:
- decreased blood flow to skin surface
- decreased heat loss
