Thermoregulation - Physiological basis of temperature regulation. Flashcards
Where are temperature receptors located in the live animal?
Hypothalamus and mid-brain Skin Viscera Around major veins Spinal cord
What type of feedback is thermoregulation based on?
Negative feedback
How does vasodilation result in heat loss?
Arterioles dilate–>increased capillary blood flow–>Increased temperature gradient–>decreased tissue insulation
What happens to the set point of the hypothalamus during excercise?
It increases and temperature is regulated at this level for the duration of excercise. This is initiated by a rise in core body temperature due to the excercise.
How is sweating regulated?
Through sympathetic innervation and catecholamines.
Aldosterone affecs the solute reabsorption.
What are the two categories of young?
Precocial - ready to go
Altricial - immature at birth, need a nest!
What is the role of brown fat in thermoregulation, with particular reference to pregnacy?
After placental seperation and the shock of being born into a cold environment, chemicals are released which result in increased activity of mitochondrial uncoupling protein in the brown fat. This uncouples ATP synthesis from electron transport so oxidation of fatty acids produces lots of heat. This is known as non-shivering thermogenesis.
Why is an animal at particular risk of hypothermia during surgery?
Aneasthetic affects set point of hypothalamus.
Animal is shaved
Animal is wet from surgical spirits
Animal is on a cold/conducting operating table
Animal is open => heat loss from within body
How is a fever brought about?
Direct effect of cytokines produced by leukocytes
Indirect effect of these cytokines leading to PGE2 production which is a pyrogen.
What are types of physiological adaptations to cold?
Cold acclimation - short term changes
Cold acclimitization - long term changes e.g. increasing insulation and changing vasomotor function
Climatic adaptation - genetic
Allowing temperature to drop e.g. diurnal variation, torpor, hibernation.
How do animals ‘wake up’ from hibernation?
By using their brown fat stores.
How can an animal adapt to hot weather?
Changing behaviour
Climatic adaptation
Bodily temperature fluctuation
Conserving water
What should be considered whn designing an animal house?
Air flow
Thermal properties of the builing materials
Ability to exhibit normal behaviours
Availability of water.
