15.3 Thermoregulation in endotherms Flashcards
what physiological changes do endotherms make to cool down?
- vasodilation
- increased sweating
- use of hairs
- anatomical adaptations
what is vasodilation and how does it decrease body temperature?
when arterioles near the surface of the skin DILATE when there is a rise in temperature
vessels CONSTRICT and push blood through the dilated arterioles which causes the skin to flush and cool due to increased heat loss through radiation
how does increased sweating decrease the body temperature?
as the core temperature increases, sweating increases
sweat covers the surface of the skin and evaporates which causes heat loss and the body to cool down
how do hairs on the skin decrease the body temperature?
as core temperature rises, the erector pili muscles in the skin RELAX and causes hairs to lie FLAT
this stops hot air from being trapped which REDUCES the body temperature
what anatomical adaptations do endotherms have to cool down?
they have large surface areas which maximises cooling
they have pale fur which reflects radiation
what physiological changes do endotherms make to warm up?
- vasoconstriction
- decreased sweating
- raising of hair/feathers
- shivering
what is vasoconstriction?
when arterioles near the surface of the skin CONSTRICT when there is a rise in temperature
vessels DILATE and keeps blood away from the surface of the skin which prevents heat loss
how does decreased sweating increase the temperature?
as the core temp falls, sweat production STOPS which reduces cooling
how do hairs on the skin increase the temperature?
as body temperature falls, erector pili muscles in the skin CONTRACT which causes hairs to STAND UP
the hairs trap hot air and insulates the skin causing it to heat up
how do hairs on the skin increase the temperature?
as body temperature falls, erector pili muscles in the skin CONTRACT which causes hairs to STAND UP
the hairs trap hot air and insulates the skin causing it to heat up
how does shivering cause the core temperature to rise?
as core temperature falls, the body shivers
shivering is when the large muscles in the body involuntarily contract and relax which generates metabolic heat which warms the body up
in cold environments what anatomical changes increase the body temperature?
- small ears which reduce the SA:V ratio and reduces cooling
- thick layers of fat to insulate the body
- hibernation periods to build up fat stores
