Give some features of ectotherms
- depend on environment
- metabolism is 10x lower than endotherms
- low energy intake
- narrow-wide enzyme functional temp
- sun basking and muscle activity (shivering)
Give some features of endotherms
- Independent of environment
- Metabolism is 10x higher then ectotherms
- high energy intake
- narrow enzyme functional temp
- hibernate
what features do Endothermic Homeotherms (Humans and other mammals) have
- Body surface often slightly lower temp than internal
- body core temp highly regulated
- size adjustments of body to change temp
Give the degrees for hypo/hyper-thermia
hypo = 35, hyper = 39, 37 degrees is perfect
What is the equations for metabolic heat production and what do the variables mean?
H = C (Tb - Ts)
H= metabolic heat production C = Heat loss Tb = Body core temperature Ts = Body surface
What steps happen when there is a temperature rise in the external environment?
- Temperature rise is detected by thermostat
- Thermostat activates cooling mechanism
- Sweat glands start to secrete sweat
- Sweat evaporates on skin and cools body
- blood vessels dilate increasing SA
- Increased SA allows more heat to escape
- Body cools, thermostat shuts off
What steps happen when there is a temperature dip in the external environment?
- Temperature dip is detected by thermostat
- Thermostat activates warming mechanism
- Muscles start to contract
- contraction causes shivering and generate heat
- blood vessels constrict decreasing SA
- decreased SA stops heat escaping
- Body warms, thermostat shuts off
How do organisms regulate temperature within the thermal neutral zone?
- Postural changes (cuddle up)
- Insulation (hair vs blubber)
- Vasomotor responses (blood flow regulation)
Give features of blubber
- No grooming required
- Metabollically available
- buoyancy doesn’t change with depth
- incompressible
- heavy
- skin near ambient temperature
Give features of Fur
- lightweight
- skin near body temperature
- compressed at depth
- requires air and grooming
- buoyancy changes with depth
- metabolically inert and unavailable
How do organisms regulate temperature below the lower cutaneous temp (LCT)?
Thermogenesis; Shivering, non-shivering (BAT), and countercurrent heat exchange.
What do white adipocytes do?
They convert Tri-glycerides into free fatty acids (FFAs)
What are white adipocytes?
Energy storing fat cells
How are FFAs converted to ATP?
FFAs are released into the blood and transported to mitochondria where they are oxidised into ATP by respiration.
What are brown adipocytes?
brown adipocytes are fat cells that express mitochondrial UCP (uncoupling proteins).
What do Uncoupling proteins do?
UCPs generate heat instead of ATP
Why are the fat cells brown?
They have large amounts of mitochondria and are highly vascularised
Where are brown adipocytes found?
Cold-acclimatised mammals/ hibernators/newborns
What does BAT stand for?
Brown adipose tissue
Describe the prices BAT goes though when it gets too cold
- Sympathetic stimulation from hypothalamus
- hydrolysis of triglyceride to FFAs.
- FFAs move into mitochondria and combine with ADP to produce ATP
- AKA FFAs are oxidised to ATP through beta-oxidation
- uses UPC 1 to leak protons from intermediate space of mitochondria back to the matrix - this produces heat
In counter current heat exchange which way does the heat flow?
From the artery to the vein
Where does the most counter-current heat exchange occur in birds
Their feet (are highly vascularised)
How is countercurrent heat exchange different in mammals?
Blubber insulates the body of the dolphin but it does not extend to the flippers so heat is transferred from the artery to the veins
How do organisms regulate temperature below the upper cutaneous temp (UCT)?
- Evaporative cooling
- sweating in some mammals and panting in birds and mammals
