Animal - Section D - Thermoregulation Flashcards
Heat production =
&
Heat transfer =
A. Thermogenesis
B. Thermoconductance
Behavioural mechanisms
- Heat production - exercise
- Heat transfer - basking, retreating, posture
Physiological mechanisms
-Heat production
Increase metabolic rate
Shivering thermogenesis
Non shivering thermogenesis (mammal specific)
Physiological mechanisms
- Heat transfer
- Control of peripheral blood flow
- activation of piloerector muscles (increase thickness of pillage)
- Sweating and panting (evaporative cooling)
Potential environmental factors which might affect thermal regulation of an animal in an environment like the below
Define these thermoregulation terms
-Homeotherms
-Poikilotherm
-Endotherms
-Ectotherms
Homeotherm - Body temp stays constant
(Mammals & Bird)
Poikilotherms - Body temp varies with the environemtnal temp
(Reptiles & amphibians)
Endotherm - High metabolic heat production and less reliant on environmental heat to raise body temp.
(Mammals/Bird)
Ectotherm - Rely on external environmental heating as the metabolic heat production is low
(Reptiles/Crocodile basking dependant on sun basking for heat)
Antartic fish
Most poikilothermic ectotherms are fish…
In the case of this antartic fish there is a very stable environment which makes it a homeothermic ectotherm.
(very stable body temp but still ectothermic)
Can’t generate its own heat so relying on external heat (not that there is alot in antartica) but thats what warms the body and stops the anmial freezing.
Stable body temp of -1.8°C year round
Tuna are warm blooded fishes but are both
poikilothermic and homeothermic
This combo is known as?
Mesothermic
Leatherback turtles are warmblooded reptiles
- Maintain their body temp about 18°C higher than surrounding sea
- Very large body so low surface area to volume ratio so they don’t lose heat that quickly
- Also very active swimmers so they generate alot of internal heat
- Also counter current blood vessels in flippers which act as heat exchangers so they’re not losing alot of heat through their flippers
Galapagos marine iguanas are a
poikilothermic/homeothermic ectotherm.
How do they adjust their body for cold sea temps and warm terrestrial environments?
Reduce heat loss during dive by
1. Peripheral vasoconstriction
- Peripheral vasoconstriction occurs to allow the body to retain core heat for longer as protection against hypothermia by allowing the skin to act as an insulating layer between core organs and the water. It also allows more oxygen to be delivered to important and oxygen-sensitive organs such as heart and brain.
2. bradycardia
- Abnormally slow heart action
Increase heat gain after dive by:
1.Peripheral vasodilation
Blood vessels open near the epiderm and the Iguana absords heat from the sun which in turn warms the blood close to the epiderm which then returns it back to the core to circulate warm blood around the body,
2.Tachycardia
A heart rate which exceeds resting (fast)
Whales and Dolphins are homeothermic endotherms
Explain how they:
- Reduce heat loss in water
- Control thermal conductance
- Reduce heat loss in fins
Reduce heat loss in water by high metabolic rate and low thermal conductance (heat exchange with environment) because of thick blubber layer
- Control thermal conductance by controlling peripheral blood flow, they can shunt blood either below the blubber layer to conserve heat or they can shunt blood to the outside closer to the surface in order to lose blody heat if they are to hot.
- Reduce heat loss in fins by using the rete mirabile.
In the case of whales and dolphin fins its the warm arterial blood coming from the body core that is exchanging it heat with the cold venus blood coming back from peripheral.
- True homeothermic endotherms
- They have this morphological adaptation of the counter current blood vessels in their fins in order to reduce heat loss because the fins are ver large/big surface area where you could potentially lose alot of heat.
Naked mole rat
-mammal (cold blooded)
truly poikilothermic (no ability to regulate body temp)
body temp vs amient temp
Native to Ethipoa.
They have no ability to regulate their body temp because of where they live in sub terrain colonys where they live their entire life underground feeding on large tubus of an underground plant which provide them with water and food.
- Don’t feel pain
- Don’t get cancer
- Unique social structure similar to bees
(one breeding female)
When are thermoregulatory responses stimulated?
When the body temp is outside the thermoneutral zone.
TNZ for a naked human male is 25-30
(thermo neutral zone)
(NEGATIVE FEEDBACK HOMEOSTASIS)
- Disturbance - Sprinting
- Detector - Body Thermostat
- Control System - Hypothalamus
- Effector aka bodily response - Sweating
What is Shivering thermogenesis?
A thermoregulatory response which activates heat in the muscles.
1. Imbalance in homeostasis
2. (NEGATIVE FEEDBACK HOMEOSTASIS)
- Disturbance - Cold exposure
- Detector - Body Thermostat
- Control System - Hypothalamus
- Effector aka bodily response - Shivering
What is Non-shivering thermogenesis?
Specialised tissue (brown fat) contains huge quantities of mitochondria.
Increased metabolic work in this tissue is stimulated by sympathetic innervation.
The normal biochemistry of metabolism is altered so that heat can be produced without the production of ATP.
Pyrogens - Fever inducing substances after the hypothalamic temperature set point.
What is behavioural thermoregulation?
-Herding
emperor penguins - chicks and adults huddle together and rotate from inner to outter circle so nobody freezes to death on outside
honey bee - swarm density depends on temp
(clump together and shiver wing muscles to maintain heat, when warm they disperse more to allow air flow through the swarm)
-Posture
Polar bears in wind chill curl up like a dog
Dogs splay when to hot
Ground squirrels use their tails as a sun shade with back to the sun
Antelope turn to face to or away from the sun
