5.1.1 Communication and homeostasis Flashcards
What is an ectotherm?
Animals which rely on the environment to warm their bodies and maintain their core temperature
What is an endotherm?
Animals that rely on their metabolic processes to warm their bodies and maintain core temperature
What is homeostasis?
Regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external changes (normally through negative feedback)
What type of response involved in temperature control is more common for ectotherms?
Behavioural
What are the behavioural responses to raise body temperature of ectotherms?
- Bask in the sun
- Orientate body to maximise SA exposed to sun
- Pressing body to warm ground
- Maximise movement to increase metabolic heat
What are the behavioural responses to lower body temperature of ectotherms?
- Seek shelter in shady areas with water
- Orientate body to minimise SA exposed to sun
- Press body against cool ground
- Minimise movements to reduce metabolic heat
What are the physiological responses of ectotherms? (Less common)
- Dark colours absorb more radiation
- Alter heart rate to increase or decrease metabolic rate
Why can ectotherms survive in habitats with limited food supplies?
Require less food than endotherms because they use less energy in regulating body temperature
Why do aquatic ectotherms have less difficulty in maintaining internal body temperature?
Water has a high specific heat capacity and so temperatures are constant
What type of response involved in temperature control is more common for endotherms?
Physiological
What is the physiological response to lower body temperature in endotherms? (Heat loss centre)
- Vasodilation
- Sweating
- Hair erector muscles relax
How does vasodilation work?
- Arterioles near surface of skin dilate
- Blood vessels (shunt vessel) deeper within skin constrict
- Blood flow to surface increased
- More heat radiates from surface
- Skin flushes and cools
How does increased sweating help to endotherms to cool down?
Sweat evaporates from skin and transfers heat
(Less effective in humid environment due to reduced concentration gradient)
How does flattening of hair help endotherms to cool down?
Avoids insulating layer of air from being trapped
What are the anatomical adaptations of animals in warm climates?
- Large SA to maximise heat loss
- Pale fur or feathers to reflect radiation
What is the physiological response to raise body temperature in endotherms? (Heat gain centre)
- Vasoconstriction
- Shivering
- Hair erector muscles contract
How does vasoconstriction work
- Arterioles near surface of skin constrict
- Blood vessels (shunt vessel) deeper within skin dilate
- Blood flow to surface reduced
- Less heat radiates from surface
- Skin pales and retains heat
How does shivering help to warm an endotherm?
Metabolic heat from exothermic reactions causing this relaxation and contraction warms body
What are the anatomical adaptations of endotherms in cold climates?
- Small SA
- Thick layer of insulating fat under skin
- Hibernation
What do peripheral temperature receptors do?
Detect changes in surface temperature - most likely to be affected by external conditions
What do hypothalamus temperature receptors do?
Detect changes in temperature of blood deep in body - most likely to be affected by internal conditions
What are the two control centres in endotherms?
Heat loss centre
Heat gain centre
What does negative feedback do?
Reduces the initial effect of the stimulus
What does positive feedback do?
Enhances the initial effect of stimulus
What is paracrine signalling?
- Between cells that are close together
- Signalling molecule e.g. glycoproteins
What is endocrine signalling?
- Between cells that are far apart
- Signalling molecule e.g. hormones
