endothermic regulation Flashcards
where does the hypothalamus receive information from?
- thermoreceptors in the hypothalamus
- peripheral thermoreceptors in the skin
what do hypothalamus thermoreceptors do?
detect temperature of the blood as it passes through the brain
what do peripheral thermoreceptors do?
detect temperature of external air at skin surface
what is the role of thermoreceptors?
send nerve impulses along sensory neurones to the hypothalamus which sends impulses along motor neurones to effectors
what do effectors do?
respond to restore body temperature back to normal
what is the role of the hypothalamus?
keeps core body temp in dynamic equilibrium (37 degrees)
what is the main advantage of having two different thermoreceptors in different locations?
allows body to respond to change throughout the body
how do endotherms regulate body temperature
through a nervous response
state the path of travel for nerve impulses
sensory neurone –> brain –> hypothalamus –> effector
how does sweating regulate temperature?
- increase in water
- increases latent vaporisation
- acts as a cooling effect
how does vasodilation regulate temperature?
- arterioles dilate due to muscle contraction
- constricts vessels supplying capillaries
- increases blood near skin surface which radiates more heat energy
- increases temperature
how does vasoconstriction regulate temperature?
- arterioles near skin surface restrict
- decreases blood near skin surface and increases further away
- less heat energy radiated
- decreases temperature
how does shivering regulate temperature?
- muscles relax & contract
- increases respiration
- more heat energy is released
- increases temperature
what are the two hypothalamus control centres?
heat loss and heat gain
describe the heat loss centre
- activated when blood temp flowing through hypothalamus increases
- impulses are sent along an autonomic motor neurone to effectors
- response is triggered to lower core body temp
describe the heat gain centre
- activated when blood temp flowing through hypothalamus decreases
- impulses are sent along an autonomic motor neurone to effectors
- response is triggered to raise core body temp
give examples of endotherms
mammals, birds
given examples of ectotherms
fish, amphibians, reptiles, invertebrates
state 5 factors that affect organisms temperature
- exothermic chemical reactions
- latent heat of evaporation
- radiation
- convection
- conduction
explain latent heat of evaporation
objects cool down as water evaporates from its surface
explain radiation
the transmission of electromagnetic waves to and from the air, water or ground
explain convection
heating and cooling by currents of air or water (warm rises, cold sinks)
explain conduction
heating due to molecular collisions (best in water and ground)
state 3 behavioural responses of ectotherms
- absorb radiation from sun
- conduction
- hide in shade / move into water or mud
state 3 physiological responses of ectotherms
- dark coloured skin (absorbs more radiation)
- alter heart rate to regulate metabolic rate and affect warming/cooling
- require less food
what is an ectotherm
an organism that uses its surroundings to warm its body - core body temp heavily reliant on environment
what is an endotherm
an organism that relies of metabolic processes to warm their bodies - able to maintain stable core body temp regardless of environment temperature
state 4 rapid responses for warming up
- vasoconstriction
- decreased sweating
- raising body hair or feathers
- shivering
