thermoregulation

Thermoregulation

Is a homeostatic mechanism that enable organism to control their internal temperature within a set limit

define an endotherm

These animals rely on there own metabolic processes to provide at least some warming and usually has a body temperature higher than there surroundings. ( fancy way of saying warm blooded)

what are the 2 types of animals which are endotherms

mammals and birds

Ectotherms

These rely on there external environment to control their body temperature. They normally use structural ad behavioural mechanism / modifications which enable them to take advantage of there surrounding to maintain a reasonably body temp eg basking in the sun.( fancy name for cold blooded.

give some examples of ectotherms

• reptiles

• amphibian fish

• insect

in endotherms which areas are able to be cooler and which area has to main at a set temperature

the core has to remain as the set temperature this is due to the presence of vital organs eg brain heart and lungs.

The peripheral or extremities can be a a lower temp this can lead to frost bite in extreme cases.

what are the 2 advantages of being an endotherm

1. These are less effected by changes in the environments temperature as they are able to alter there metabolic rate to keep themselves at optimum temperature

2. There due to this there able to survive in different environments and remain active at all times of year in all season.

What’s a limitation

endotherms derive most of there body heat from there metabolism so have higher respiratory rates using up more glucose therefore require more food than ectotherms so harder to survive in habitats where there is less food eg desserts

what controls our temperature and where is it located

Our thermoregulatory centres and there found in the hypothalamus

what is the name of our 2 thermoregulatory centres and what is there role

heat loss centre= is activated when our core temperature rises. It sends impulses to several different effectors in the body to reduce core temperature

heat gain centre is activated when our core temperature falls. It sends impulses to several different effectors in the body to increase core temperature.

where do the thermoregulatory centres receive information from

2 types of thermoreceptors. One is in the hypothalamus which measures the blood temperature and the other is in skin receptors which monitor external temp

what happens when the our thermoregulatory centre receive information that our blood is to warm

• muscles in the arterioles relax causing vasodilation. More blood flows away from out core to the surface. where heat energy is lost by convection and radiation. This vasodilation causes us to turn red

• erector pili muscles in skin attached to hairs relax our hairs lay flat allowing air to circulate over the skin encouraging convection and evaporation

• we decrease our respiration in brown fat tissue

• The thyroid releases lower levels of thyroxine and the kidneys release less adrenaline lowering our metabiotic rate

• our behaviours change and we seek shade

what happens when the our thermoregulatory centre receive information that our blood is to warm

• muscles in arterioles contract causing vasoconstriction. less heat is carried from the core to the surface of the body maintaining a core temperature. extremities turn blue and frost bite can occur

• less sweat produced

• erector pili muscles contract raising hairs and trapping an insulating layer of warmer air next to our skin its not highly effective in humans

• brown fat tissue. non shivering thermogenesis. Increased respiration

• more adrenaline and thyroxine is released these metabolic rates increases

• behaviours curling and hudderling finding shelter putting on more clothes

those adaptations which prevent heat loss there are 2 types of methods use those which generate heat and those which generate it. what is the name of processes which generate heat

thermogenesis

name 3 conditions in which mammals can alter their set point in special circumstances

fever= white blood cells release chemicals called pyrogens as part of the inflammatory response to infection. These pyrogen raise the set point

hibernation = mammals release hormones that reduce set point

torpor = when there inactive animals like bats and hummingbirds reduce there set point.

name 2 consequences / types of homeostatic temperature control failure

hypothermia= occurs when heat loss exceeds heat generation due to prolong exposure to col temps. As the core temperature decreases the metabolic rate also decreases bellow 30 its fatal

hyperthermia= occurs when heat gain exceeds heat loss its causes dehydration. Rise in core temp causes increased metabolic rate. Above 40 degrees temp increases.