thermoregulation Flashcards
why is tempreture so important to creatures?
creature have a narrow range of temptreture they can function at, when ouside of their range function can stop or cells can die
What is an ectotherm
Maintains heat by reacting to the external sources, their bodies can tolerate a wider range of temperature and are more energetically efficient. However when they are cold they are at higher risk of predation.
what is an endotherm
animals generate heat through metabolic processes, while this uses more energy this also means that they can be more adaptive to the temperature.
list the four ways of heat exchange occurs
convection, conduction, radiation, evaporation
what is convection
Heat moving from an object into an external fluid. Heat transfer depends on the thermal gradient.
what is evaporation
heat lost on surface through moisture evaporation
what is radiation
Infrared thermal radiation, this is highly dependent on the colour
what is conduction
Heat transfer through direct contact, the rate depends on the thermal gradient. (lizard and rock)
list types of adaptation animals may have to help thermoregulation
fur, feathers, dense, thickness and length, types of hair. some feather have waterproof qualities. skin, thick with blubber and even colour
how have penguins adapted to the cold
they have long and thick feathers that are densly packed.
describe how polar bear have adapted
thick, dense and long hair for insulation. thei skin is very thick with lost of blubber in the hypodermis (FAT). and their skin in black under their skin.
how have raindeer adapted to the cold
they have thick fur and the ablility to grow a winter coat for when snow arrives.
describe the countercurrent mechanism
fluid flow in oppsite direction causeing heat exchange.
describe shivering
involantary muscle temours (10/sec) this increases oxygen use by 400%.
describe non shivering thermogenesis
- increasing hirmone regulation (adrenoline, noradrenaline, thyroxine) this increases metabolism and energy useage which increases tempreture.
- brow fat (in young) is burned quickley to increases tempreture
describe brown fat and why it is unique
Brown fat has a high concentration of mitochondria, presence of cytochromes (iron makes the brown colour), the fat are in small bundles. When they are burned the energy is used directly for heating.
describe the thermoneutral zone
Range of which endothermic animals can maintain temperature without altering their heat production, thus the other body temperature is equal to the core body temperature.
descirbe the critical temptretures
Lower critical temperature: the minimum body temperature that can be tolerated by an organism.
Upper critical temperature: the maximum body temperature that can be tolerated by an organism.
Describe the role and location of the sensors of thermoregulation
Peripheral - skin, tempreture sensative neurons which react to both hot and cold
Central - Viscera in the gastrointestinal tract, drinking cold/hot fluids stimulate these receptors.
both of these connect the the hypothalamic control centre
list some heating mechanisims
Behavioral (burrows ect)
Insulation (hair)
Reduced blood flow to skin
Countercurrent exchangers
Reduces heat loss via conduction, radiation/ convection/ evaporation
Increase internal heat generation-Unique to endotherms, metabolic activity
list some cooling mechanisims
Decrease insulation
Vasodilation
Increase evaporation
Avoidance behaviour
Anatomical reduction in heat gain
what is hyperthermia
Hyperthermia is unregulated rise of body temperature caused by environmental conditions. Input of heat from the environment needs to exceed heat output from the body.
- 44 degrees is fatal
what is a fever and what causes it
Fever is elevation of body temperature as a result from infection or inflammation. The WBC releases pyrogens which increase temperature and kill foreign pathogens. Hypothalamus now maintains that new heated temperature caused by the pyrogen until the pathogen is killed. To do this the body shivers, peripheral vasoconstriction and piloerection.
describe how metabolism is used to heat bodies
Increase blood flow
Increase reactions (produces heat)
Increasing fat production to boost insulation
Constriction of blood vessels to protect vitals
Shivering
Brown fat cell usage
describe how metabolism is used to cool bodies
Blood vessel dilation to radiate heat
Sweating
how is the brain protected from tempreture in mamals
The rete mirabile uses the cool blood from the nose to cool the arterial blood entering the brain through countercurrent exchange..
what is the effect of the stimulation of the piloerector muscle
the hair stand on end, traping radiation heat from the body, also prevent convection from the surrondings
