Endotherms and Cold + Coping with heat Flashcards
What are endotherms?
Have a body temperature primarily based on internally generated metabolic heat.
What is conduction?
Direct flow of heat between two material in contact, whether solid or fluid - rate of flow depends on temperature difference, contact area, conductive properties
What is Convection
flow of heat between 2 bodies from mass movement of intervening gas/liquid.
naturally faster than conduction
What is radiation?
Emitted by all bodies above absolute zero.
Rises very rapidly with surface temperature.
What is evaporation?
Losing excess heat by latent heat of vaporization
What is the thermoneutral zone?
The zone where the basal metabolic rate is constant
What is the relationship between body mass and critical temperature in birds and mammals
In general the larger the animal the lower the critical temperature.
bergmanns rule pointe out animals larger towards poles, because of this effect
How is fuel provided in migrating birds?
Usually in fat
Fatty acids combine with glycerol - form triglycerol
commonest lipid in body
Oxidation of fats provide energy , sparing glucose and muscle energy
Small birds can add up o 10% of body weight each day in fat
How are fats obtained?
absorption of ingested fats in intestine
result of lipogenesis in the liver
fats are transported in bloody and stored in adipose tissue
What is the 2nd method coping with cold temperatures in endotherms?
avoidance and microclimates example is Weddell seals avoiding extreme low temperatures by retreating under ice. Much warmer under ice. OR creating microclimate
e.g lemmings remain active in burrows under the snow,
windless, protection from predators
What is the difference between anabolism and catabolism?
Anabolism - chemical reactions combine simple smaller molecules into more complex, uses energy
Catabolism - break down complex molecules in simpler ones, releases energy
What is the advantage of burrowing in hot environments?
Only short distance from the ground temperature is fairly constant day/night - KANGAROO RAT IS EXAMPLE
What adaptations does the Kangaroo rat have to living in deserts?
Stays in burrow during day Metabolic water from dry seeds Free water in seeds Feces dehydrated before defecation Urine concentrated by countercurrent exchange- EXTRALONG LOOP OF HENLE
How does the antelope ground squirrel cope with heat?
Short periods of time foraging,
then retreating to burrow to cool
What are some locomotive adaptations to moving on hot sand?
Shovel snouted lizard keeps only 2 feet on ground, switches them all the time.
Sidewinding snakes!
What is aestivation?
polonged topor or dormancy during a hot period
amphibians, insects, fish
example: water-holding frog - aestivates in chamber 1m below surface
take down water with them
stable temp, stable environment
What are evaporators generally?
Middle sized animals, dogs, cats foxes
Humans, small temp changes result in substantial sweating increases.
What feature do many mammals including the Gazelles have to cool the brain?
Carotid rete - counter current heat exchange structure.
blood flowing to brain goes from carotid artery to small arteries within large venous sinus or cavity filled with cooled blood returning from nasal passages
Warm arterial blood gives up heat to cool venous blood, lowering blood temp going to brain.
What colour feature does the Gazelle have?
Often desert gazelles have black strip along flanks, white rumps.
Dark rumps facilitate heat gain when standing side on in early morning
White rump for reflectance at midday.
How do birds lose heat?
Dont have sweat glands, but use gular fluttering instead.
What are endurers?
Generally very large animals enduring Heat like Camels.
Examples:
camels can drink 200 ltrs water in 3 minutes
acting as a heat store body reduces evaporative water loss - adaptive hyperthermia.
What are the advantages of long loops of Henle?
Function to reabsorb water
Counter current exchage
Longer it is, more water re - absorbed,
higher concentration of urine
what are the adaptations of the desert insects?
impermeable integument and spiracles, low H2O loss
tolerate dehydration
uptake of H2O vapor, mouth and rectum - water fog, h2o trickles down into mouth through ridges on back
Uric acid - ability to store - helps conserve water
Regulation of water balance via excretory system achieved by Malphigian tubule in invertebrates
