key themes Flashcards
what is cryostasis
a change in set point
give an example of cryostasis
when you are ill and develop a fever to fight infection
give an example of a positive feedback loop
giving birth - uterus contractions release hormones that increase contractions further
describe the concept of homeostasis
a self-regulating process by which biological systems maintain stability while adjusting to changing external conditions
a dynamic and steady state
example of negative feedback and explain how change is brought about
control of body temperature
temperature monitoring nerve cells detect change, which is registered by the temperature control centre, increased heat production occurs through shivering carried out by skeletal muscles until returned to set point
what are the 3 different types of adaptive response
acclimatisation, acclimation and adaptation
what is acclimatisation
changes within an individuals lifetime = phenotypic plasticity
when is acclimatisation most sensitive
early life
what is acclimation
changes induced experimentally
what is adaptation
evolution by natural selection, change over time
what is a biological constraint
something limiting the source of adaptive evolution
what 3 factors limit mammalian body size
metabolic demands
mechanical constraints
ability to thermo-regulate
what is the effect of increasing mass on metabolic demand and why
increased mass requires increased metabolic weight due to higher energy demand
what is the allometric law
a double in mass creates a 3/4 increase in metabolic rate
(expected increase is double)
who came up with the concept of allometric law
Kleiber, 1932
how do mechanical constraints limit body size
doubling size doubles the stress on the body
what is the equation for stress
stress = force / surface area
how are mechanical constraints combatted
increasing skeletal mass
what problem is associated with increasing skeletal mass
limited mobility
what is Bergmanns rule and when was it established
larger animals have smaller surface area to volume ratios - 1874
where are larger animals more likely to occur
at higher latitudes = cooler temperatures
3 benefits of small size
lower total food demand
lower skeletal pressure
easier to keep cool
3 benefits to large body size
lower food/kg demand
easier to keep warm
more energy reserves
what determines the upper limit in marine mammals
total food demand
why do structural constraints not impact marine mammals
they are supported by water
equation for force
force (N) = mass (kg) * acceleration (m/s^2)
equation for stress
stress (N/m^2) = force (N) / area (m^2)
1g in kg
0.001 kg
1 cm^2 in m^2
0.0001 m^2
