environmental interactions Flashcards
three types of changes
enviromental- cyclical
diurnal-daily
seasonal-anual
duinal (daily changes)
-night day
-walking eating ETC
set circadian rhythms to
-metabolic rate
-body temp
-mental activity
seasonal changes
photoperiod (dday length)
metabolism
the total of all chemical processes in the organism
measuring metabolic rate(MR)
- direct calorimetry: the metabolic rate at the rate which heat is lost from the animal
- indirect calorimetry: rate at which 02 is used or CO2 is produced per unit of body tissue
by measuring MR we can
How much energy gained from food is required
to stay alive (BMR)
-How much energy is available to us for ‘nonessential’
function
-How energy use changes in response to various
challenges
basal metabolic rate (BMR)
the minimum rate in which is required to maintain basic functions
BMR must be measured under conditions of
-at rest
-empty somach
-thermoneutral
-not growing
-no stress
expressed as daily rates of energy expenditure or O2 consumption
RMR: resting MR
less strict conditions to measure. defined as existing in a neutral temperature
environment while in the post-absorptive state expressed as daily rates of energy expenditure orO2 consumption
factors effecting MR
food intake age activity level psychological state ambient temp
ectothermy
do ont use MR to keep warm
endothermy
use heat generated by MR to keep warm
energy expensive
can stay active in a wider range of temps
MR and body size
large = higher MR but more efficient
-cost of maintain one unit/KG is lower than that of smaller animals
the metabolic rate in the TNZ is = to
BMR
heat exchange occurs in for ways
– Radiation
– Conduction
– Convection
– Evaporation
radiation
– the emission of electromagnetic waves
by all objects
conduction
the direct transfur of heat through molacules in contact
convection
transfur of heat by movement of a fluid or air past a surface
- wind
- water
evaporation
the transfur of heat from water evaporating froma surface
factors effecting heat exchange
surface area
thermal conductance
temprature differnce between surfaces
responses to heat in NZ
-seeking water shade or shelter
responses to upper critical temprature (UCT)
increase in MR
- vasodilation
- evaporation heat loss increase
managing heat stress
cool and fresh water
- housing
- feeding less but more often at cooler times of the day
Counter-current Heat Exchangers
a special arengement of blood vessels in extremities
