Homeostasis Flashcards
What best describes the limits to life on earth?
the freezing point of water and the temperature when proteins denature (0 - 40 degrees Celsius)
If the Q10 of animal’s metabolic rate is 2, then –
the animal consumes 1/2 as much oxygen per hour at 20 degrees then 30 degrees Celsius
What statement about brown fat is true?
it produces heat without producing much ATP
What’s the most important and most general characteristic of endotherms adapted to cold climates compared with endotherms adapted to warm climate?
greater insulation
what would cause a decrease in the hypothalamic temperature set point for metabolic heat production?
taking an aspirin when you have a fever
Because of their – endotherms expend more energy (thus more heat) just to maintain the ion concentration gradients across their membranes
leaky membranes
sum of total energy expenditures in body at rest
metabolic rates
True or False: behavioral thermoregulation is exclusive to ectotherms
False
energy budget
heat in = heat out
metabolism + R in = R out + convection + conduction + evaporation
surface temperature can be controlled by altering the – to the skin
flow of blood
mammals have specialized blood vessels for transporting heat to –
hairless surfaces of the skin
cold fish: heat that blood picks up from metabolically active muscles is – to water flowing across its gills
lost
hot fish: heat rows from warm blood to cold blood by –
conduction
the internal body temperature of a hot fish is – than water temperature
greater
for hot fish, 10 degree Celsius increase in muscle temperature, increases fish sustainable power –>
faster
True or False: Some ectotherms regulate metabolic heat production
true (insects - scarab beetle, worker bees)
How to determine metabolic rate by measuring what?
oxygen consumption or carbon dioxide production
within a narrow range of environmental temperature, the metabolic rates of endotherms are at low levels and independent of temperature
thermoneutral zone
resting animal is consuming enough energy to carry out its minimal body functions
BMR
BMR of elephant is – than the BMR of mouse
greater
BMR per gram of tissue increases as an animal gets –
smaller
Endotherms respond to cold by producing – and adapt to cold by reducing –
heat, heat loss
birds only use – heat production
shivering
non shivering heat production occurs in –
brown fat cells
thermogenin is found in
brown fat cells
brown fats are – in some adults
small
– can be found in animals acclimatized to cold or hibernation
brown fat cells
most common and important means of decreasing heat loss
increasing thermal insulation
other ways to decrease heat loss include
decrease blood flow to skin (constriction of blood vessels in skin) and countercurrent heat exchange
for exercising animals, overheating can occur even at
low environmental temperatures
sweating and panting are – process that require expending metabolic energy (generate heat in the process of dissipating heat)
active
slight cooling of hypothalamus
constriction of skin blood vessels
stronger cooling of hypothalamus
increases metabolic heat production
heated hypothalamus
metabolic rate and body temperature falls and favors heat loss
hypothalamus itself is a major – that generates set points for thermoregulation responses
feedback signal
change in skin temperature is a – that shifts hypothalamic set point
feedforward information
hypothalamic set point – when awake or active
increases
set point for metabolic heat production is – when skin is cold
higher
a rise in body temperature in response to pyrogens
fever
pyrogens like foreign proteins produced by bacteria or virus
exogenous
pyrogens like substances produced by immune cells in response to infection
endogenous
during a fever, the body temperature rises until you match –
new set point
aspirin – set point to normal so you feel –
lowers, hot
some animals conserve energy by turning –
down thermostat
below normal body temperature
hypothermia
some animals undergo – to survive periods of cold and food scarcity
regulated hypothermia
regulated hypothermia can last for
days or even weeks
some small endotherms with high metabolic rates such as hummingbirds can survive without food (normally inactive)
daily torpor
body temperature falls close to ambient temperature (1/15 of BMR)
hibernation
