Homeostasis Flashcards
any self-regulating process by which an organism tends to maintain stability while adjusting to conditions that are best for its survival
Homeostasis
adjusting of physiological system within the body
homeostatic regulation
Three parts/ mechanisms of homeostatic regulation
- Receptor
- Control center
- Effector
receives information that something in the environment is changing
receptor
- aka integration center
- receives and processes information from the receptor
control center
responds to the commands of the control center by either opposing or enhancing the stimulus
effector
Two (2) types of feedback
- Negative feedback
- Positive feedback
- the response will reverse or cause the opposite effect of the original stimulus
- the result of a reaction is reduced to bring the system back to a stable state
negative feedback
- occurs in nature when the product of a reaction leads to an increase in that reaction
- In homeostasis, it moves a system further away from the target of equilibrium
positive feedback
example of negative feedback
regulation of the blood calcium level
example of positive feedback
- Childbirth – stretching of uterine walls cause contractions that further stretch the walls (this continues until birthing occurs)
- Lactation – the child feeding stimulates milk production which causes further feeding (continues until baby stops feeding)
organisms that keep their internal fluids isotonic to their environment, that is, they maintain an internal salinity similar to their ambient conditions
Osmoconformers
organisms that actively regulate their osmotic pressure, independent of the surrounding environment
Osmoregulators
Examples of osmoconformers
- starfish
- crabs
- jellyfish
Example of osmoregulators
freshwater fish
Other homeostatic mechanism
- Osmoregulation
- Thermoregulation
- maintenance of water balance
- organisms regulate osmotic pressure of their body to prevent body fluids from becoming too diluted or too concentrated
osmoregulation
- maintenance of the body temperature
- organisms are able to keep their body temperature within a certain range
thermoregulation
animals succeed metabolically only in a ___ range of temperature
restricted
too low temperature, metabolism ___ ___, energy production is ___
slows down
reduced
too high temperature, metabolism is ___, enzymatic activity is ___
unbalanced
hampered
any so-called cold-blooded animal—that is, any animal whose regulation of body temperature depends on external sources, such as sunlight or a heated rock surface
Ectothermic animals
examples of ectothermic animals
- fishes
- amphibians
- reptiles
- invertebrates
animals that are able to maintain a constant body temperature regardless of their ambient temperature
Endothermic animals
examples of endothermic animals
- all birds and mammals
- some fishes
Two types of adjustment in ectothermic animals
- Behavioral Adjustment
- Metabolic Adjustment
seeks areas where temperature is favorable
behavioral adjustment
adjust metabolic rates to the prevailing temperature
metabolic adjustment
body temperature range of mammals
36°C - 38°C
body temperature range of birds
40°C - 42°C
constant temperature of endothermic animals is maintained by a delicate balance between ___ ___ and ___ ___
heat production
heat loss
living mainly in the ground
fossorial living
active at night
nocturnal living
Adaptations for hot environment
- fossorial living
- nocturnal living
Adaptations for cold environment
- decreased conductance
- increased heat production
reduction of heat loss by increasing the effectiveness of the insulation
decreased conductance
example of decreased conductance
- fur thickness increases in winter
- countercurrent heat exchange between outgoing warm blood and returning cold blood
example of increased heat production
- augmented muscular activity through exercise or shivering
- nonshivering thermogenesis by increased oxidation of foods especially from stores of brown fat
an opening beneath the snow where small mammals live during winter, with connecting tunnels made by them to travel through, hunt prey, and gather plant material
subnivean zone
entering a prolonged and controlled state of dormancy
hibernation
- “summer sleep” state of dormancy on a hot season
- slowing down of the activity and metabolism during a hot and dry season (such as summer).
aestivation
maintain high body temperature when active, but allow temperature to drop profoundly when inactive and asleep
daily torpor
- called daily torpor
- provides enormous saving of energy to small endotherms that are never more than a few hours away from starvation at normal body temperatures. Hummingbirds also may drop their body temperature at night when food supplies are low
adaptive hypothermia
animals that undergo adaptive hypothermia
- mammals
- birds
