Homeostasis Flashcards
homeostasis
maintenance of nearly constant conditions in the internal evironment. involves control of vital parameters.
steady state
maintenance of nearly constant conditions over time. not the same as equilibrium
equilibrium
solute concentrations and other parameters are constant in time without requiring input of energy from metabolism or other sources
basal metabolic rate
energy expenditure at rest. largest proportion of our daily energy use. lowest during sleep and increases with arousal and fever, after ingestion of food and with normal activity
resting metabolic rate
2100 kcal/day for a 70kg man. amount of calories required to sustain daily resting metabolism. 5% higher in males than females. declines with age due to reduced muscle mass.
anabolic
formation of substances
catabolic
breakdown of substances
negative feedback
major process used to maintain a stable internal environment
positive feedback
accelerates a process
feedforward control
regulates body systems, especially when a change with time is desirable (ex. heart rate and breathing increases in anticipation of exercise)
end product inhibition
product formed from a substrate by an enzyme negatively feeds back to inhibit further activation of the enzyme
thyroid hormone secretion
regulation of thyroid hormones from the thyroid gland. TRH from hypothalamus acts on anterior pituitary gland to release TSH. TSH stimulates thyroid gland to secrete T3 and T4. T3 and T4 increases basal metabolic rate and provides negative feedback to anterior pituitary.
gain
capacity of the system to restore a controlled variable to its set point after a perturbation (deviation). the higher the gain of the system, the better able it is to restore a controlled variable.
