homeostasis Flashcards
define homeostasis
the maintenance of a constant or unchanging internal environment
what does the sensor do
measures the value of the variable
what does the control centre do
compares the value being set with what it should be and what the effect of that should be
what does the effector do
the action to determine the value of the regulated variable.
corrects the disturbance
what is negative feedback
a response to a change in the opposite direction
what is normal blood sugar level, low and high
normal = 4-6mmol/L low = <4mmol/L high = >7mmol/L
what detects a rise in blood glucose level? and what is the reaction to this
beta cells in islets of Langerhans in pancreas. these secrete insulin into the blood
what does insulin stimulate the liver to do?
take up glucose and store it as glycogen
what detects a fall in blood glucose levels? what is the reaction to this?
detected by alpha cells in islets of langerhans in pancreas. causes release of glucagon into the blood which targets the liver
what does the release of glucagon cause the liver to do?
liver breaks down glycogen stores and releases glucose to the blood
what happened to the body’s core temperature during exercise
temperature increases. negative feedback reacts and reduces core temperature
what happens to blood concentration of oxygen during exercise
demand increases as it is used in the metabolic pathway in resynthesising ATP to allow muscle contraction. blood conc of oxygen therefore decreases
