response and regulation Flashcards
what is homeostasis
the maintenance of stable internal environment in the body despite fluctuations in internal and external conditions
why is homeostasis important
to ensure optimum conditions for enzymes and cellular processes in the body
what type of chemicals help to ensure optimum conditions within the body
hormones
what is a hormone
a cell signalling molecule produced by the endocrine glands and released into the blood
travels to a target organ and binds, initiating a response
what conditions in the body must be controlled by homeostasis
temperature
blood glucose concentration
water levels
why must body temperature be controlled
enzymes work best at their optimum temperature
deviations from optimum temperature decrease the rate of enzyme-controlled reactions
what is the optimum temperature for enzymes in the human body
37°C
what responses occur when the body temperature rises above 37°C
vasodilation
sweating
erector muscles relax, hairs lie flat
where is sweat produced
sweat glands
how does sweating help reduce body temperature
heat energy is used to evaporate sweat. increased heat transfer from the skin to the environment decreases body temperature
what is vasodilation
dilation of blood vessels near the skin surface
blood flows closer to the skins surface
greater heater loss to the surroundings
outline the responses when the body temperature decreases below 37°C
vasoconstriction
shivering
hair erector muscles contract
little sweat is produced
how does shivering help increase body temperature
involuntary contraction of muscles generates heat from respiration.
how does the contraction of hair erector muscles help increase body temperature
hairs stand on end creating pockets of air between hairs and a layer of insulation
what is vasoconstriction
constriction of blood vessels near skin surface
less blood flows close to skin surface
less heat loss to the surroundings
why must blood glucose concentrations be controlled
if blood glucose concentration rise too high the body risks dehydration
if blood glucose become to low the rate of cellular respiration decreases
which organ is responsible for the control of blood glucose concentrations
pancreas
how is blood glucose concentration controlled
blood glucose is controlled by insulin ( a hormone) which is secreted by the blood
what does insulin do to blood glucose levels
it causes them to decrease back to a normal level
glucose os converted into glycogen, a storage molecule
insulin causes liver and muscle cells to increase their uptake of glucose from the blood
what does glucagon do to blood glucose levels
it causes them to rise back to normal
it causes a breakdown of glycogen to glucose in the liver
glucose is released into the blood
what is the control of blood glucose concentration an example of
negative feedback
what happens when blood glucose concentrations come to high
blood glucose concentration increases above a set point
pancreas secretes insulin and stops producing glucagon
liver cells convert glucose to glycogen which is stored
blood glucose concentration decreases, returning to normal level
describe what happens when blood glucose levels become too low
blood glucose concentration decreases below a set point
pancreas secretes glucagon and stops producing insulin
liver cells convert glycogen into glucose which is released into blood
blood glucose concentration increases, returning to norma level
what is diabetes
a condition where the homeostatic control of blood glucose levels stop working
what are the two types of diabetes
type 1 diabetes
type 2 diabetes
what causes type one diabetes
the immune system attacks and destroys insulin producing cells
therefore the pancreas does not produce enough insulin
how is type one diabetes treated
daily insulin injections at meal times
managing diet (limit intake of refined sugars)
regularly testing blood glucose levels
what is the cause of type 2 diabetes
person develops insulin resistance (often due to obesity)
how is type 2 diabetes treated
managing diet (limit intake of sugars)
regular exercise
drugs e.g metformin
what is a drug
describe the effects of alcohol on the body
decreased reaction time
addictive
causes liver damage, cardiovascular disease
what is negative feedback
negative feedback is a corrective mechanism that allows only small fluctuations around a set point.
e.g. the control of blood glucose concentration
what is a sense organ
a group of receptor cels that detect specific stimuli and send information to the central nervous system along neurones.
what is the process of the reflex arc
receptor cells pick up a harmful stimulus
stimulation of the. pain receptor
impulses travel along the sensory neurone
impulses are passed along a relay neurone via a synapse
impulses travel along a motor neurone via a synapse
when impulses reach the effector (muscle) the contract
what are the characteristics of the reflex arc
rapid
automatic
protective
