homeostasis Flashcards
what is homeostasis?
maintance of a constant state.
what is a stimulus?
a control system, as having a sensor that montiors the fcator being controlled/
what is a corrective mechanism?
brings about changes resulting in regulation of this factor.
what is a negative feedback mechanism?
stops the corrective mechanism and prevents over correction.
how does the body control corrective mechanisms?
for glucose, control centre is in pancreas. pancreas monitors glucose level,if low glucose, then releses hormones glucagon.if too much glucose detcted in pancreas then releases hormone insulin.
how can we maintain a constant internal environment?
1) detect a change
2) coordinate a response
3) reverse a change
what is the effector? in glucose if too little
The effector for this feedback loop is the liver.
Glucagon stimulates the liver to breakdown its store
of glycogen into glucose, which is then released
into the blood to increase the level of blood glucose.
what is the effector ? in gluscose too much
Insulin does the opposite and stimulates the liver
to start converting glucose to glycogen and storing
it so the level in the blood goes down.
where does osmoregulation occur?
in the nephron of the medula.
what are nephrons?
they are long tubules, surrounded by capillaries.
what is the afferant arteriole?
the affereant arteriole branches in to many small capillaries, forming the glomerlus.
what is the function of the nephron?
filter the waste out of the blood, and selectively reabsorb the useful substances back in to the blood.
what will urine contain?
water, dissolved salts, urea, other small hormones e.g vitmin.
what does the urine NOT contain, and why?
proteins and blood cells- too large to be filtered out of blood, so remains.
glucose- is useful so all is absorbed by active transpirt at selective reabsorption stage in PCT.
how filtering and reabsorption occurs?- STAGE 1?…
ultrafiltration- due to high hydrostatic pressure , water and small molecules are forced out of the glomerlus in to bowmans capsule.
