Explain the role of the following hormones during homeostasis.

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 a)  Antidiuretic  Hormone  (ADH) Secreted  by  the  (posterior  lobe/end)  pituitary  gland;  in  response  to  an  increase  in  the osmotic  pressure  of  blood;  the  hormone  stimulates  the  distal  convoluted  tubules  and  the collecting  ducts;  to  increase  their  permeability  to  water;  this  increases  the  reabsorption  of water  into  the  bloodstream;  concentrated  and  less  urine  is  excreted;  when  the  osmotic pressure  decreases,  less  or  no  hormone  is  produced;  hence  the  tubules  become  impermeable to  water;  less  water  is  reabsorbed  into  the  bloodstream;  hence  more  dilute  urine  is  excreted; fluctuations  in  the  osmotic  pressure  is  detected  by  the  hypothalamus;

 b)  Insulin
 Secreted  by  the  pancrease;  in  response  to  a  rise  in  blood  sugar  level;  it  stimulates  liver  cells to  convert  the  excess  glucose  into  glycogen  and  fats  for  storage  in  the  liver  and  muscle cells;  increases  the  oxidation  of  glucose  in  respiration  to  yield  water  energy  and  carbon (IV)  oxide/increases  metabolism  in  the  body;  this  leads  to  a  fall  in  blood  glucose  to  normal level;

 c)  Glucagon
 Secreted  by  the  pancrease;  in  response  to  a  decline  in  blood  glucose  level;  it  stimulates liver  cells  to  convert  the  stored  glycogen  and  fats  back  to  glucose;  stimulates  the conversion  of  amino  acids  to  glucose;  and  stops  the  oxidation  of  glucose  in  the  body  cells; the  glucose  formed  is  released  to  the  bloodsteream  causing  a  rise  of  blood  glucose  level  to normal;  Max.  20  mks 

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