Outline and explain the various homeostatic functions of the liver in mammals.

-
Deamination;  process  of  removal  of  an  amino  group  from  an  amino  acid  molecule;  the  process gets  rid  of  excess  amino  acids  in  the  body;  as  the  body  is  not  able  to  store  them;  the  amino  group enters  the  ornithine  cycle;  where  it  is  combined  with  carbon  (IV)  oxide  to  form  urea;  which  is excreted  in  urine  through  the  kidney;  Heat  production;  many  metabolic  activities  take  place  in the  liver;  releasing  heat  energy;  that  is  distributed  by  the  blood  to  other  parts  of  the  body;  this helps  in  thermoregulation;  Storage  of  vitamins  and  mineral  salts;  Vitamins  A,  B,  D,  E  and  K;  are stored  in  the  liver;  worn-out  red  blood  cells,  are  broken  down  to  yield  iron;  which  is  stored  in  the liver  in  form  of  ferritin;  this  is  used  later  in  case  of  shortage;  Formation  of  red  blood  cells;  occurs in  the  liver  of  the  foetus;  the  liver  also  breaks  down  old/exhausted  red  blood  cells;  leading  to formation  of  more  in  the  bone  marrow  to  replace  the  worn-out  cells;  to  enhance  oxygen  and carbon  (IV)  oxide  distribution;  Regulation  of  blood  sugar  level;  liver  cells  convert  excess glucose  into  glycogen  and  fats  under  the  influence  of  insulin  hormone;  the  stored  glycogen  is however  converted  back  to  glucose;  when  glucose  levels  are  low;  by  the  liver  cells;  under  the influence  of  glucagon  hormone;  Regulation  of  plasma  proteins;  plasma  proteins  such  as prothrombin  and  fibrinogen  are  manufactured  in  the  liver  using  the  amino  acids  found  in  the liver;  they  play  a  major  role  in  blood  clotting;  that  prevents  excessive  blood  loss  and  infection  at the  injured  area;  other  plasma  proteins  produced  by  the  liver  such  as  serum  and  albumen; contribute  to  the  maintenance  of  osmotic  pressure  in  the  body;  non-essential  amino  acids  are  also synthesized  by  the  liver;  for  use  by  the  body;  Storage  of  blood;  the  liver  is  highly  vascularised; hence  it  is  capable  of  holding  a  large  volume  of  blood  when  the  blood  vessels  dilate  during  hot conditions;  when  the  temperatures  are  low,  the  blood  vessels  constrict  under  the  influence  of  the endocrine  and  nervous  systems;  hence  less  blood  is  stored  in  the  liver;  this  contributes  to thermoregulation;  Detoxification;  this  is  the  process  where  harmful  compounds  such  as  drugs and  poisons;  are  converted  to  less  toxic  compounds  in  the  liver;  toxicity  is  caused  by  medication, drugs  and  microorganisms;  the  toxic  compounds  are  later  excreted  in  urine;  detoxification prevents  the  accumulation  of  toxins  in  body  cells;  which  could  lead  to  death  or  malfunctioning  of the  body  cells;  Max.  20  mks 

Comments

Post a Comment

Popular posts from this blog

DESCRIBE THE ADAPTATIONS OF THE ILEUM TO ITS FUNCTION (20 MARKS)

-
Has secretory glands/crypts of lieberkuhn which secretes enzymes (maltase/sucrase/lactase/peptidase/lipase to complete digestion of sugars/proteins/lipids. Goblet cells secrete mucus which allows for smooth movement of food and protect wall of ileum from action of digestive enzymes Very long to provide large surface area for absorption. Highly folded/coiled to slow movement of food to allow more time for digestion/absorption/ and to increase surface area for absorption. Has numerous villi which increase surface area for absorption/microvilli which further increase surface area for absorption. Ileum wall/villi have thin epithelium which is only one cell thick to reduce distance over which digested food has to diffuse. Villi are highly vascularised/have a rich network of blood capillaries for rapid transport from small intestines and maintain a steep concentration gradient for rapid absorption. Villi have lacteals for absorption of fatty acids and glycerol Cells of ileum wall h...
Read more

KCSE 2010 Q8. Describe how a finned fish such as Tilapia moves in water. (20 marks)

-
The following describes how  a finned fish such as Tilapia moves in water . v       Water is denser than air. The density of water supports fish and provides a medium in which it swims. v       It has a streamlined body; reducing resistance, thus easily swims in the water. v       The scales overlap pointing backwards allowing water to pass over the fish without obstruction. Mucus is also secreted over the scales reducing friction during movement. v       They have a flexible backbone onto which segments of muscle blocks, myotomes, are attached. The muscles contract and relax bringing about undulating movements. v       The fish have fins that help in steering and balancing fish during swimming. v       The pectoral and pelvic fins are paired. They are used for braking, steering and v   ...
Read more

Explain how structures of the human ear are adapted to their functions. (20 marks)

-
Image
The pinna;- is funnel shaped to trap sound waves; cartilaginous to maintain the funnel shape; collects and directs sound waves into the external auditory meatus ear; The external auditory canal; - a tube connected to the pinna that directs sound waves from the pinna to the eardrum lining the auditory canal; has hair that trap foreign particles; The canal contains wax-secreting cells; and hair which traps dust particles; and pathogenic bacteria hence prevent them from getting into the ear; The eardrum; - has a thin tough membrane; that easily vibrates when hit by sound waves; transferring them into vibrations. The ear ossiscles; - they act like a layer and they easily move forward and backward to amplify sound vibrations that hit them; The suspensory ligaments; - suspends the ear ossicles and prevents excessive vibration that would otherwise damage the inner parts of the ear; The eustachian tube - it connects the middle ear with the pharynx; and it equalises air pressure between...
Read more