Describe how various parts of the alimentary canal/ digestive system are adapted/ suited to their functions.

a) Mouth
-Has teeth; for chewing / grinding food to increase surface area for digestion by enzymes;
-Has salivary glands; which secrete saliva which lubricate, soften, moisten, dissolve food and provide alkaline medium for action of enzymes;
-Saliva contains salivary amylase/ ptyalin; which digest starch into maltose;
-It has muscular tongue to mix food with saliva and roll food into boluses and pushes them to the back of the mouth (for swallowing);
b)Oesophagus/ gullet
-It is made up of smooth muscles with contract and relax; to facilitate peristalsis;
-Inner lining has goblet cells that secrete mucus; to lubricate food hence facilitate smooth movement of food/ boluses;
c)Stomach
-It has muscular wall which contract and relax; to facilitate churning of food into chime;
-The stomach lining has goblet cells that secrete mucus; to protect them against auto digestion by enzymes;
-The inner lining has gastric glands that secrete gastric juice; containing pepsin and rennin for digestion of proteins; hydrochloric acid to provide acidic medium for action of enzymes and kill bacteria;
-It has cardiac sphincter; to allow food into the stomach;
-It has pyloric sphincter; to retain food in the stomach for digestion;
d)Duodenum.
-It has Brunner’s gland on its walls to secrete mucus; for lubrication of food;
-It has crypts of Liberkuhn whose cells secrete digestive enzymes; for digestion of food;
-It is connected to the pancreas and the liver; to supply pancreatic juice and bile respectively; bile emulsifies fats/ lipids; and neutralizes the acid from the stomach; pancreatic juice contains enzymes; for digestion of food;
e)Ileum
-The ileum is long; to increase the surface area for digestion and absorption of food;
-They are highly coiled/ folded; to slow down movement of food to allow more time for digestion and absorption of digested food substances.
-Inner lining has numerous villi and micro-villi; to increase the surface area for digestion and absorption of food substances;
-Their walls have glands (crypts of Liberkurn) that secrete intestinal juice; which contains enzymes for digestion of food;
-Inner lining has goblet cells that secrete mucus; to lubricate food and protect their walls against digestion by enzymes; and lubrication of food;
-It is narrow/ has narrow lumen; to bring food into contact with intestinal walls/ blood vessels rapid/ faster absorption of food substances;
-The walls have smooth muscles which contract and relax; to facilitate peristalsis;
-It is highly vascularized/well supplied with blood capillaries; to create a steep/high concentration gradient hence faster diffusion of digested food/ for rapid and efficient of removal of absorbed products;
-Has lacteal vessels; for absorption of fatty acids and glycerol;
-Has thin epithelium; to reduce the distance travelled by digested food hence faster absorption;
-Has numerous mitochondria; to provide energy for absorption of food;
f)Colon
-Its walls consists of smooth muscles which contract and relax; to facilitate peristalsis;
-Inner lining has goblet cells which secrete mucus; for lubrication;
-Inner membrane is highly folded; to increase surface area for absorption of water, mineral salts and attachment of micro-organisms;
g)Rectum
-Has goblet cells which secrete mucus; for lubrication and to help in defecation;
h)Anus.
-Has muscular sphincter; to control defecation;