Digestion The process whereby large food molecules are broken down into smaller, soluble, diffusible, simpler forms that can be absorbed into our body. Physical-Mechanical breakdown of food into smaller particle Chemical- Enzymatic hydrolysis of food substances
Mouth & Buccal CavityMouthThe opening that food enters & leads to thebuccal cavity.Buccal CavityTongue- Mixes food with saliva (Amylase) - Rolls food into Bolus - Pushes food down the PharynxTeeth- Chews food into smaller pieces for enzymatic reactions. (mastication)
Oesophagus ( gullet) Consist of the inner circular muscles and outer longitudinal muscles. Does not digest food. It is a muscular tube that pushes food down the body through peristalsis. Peristalsis is the strong and rhythmic movement. The inner circular muscles relaxes and the outer longitudinal muscles contracts, the lumen widens for food to enter. When the inner circular muscles contracts and the outer longitudinal muscles relaxes, the food is pushed forward.
Stomach A distensible, muscular bag with thick and well- developed muscular walls. It creates powerful muscular contractions called churning, which mixes food with gastric juices to form chyme. Gastric juice : Hydrochloric acid Protease(Digest proteins) Acidic environment: To kill germs & pasticides. Provide an optimum environment for protein digestion (Ph 1-2.5). Stop action of salivary amylase
Small intestine 6m long connected with liver and pancreas. Consists of : U-shaped duodenum Jejunum ileum Bile Pancreatic juice : Pancreatic amylase, Pancreatic lipase, protease Intestinal juice: Peptidase,maltase,lipase Mucus is produced.
Villus Finger-like structures which increases surface area for digestion
Liver Produces a yellowish-green fluid called bile. Bile does not contain enzymes but helps in fat digestions through the process of emulsification. Emulsification is the breaking down of fats molecules into smaller droplets to increase surface area for fat digestion. Bile is temporarily stored in gall bladder.
Pancreas Situated between stomach and small intestine. Secretes pancreatic juice (alkaline) containing amylase, protease. Alkaline juice neutralizes the acid in the food from stomach.
Large intestine About 1.5 m long Absorbs remaining water and minerals salts.
Rectum Near solid waste called Faeces is temporarily stored in the rectum.
Anus Faeces is forced out of the gut through anus. (Egestion) Faeces contains mainly digested food and unabsorbed material. Faeces contains dead bacterial, cellulose, mucus, cholestrol,water.