digestion.ppt my own slides

DigestionDone by: Ooi huiying

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 the buccal 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.

Enzymes & their reactantsEnzymes reaction

Protease Proteins- Amino acids

Lipase Fats- glycerol + fatty acids

Amylase Starch- maltose

Maltase Maltose- glucose

Enzymes. Pancreatic juice : Amylase, maltose

protease, lipase. Intestinal juice : Maltose, protease,

lipase