Human Digestive

System

Amina Bouhitem

The structure of the digestive system

Major food contents

Carbohydrates: The digestion of Carbohydrates occurs

by chemical reactions which break the big molecules into Glucose.

using three different enzymes, Salivary amylase, Pancreatic amylase and Maltase.

Protein: are polymer chains of amino acids. Are broken down to provide amino

acids, using three enzymes, Pepsin, Trypsin and peptidases.

Lipids: the body uses the fat as a fuel Have several forms.ieSaturated, unsaturated Broken down to Fatty Acids and Glycerol

by using Lipase enzyme.

Nucleic acid: biological molecule which is essential for life Broken down by Nuclease and

Nucleosides enzymes to provide nucleotides.

http://www.youtube.com/watch?v=tTZUBOhm6xw&feature=related

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The function of organs in food digestion

Mouth: Chews the food and breaks it to small pieces Early digestion Salivary Glands- Salivary Amylase

Esophagus Located in throat near Trachea Receives food from mouth, Swallows it by muscular contraction. Delivers the food to stomach

Stomach Big muscular organ which churns up the food and contains it while mixing with several enzymes. Protects it’s wall against acid by lining with mucous. Protein is broken in stomach

Pancreas

Secretes digestive enzymes into duodenum These enzymes include Pancreatic

Amylase, Trypsin, Nuclease, Nucleosidases and Lypase.

In order to digest all the four major food contents

Liver Processes the nutrients absorbed by

small intestine. Secretes ‘Bile’ which helps digesting fat. Makes various Chemicals needed for the

body from the absorbed nutrients.

Small Intestine Is 22-foot long muscular tube that breaks down food using enzymes released by pancreas,

bile and liver Peristalsis responsible for the movement

of food Absorption of nutrients takes place in the

small intestine

Absorption:

The soluble products are first taken up by various mechanisms into the epithelial cells that line the gut.

These epithelial cells then load the various absorbed molecules into the blood stream.

Assimilation:

The soluble products of digestion are then transported to the various tissues by the circulatory system.

The cells of the tissues then absorb the molecules for use within this tissues

The structure of the villus

Blood supply in the villus which absorb the end products of digestion from the epithelial cells

The lacteals (green) that receive the lipoproteins before transporting them to the circulatory system.

Muscular walls that maintain the movement of chyme by peristalsis.

Blood

Large Intestine Is 6 foot long tube connects the small intestine to the rectum is specialized organ for processing waste by absorbing water. Changes contents from liquid to semi-

solid state.

Rectum and Anus Rectum is an 8-inch chamber. It receives feces from large intestine and holds it until excreted by Anus which is

2- inch long organ consisting of pelvic floor muscles. Anus is the last part if digestive tract.

Keep your digestive system in good shape by eating balanced meals with a lot of fruits and vegetables

Questions?

References:  

http://click4biology.info/c4b/6/hum6.1.htm#four

http://www.cchs.net/health/health-info/docs/1600/1699.asp?index=7041

http://www.yteach.co.uk/page.php/resources/view_all?id=amino_acid_aminopeptidases_bile_salts_carbohydrate_digestion_carboxyl_group_(COOH)_of_amino_acid_carboxypeptidase_casein_caseinogen_chymosin_chymotrypsin_dipeptide_disaccharidases_page_4