Human Nutrition

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1) When circular muscles contract longtitudinal muscles relax 2) When circular muscles relax longtitudinal muscles relax

2) Wall Dillates = Food can enter

1) Wall Constricts = Food Pushed

Hepatic portal vein

Breakdown large molecules in food into small soluble molecules to be absorbed.

Increse surface area to volume ratio so that digestive enzymes can act on food more efficiently.

Human Nutrition

Organs and glands associated with the gut

Pancreas

Produce hormones

Insulin and Glucagon

Produce pancratic juice.

Gall Bladder

Temporarily store bile

Liver

Detoxification of alcohol

Alcohol dehydrogenase break down alcohol to form acetaldehyde which may be used in cellular respiration.

Deamination of amino acids

Protein Synthesis

Break down haemoglabin in red blood cells

Regulate blood glucose concentration

Aid in fat digestion by secreting bile

Bile emulsifies fats

Alimentary Canal

Anus

Faces are egeested through the anus.

Large intestine

Colon Rectum

-Water and mineral salts are absorbed from undigested food material. -Faces are stored temporarily in the rectum.

Small Intestine

Ileum

- The small intestine is long to provide sufficient time for absorption. - The intestinal wall and the villi have many capillaries to carry away the absorbed food substances. In each villus is a lacteal or lymphatic capillary surrounded by blood capillaries. This continual transport of digested food substances maintains the concentration gradient for the absorption of digested food substances.

- The inner wall of the small intestine is highly folded. - The folds are lined with microscopic, finger-like projection called villi. - The epithelial cells of the villi, in turn, have numerous microvilli. - The epithelium of the villi is one cell thick.

Increases surface area to volume ratio for absorption

Digested food are absorbed by the villi of the small intestine.

Glycerol and fatty acids diffuse into the epithelium, where they recombine to formfat globules and enter lymphatic capillaries.

Glucose and amino acids are absorbed by diffusion/active transport into the blood capillaries.

Duodenum

Physical Digeation

Bile salts emulsify fats into tiny droplets.

Chemical Digestion

Pancreas secrete pancreatic juice - Action of amylase : starch ------>maltose - Action of trypsin : starch ------>maltose - Action of lipase : fats ------>fatty acids and glycerol

Intestinal glands secrete intestinal juice - Action of enterokinase : trypsinogen ------> trypsin - Action of maltase : maltose ------>glucose - Action of lactase : lactose ------> glucose and galactose - Action of sucrase : sucrose ------> glucose and fructose - Action of erepsin : polypeptides ------> amino acids - Action of lipase : fats ------> fatty acids and glycerol

Stomach

Chemical Digestion

Action of rennin : soluble caseinogen ------> insoluble casein

Action of pepsin : proteins ------> polypeptides

Physical Digestion

Peristalsis mixes the food with the gastric juice

Oesophagus

Food passes down via peristalsis by antagonistic muscles

Longitudinal muscles (outer layer)

Circular muscles (inner layer)

Mouth

Chemical Digestion

Action of salivary amylase : strach ------> maltose

Physical Digestion

2) Tongue mix food and rolls food bvvinto small round masses (boli)

1) Chewing break up the food.