detail about human digestive system

1. DIGESTIVE SYSTEM
DR.TEHREEM FATIMA

3. INTRODUCTION:
• The digestive system consists of gastrointestinal tract.
• The accessory organ of digestion is Tongue, salivary glands, pancreas, liver and
gallbladder.
• It helps to breakdown complex food into smaller and simplest form.
• The process of digestion consists of three stages
1. Cephalic phase
2. Gastric phase
3. Intestinal phase

4. 1. CEPHALIC PHASE:
• Cephalic means is ( related to head).
• The first phase of digestive system beings with the secretions from gastric glands.
• In response to the sight and smell of food.
• It includes the mechanical breakdown of food by chewing, and the chemical breakdown by
digestive enzymes, that take place in mouth.
• Saliva consists of digestive enzymes amylase and lingual lipase, secreted by the salivary and
serous glands on the tongue.
• The chewing is the mechanical process that mix the saliva with food.
• This produce a bolus which is swallowed down the esophagus to enter the stomach.

6. 2. GASTRIC PHASE:
• The second stage of digestive begins in the stomach
with gastric phase.
• Here the food is further broken down by mixing
with gastric acid( present in stomach).
• And then passes into the duodenum, the first part
of the small intestine.
• The digestive enzymes including gastrin converts the
food into thick semiliquid substance called chyme.

7. 3. INTESTINAL PHASE:
• It begins in the duodenum.
• Here the food partially digested and mixed with the number of enzymes produced by the
pancreas like bile juice etc.
• Digestion is helped by the chewing of food carried out by the muscle of mastication, the
tongue, the teeth and segmentation.
• Gastric acid and the production of mucus in the stomach, are essential for the continuation
of digestion.
• Peristalsis is the rhythmic contraction of the muscle that begins in the esophagus and
continues along the wall of the stomach and the rest of the gastrointestinal tract.

8. Continue…..
• Chyme which when fully broken down in the
small intestine is absorbed as chyle into the
lymphatic system.
• The indigestive food goes into the large intestine
where no digestion and absorption take place.
• Just water and some minerals are reabsorbed back
into the blood in the colon of the large intestine.
• The waste products of digestion (feces) are
defecated from the rectum via the anus.

9. THANK YOU