Digestive system helps in the breakdown and conversion of the complex biomolecules of food into the simple substances. DIGESTION ALIMENTARY CANAL

1. ANATOMY OF HUMAN DIGESTIVE
SYSTEM
SUBMITTED BY:
Shriya Sangral
M.Sc. Human Genetics
Institution of Human Genetics, University of Jammu

2. LEARNING OBJECTIVE
• To impart the anatomy of human digestive system.
• To demonstrate the functions of various enzymes involved in the digestion
process
• To highlight the different functions and the mechanism of the digestive system.
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3. CONTENT
Introduction
Alimentary Canal
Accessory organs
References
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4. DIGESTIVE SYSTEM
It Consist of two part:
• Alimentary Canal: Consist of 4 layers
Serosa
Muscularies
Sub mucosal
Mucosa
• Accessory organs
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5. ALIMENTARY CANAL
Alimentary Canal:
• Also known as gastrointestinal tract (GI Tract)
• 5-7 meter long
• Muscular walls
• It consist of: mouth, buccal cavity, pharynx, oesophagus, stomach, small intestine,
large intestine, anus
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6. ACCESSORY ORGANS
Accessory organs:
• Salivary gland
• Gastric gland
• Pancreas
• Liver
• Gallbladder
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7. MOUTH
Structure:
• Transverse slit
• Bounded by two soft movable lips
• Lead to buccal cavity
Function:
• Ingestion of food into the buccal cavity
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8. BUCCAL CAVITY
Also known as oral cavity and contain salivary gland.
Structure: Consist of no. of teeth and a muscular tongue
Teeth: Fixed in socket of jawbones, such teeth are thecodont
There are two sets of teeth during lifespan i.e. diphyodont
Deciduous (temporary milk)
Permanent teeth
32 permanent teeth in an adult human
Incisors (I) Premolar (PM)
Canine (C) Molar (M)
Made up of Enamel (mineralized tissue, hard, shinny layer of calcified tissue)
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9. BUCCAL CAVITY
Tongue: Freely movable, muscular organ
Attached to the floor of oral cavity by Frenulum
Papillae (contain taste buds) present on its upper surface
Salivary gland: Produce saliva
Saliva contain:
Mucus
Enzymes (salivary amylase & lysozyme)
Electrolytes
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10. BUCCAL CAVITY
Reaction:
Starch Maltose
Function:
Mastication of food
Lubrication of food
Facilitation of swallowing
Starch hydrolysis (30%)
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Salivary amylase
pH 6.8
10

11. PHARYNX AND OESOPHAGUS
Structure:
Pharynx: 12cm long tube
Oesophagus: 25cm long tube
Function:
Help in the passage of food.
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12. STOMACH
Structure:
• 30cm long and 15cm wide
• 4 regions:
Cardiac region (broad)
Fundus (often contain air/gas)
Body
Pyloric region (narrow)
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13. STOMACH
Gastric gland:
• Present in the mucosa layer
• Produce gastric juice
• Contain 3 type of cells
Mucus neckcell: secrete mucus
Peptic cell: secrete proenzyme (pepsinogen)
Parietal cell: secrete HCl and intrinsic factor
• Small amount of lipases also secreted
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14. STOMACH
Reaction:
Pepsinogen Pepsin
Protein Peptide
Function:
Store food for 4-5 hours
Absorption of water, simple sugar, alcohol
Production of HCl, enzymes, mucus, bicarbonate ions
Protein hydrolysis
Lubrication
Digestive System By: Shriya Sangral
HCl
pH 1.8
(inactive) (active)
Pepsin
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15. SMALL INTESTINE
Structure:
• 6m long and narrow tube
• Longest part of alimentary canal
• Comprises of 3 parts
Duodenum: 25-38cm long
Jejunum: 2.5m long
Ileum:2-4m long
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16. SMALL INTESTINE
Bile and Pancreatic juice release into the stomach through hepatic-pancreatic duct.
• Bile Juice:
Contain cholesterol, bile salts
Contain bile pigments and phospholipids
Help in emulsification of fats.
Don’t contain any enzyme
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17. SMALL INTESTINE
• Pancreatic juice: It contain various enzymes (inactive)
Trypsinogen
Amylase
Lipases
Nucleases
Chymotrypsinogen
Procarboxypeptidases
• Intestinal juice: Contain various enzymes
Disaccharides
Dipeptidases
Lipases
Nucleosidases
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18. SMALL INTESTINE
Reactions:
• Breakdown of Proteins:
Trypsinogen Trypsin
Chymotrypsinogen Chymotrypsin
Procarboxypeptidases carboxypeptidases
Protein Dipeptides Amino acids
Protein Dipeptides + Amino acids
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enterokinases
Trypsin dipeptidases
trypsin
trypsin
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chymotrypsin/ carboxypeptidases

19. SMALL INTESTINE
• Breakdown of Starch:
Starch Maltose 2(Glucose)
• Breakdown of fats:
Fats Triglycerides Diglycerides Monoglycerides
• Breakdown of nucleic acid:
Nucleic acid Nucleotides Nucleosides
Nucleosides Sugar + Bases
Digestive System By: Shriya Sangral
amylases
lipases
maltase
lipases lipases
nucleases nucleotidases
nucleosidases
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20. SMALL INTESTINE
Function:
• Muscularies layer show various movement.
• Mixing of food
• Facilitates digestion
• Secretion of intestinal juice
• Bile and pancreatic juices released into it through Hepatic-pancreatic duct
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21. LARGE INTESTINE
Structure:
• 1.5m long
• Wider than small intestine
• It has 3 regions:
Caecum
Colon
Rectum
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22. LARGE INTESTINE
Function:
• Mucus secretion
• Absorption of water
• Absorption of minerals
• Absorption of certain drugs
• Temporary storage of undigested food
Anus: Removal of unabsorbed/waste product through anus.
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23. PANCREAS
• Compound elongated organ
• Exocrine portion secretes alkaline
pancreatic juice and enzymes
• Endocrine portion secretes hormones,
insulin, glycogen
• Secrete Mucus and bicarbonate that
protect intestinal mucosa from acid and
provide pH 7.8
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24. LIVER AND GALLBLADDER
Liver:
• Largest gland
• About 1.6kg in weight
• Secretes bile juice by hepatic cells
Gallbladder:
• Thin muscular sac
• Store bile juice
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25. REFERENCES
• Principles of anatomy and physiology, 12th edition by Gerard J. Tortora and Bryan
Derrickson
• Text book of biology by P.S. Dhami, Dr. G. Chopra, Dr. H.N. Srivastava
• Human physiology by Dr. Neela Bakore
• Cdn.Britannica.com
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26. THANK YOU
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