Brief presentation on Digestive System

1. Digestive System

2. What is digestive system?
When two or more organs act together for receiving, breaking
down and absorption of food materials is known as the
digestive system.
Digestive System can be divide into 2 parts:
1. Digestive Tract / Alimentary Tract
2. Digestive Glands

3. Parts of digestive system

4. Parts of Digestive System
• Mouth & Mouth cavity
• Pharynx
• Esophagus
• Stomach
• Duodenum
• Jejunum Small Intestine
• Ileum
• Ascending Colon
• Transverse Colon Large Intestine
• Descending Colon
• Sigmoid Colon
• Rectum
• Anal canal
• Anus

5. Accessory organs of
digestive system
•Tongue
•Teeth
•Salivary glands
•Liver
•Gall-bladder
•Pancreas
Parts of Digestive System

6. Passage of food through Digestive Tract
Sigmoid
Colon
The Mouth
Pancreas

7. What is Digestion?
The process by which food is broken down into simple chemical compounds that
can be absorbed and used as nutrients or eliminated by the body.
 Proteins Amino acids (used to make proteins)
 Carbohydrates Simple sugars/glucose (used by the mitochondria for
energy)
Fatty acids & glycerol (used for cell membranes, energy
 Lipids
production)

8. Stomach
 J-shaped organ.
 pH: 1.5 to 3.5 (Acidic environment)
 Food is mixed with gastric juices
(hydrochloric acid and enzymes)
 HCL helps break down food and kills
bacteria that came along with the
food.
 Parietal cell secrets Hydrochloric
acid.

9. Function of Stomach
The stomach has five major functions:
a. Temporary food storage.
b. Control the rate at which food enters the duodenum.
c. Acid secretion and antibacterial action.
d. Fluidization of stomach contents.
e. Preliminary digestion of protein & fat by pepsin &
gastric lipase respectively.

10. What is parietal cell?
•Parietal cell is a special cell of stomach, it present in
fundus and body of the stomach. It secrets Hydrochloric
Acid.
What is the function of HCl
1. HCl dissolves the foods we eat.
2. Stops the action of ptyalin.
3. HCl kills any pathogens, present in foods we eat.
4. HCl activates pepsinogen (a pro-enzyme from Chief cell)
into the enzyme pepsin, Pepsin breaks up protein to
form peptides.
5. Regulates opening closing of pyloric sphincter.

11. Acid secretion increased by
a. Acetylcholine
b. Gastrin
c. Histamine (H2) receptor
d. Local and central nervous control
e. Gastric irritation – By ethanol, vinegar, bile salts, aspirin, NSAIDs etc.

12. Self defense mechanism of stomach and
duodenum from HCl
1.By Mucin secretion
2.By bicarbonate ion secretion
3.More regeneration power
4.Increase blood supply
5.Tight junction between the adjacent cells

13. Mechanism of HCl Acid Secretion
The hydrogen ion concentration in parietal cell
secretions is roughly 3 million fold higher than in
blood, and chloride is secreted against both
concentration and electric gradient. Thus, the ability
of the parietal cell to secrete acid is dependent on
active transport.
The key player in acid secretion is a H+/K+ ATPase or
"proton pump" located in the cannalicular
membrane of parietal cell.
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14. Liver
It is the largest gland (weight-1.5 kg) in the body consists
of 2 lobe- right & left.
Functions of Liver:
1. Metabolic-
• Break down the stored fat and amino acid.
• Detoxification of drugs & poisons
• Synthesis of plasma proteins, vitamin A from carotene, prothrombin &
fibrinogen
• Manufacture of heparin, antibodies, antitoxins etc
• Conversion of excess carbohydrate into fat.
2. Storage- Vitamin (A & D), Iron & Glucose as glycogen.
3. Secretary- Bile

15. Small Intestine
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The small intestine is a gradually narrowing tube, about
7 meters long.
It has 3 parts
1. Duodenum - 25 cm
2. Jejunum - 2.5 meters
3. Ileum - 4 meters

16. Function of Small Intestine
The functions of small intestine are digestion and absorption of
food.
1. Digestion is carried out by pancreatic juice, bile and intestinal
juice. The pancreatic juice consists of water, alkaline salts.
Amylase, which turns starch, cooked, and uncooked into, malt
sugar (maltose).
Lipase, which splits fat into fatty acids and glycerol, after that the
bile has emulsified the fat.
2. Absorption occurs from the villi and microvilli of small intestine.

17. Large Intestine
The large intestine is a tube leading from the small intestine to the
external skin and much wider than the small intestine. It is about
1.5m long and is continuous above with the ileum and ends at
rectum.
It has following parts:
1. Cecum- 6cm
2. Vermiform appendix-
(2-20cm) a small finger like
projection from cecum.
3. Ascending Colon- 25cm
4. Transverse colon- 50cm
5. Descending colon- 35cm
6. Sigmoid colon- 25cm

18. Functions of Large intestines
Large intestine has 4 important functions:
1. Absorption of water (so feces excreted as semisolid).
2. Excrete waste products.
3. Bacteria in large intestine ferment food producing the typical
odor of stools.
4. Normal bacterial flora, which helps synthesis of some
important vitamins.

19. Rectum: A muscular bag that contains feces.
Anal canal and Anus: A canal like extension that helps to expel out
the feces from rectum and finally exit through anus (A small
opening).
Rectum & Anal canal

20. Pancreas
It is a mixed type of gland consisting both exocrine and endocrine
gland.
Function of Pancreas:
Exocrine gland secretes pancreatic juice that contains-
1. Trypsinogen- converted into trypsin. This trypsin converts the
proteins & peptones into amino acid.
2. Amylase - turns starch into maltose.
3. Lipase - splits fat into fatty acid and glycerol.
Endocrine gland secretes hormones, namely-
1. Insulin - lowers blood glucose level.
2. Glucagon - raises blood glucose level.

21. The Alimentary tract deals with food in
four stages
1. Ingestion: Intake of food.
2. Digestion: Begins in the mouth but mainly carried out in the
stomach and small intestine.
3. Absorption: Passage of end product of digestion through the
wall of intestine into blood and lymphatic system.
4. Excretion: Removal of non-digested food particles as feces
through anus.

22. What is Peristalsis?
Peristalsis – Wavelike movement (contraction followed by
relaxation) of smooth muscle of GI tract to push food
particles forward.

23. Diseases of Digestive System

24. Diseases of Digestive System
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25. Diseases of Digestive System
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26. Common Diseases of Digestive System
 Hyperacidity: A set of symptoms caused by an imbalance between
the acid secreting mechanism. Symptoms are abdominal pain,
discomfort, bloating, nausea, dysphagia (difficulty swallowing)
etc.
 Ulcer: Ulcer is a lesion on the mucous membrane of the stomach.
Symptoms: Burning stomach pain, Feeling of fullness, bloating or
belching, Fatty food intolerance, Heartburn, Nausea.
-Gastric ulcer: Develop inside the stomach.
-Duodenal ulcer: Develop in the duodenum
-Peptic ulcer: Gastric ulcer + Duodenal ulcer
-Esophageal ulcer: Develop inside the esophagus.

27. Common Diseases of Digestive System
 Reflux esophagitis/ GERD: Backwards movement of food and
acid from stomach to esophagus. It includes heartburn,
esophagitis, chest pain, dysphagia, belching etc.
 Zollinger-Ellision Syndrome: A rare condition in which one or
more tumors form in your pancreas or the upper part of your
small intestine (duodenum). Symptoms: Similar to ulcer. Other
symptoms- Diarrhea, vomiting, bloating.
 Hepatitis: Inflammation of liver. Occurs as a secondary result of
medications, drugs, toxins, and alcohol. Common Symptoms
are: fatigue, flu-like symptoms, dark urine.

28. Common Diseases of Digestive System (contd.)
 IBS: A common disorder that affects the large intestine. Symptoms
include abdominal cramp, pain, bloating, gas, and diarrhea or
constipation, or both.
It is also known as spastic colon, irritable colon, mucous colitis, and
spastic colitis.
Types: IBS-D (diarrhea), IBS-C (constipation), IBS-M (mixed type)
 IBD: Characterized by chronic inflammation of GI tract. Symptoms
are persistent diarrhea, Abdominal pain, Rectal bleeding/bloody
stools, Weight loss, Fatigue etc.
Types of IBD include: Ulcerative colitis- Occurs in the large intestine
(colon) and the rectum and Crohn’s disease- Occurs any part of the
GI tract from the mouth to the anus.

29. Common Diseases of Digestive System (contd.)
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 Pancreatitis: Inflammation of pancreas. Common symptoms are:
Intense upper abdominal pain, Fever, Rapid pulse, Nausea, Vomiting
etc. Causes are Alcohol, Certain medications, Infections, High
triglyceride levels etc.
 Diarrhea: Loose, watery and possibly more-frequent bowel
movements. Causes: Virus, Bacteria, Parasites, Certain Medications,
GI disorders etc., Common bacteria that cause diarrhea: Escherichia
coli (E. coli), Salmonella, and Shigella.
 Constipation: Infrequent bowel movements or difficult passage of
stools having fewer than three bowel movements a week. Chronic
constipation persists for several weeks.