2. Introduction
• GI System is the route through which the food enters the body.
• Normal young healthy adult consumes 1 kg of solid diet and
1-2 L of liquid diet every day.
• The food consumed cannot be utilized by the body directly.
• The process of conversion of complex food substances into
simple food substances that can be absorbed by the body is
known as Digestion.
4. • Made up of:
- GI Tract and the accessory organs
• GI Tract:
Mouth-Pharynx-Esophagus-Stomach-Small Intestine-Large
Intestine
• Accessory Organs:
Teeth,Tongue,Salivary Glands,Exocrine part of the
Pancreas,Liver,Gall Bladder.
5. Wall Of GI Tract
Made of 4 layers:
Mucous Layer
Submucous Layer
Muscular layer
Serous or Fibrous layer
6. Nerve Supply to the GI Tract
• Two types of nerve Supply
- Intrinsic Nerve supply
- Extrinsic nerve supply
1). Intrinsic nerve supply:
- Present within the wall of GI Tract
- Fibers are interconnected and form a network called nerve
plexus. Two types :Auerbach’s Plexus and Meissner’s Plexus
2) Extrinsic Nerve Supply. :
- It is from the Autonomic Nerve System
- Both sympathetic and the parasympathetic division of the ANS
8. Introduction
• Stomach is a hollow organ situated just below the diaphragm
on the left side of the abdominal cavity.
9. • Specialized for accumulation of food
▫ Capable of considerable expansion (can hold 2-3L)
• Gastric juice converts food into semi solid material called
chyme
• 4 Parts of stomach:
▫ Cardia
▫ Fundus
▫ Body
▫ Pylorus
10. Stomach
• Gastric glands are the glands of the stomach.
• Gastric mucosa has numerous openings called gastric pits
• Gastric glands empty into bottom of pits
• The gastric glands are of three types:
-Fundic gland
-pyloric gland
-cardiac gland.
11. • Different cells of Fundic glands are:
▫ Mucous cells
▫ Chief cells
▫ Parietal cells
▫ Enteroendocrine cells
12. Functions of stomach
1).Mechanical Function:
-Storage Function: Food is stores in stomach for 3-4 hrs
-Formation of chyme: Peristalic movement of stomach mixes the
bolus with the gastric juice and forms a semislid material called
chyme.
2).Digestive Function:
-Gastric juice mainly acts on proteins.
-Proteolytic enzymes –pepsin and renin
13. • Pepsin:
-Major proteolytic enzyme .
-secreted as pepsinogen which is inactive
-Products: Proteoses,Peptones,Polypeptides.
• Gastric Lipase:
- Weak lipatic enzyme
- Hydrolyses fats into fatty acids and glycerols
• Others are:
-urase(acts on urea,produces ammonia)
-Rennin(curdles milk)
- Gelatinase-(converts gelatin to peptides)
-Gastric Amylase(Digestion of carbohydrates)
14.
15. Functions
3).Hemopoietic Function:
4)Protective Function:
- Intrinsic factor of castle
-Thick mucus is responsible for
present in gastric juice helps in
erythropoeisis.
- Necessary for the absorption of
Vitamin B12.
- Deficiency leads to pernecious
anaemia
protection of the gastric wall
from injury,irritation.
-prevents the digestive action of
pepsin on the stomach wall.
-Alkaline in nature due to which
it protects the gastric mucosa
from Hcl of the gastric juice
16. Functions
5).Excretory Function:
6).Secretory Function:
- Substances like Toxins, alkaloids
and metals are excreted through
gastric juice
Hcl present in the gastric juice :
- Activated the pepsinogen to
pepsin
- Bacteriolytic action
- Provides the acid medium for
the actions of hormones.
18. Introduction
• Pancreas is a glandular organ in digestive system
• Pancreas is an organ having Dual functions:
- Endocrine function (Islets of Langerhans)-production of Hormones,
secretion of insulin and glucagon onto the blood.
- Exocrine function(Acinar cells)-secretion of digestive juice called as
pancreatic juice
- Most cells make up pancreatic acini, which produce pancreatic
juice
19. • Secretes pancreatic juice into a pancreatic duct; pancreatic
duct leads to duodenum (small intestine).
20. Functions of pancreas
1). Digestive Functions of pancreatic juice:
a. Digestion of Proteins :
- Proteolytic enzymes: trypsin, chymotrypsin, carboxypeptidase ,
nucleases , elastase , collagenase
proteins
peptides;
• stored and released as inactive form in zymogen granules
• trypsinogen is activated to trypsin by enterokinase
• trypsin then activates chymotrypsin and carboxypeptidase
21. b. Digestion of Carbohydrates:
• (Starch and Glycogen)
maltose and dextrin
With the help of pancreatic amylase .
c. Digestion of Fats/Triglycerides :
• Fats/Triglycerides
2 fatty acids + monoglyceride
With the help of pancreatic lipase,colipase,cholestrol ester
hydrolase, phospholipase A and B,Bile salt-lipase.
d. Digestion of Nucleic Acids:
• Nucleic acids
nucleotides.
With the help of nucleases
22. 3).Endocrine Function:
Consists of Islets of langerhans.(alpha cells,Beta cells and delta
cells).
2). Neutralizing action of pancreatic Juice:
- Bicarbonate ions are also released to neutralize acidic chyme
entering from the stomach.
- This protects the intestine from destructive action of the acidic
chyme.
24. Introduction
•
•
•
•
Largest internal organ.
Location: below diaphragm / right side
Contains hepatocytes
also contains Kupffer’s cells (macrophages)
remove and destroy:
-microbes;
-foreign matter.
-worn platelets and erythrocytes
25.
26. Functions Of Liver
Metabolism of monosaccharides, lipoproteins, amino
acids.
Storage (glycogen, Vitamin A, B12, D, iron),
Filtering of blood (worn blood cells and debris),
Destruction of toxic chemicals (alcohol and drugs),
Production/secretion of bile.
Heat Production
Hemopoetic Function
Inactivation of Hormones and drugs(catabolism)
Hemolytic Function (kupffer’s cells)
Synthesis of glucose, few proteins
30. • 3 Parts:
-Duodenum-nearest stomach
-Jejunum- mid-region
-Ileum- near large intestine
• Mucous membrane of SI is covered by minute projections
called as villi
• Primary site for digestion and absorption of nutrients
• Bile duct and pancreatic duct empty into duodenum
31. Functions of Small Intestine
Digestive Functions:
• Secretions from SI is called succus entericus.
• Enzymes of succes entericus acts on partially digested food
and converts into final digestive products.
32. Functions
Digestive Function:With the help of proteolytic and
Amyloytic ,lipolytic enzyme.
Protective Function: Mucus secreted by succus entericus
protects the wall of intestine and paneth cells(secretes
defensins)
Activator Function: Enterokinase activated trysinogen to
trypsin.
Hemopoetic Function(intrinsic factor of castle)
Hydrolytic Function(helps in enzymatic reactions)
Secretory function(secretes enterokinase,succus entericus)
Mechanical Function
Absorptive Function
Hormonal Function (secretes GI hormones like secretin)
34. • Parts of Large Intestine:
o
cecum - nearest ileum of small intestine; (appendix is a
blind pouch in this region);
o
colon –
majority of length;(ascending,transverse,Descending,sigmoid)
o
rectum - distal region of colon;
o
anal canal - narrowing of rectum & opening to outside;
•
•
•
•
Reabsorbs water and electrolytes
Eliminates waste
NO Villi
Mucosa contains numerous tubular glands called crypts
▫ Responsible for mucus secretion
35. Functions of Large Intestine
Secretion - only mucin and other inorganic substances(cl)
Absorption of water , electrolytes.
Formation of Feces –unwanted substances form feces
Bacterial flora of LI - synthesises vit B12,folic acid,vit K.
Excretory Function-Excretes heavy metals like
bismuth,mercury,lead through faeces.
37. Endoscope
• Endoscopy is a nonsurgical procedure used to examine a
person's digestive tract.
• Using an endoscope, a flexible tube with a light and camera
attached to it, your doctor can view pictures of your digestive
tract on a color TV monitor.
38.
39. • An endoscopy is often used to confirm a diagnosis when other
devices, such as an MRI , X-ray, or CT scan are considered
inappropriate.
•
•
•
•
•
- The following conditions and illnesses are most commonly
investigated or diagnosed with an endoscopy:
Breathing disorders
Chronic diarrhea
Incontinence
Internal bleeding
Irritable bowel syndrome
