The cardia is the first part of the stomach below the esophagus. It contains the cardiac sphincter, which is a thin ring of muscle that helps to prevent stomach contents from going back up into the esophagus. • The fundus is the rounded area that lies to the left of the cardia and below the diaphragm. • The body is the largest and main part of the stomach. This is where food is mixed and starts to break down

1. Physiology of stomach
By
Dr Iqra Bano Chandio

3. Stomach
• The stomach is a muscular, J-shaped organ in the upper part of the
abdomen.
• It is part of the digestive system, which extends from the mouth to
the anus.
• The size of the stomach varies from person to person, and from meal
to meal.

5. Functions
• The stomach has 3 main functions:
• temporary storage for food, which passes from the esophagus to the
stomach where it is held for 2 hours or longer
• mixing and breakdown of food by contraction and relaxation of the
muscle layers in the stomach
• digestion of food

6. Regions of the stomach
• The stomach is divided into 5 regions:
• The cardia is the first part of the stomach below the esophagus. It
contains the cardiac sphincter, which is a thin ring of muscle that
helps to prevent stomach contents from going back up into the
esophagus.
• The fundus is the rounded area that lies to the left of the cardia and
below the diaphragm.
• The body is the largest and main part of the stomach. This is where
food is mixed and starts to break down.

7. Regions of the stomach
• The antrum is the lower part of the stomach. The antrum holds the
broken-down food until it is ready to be released into the small
intestine. It is sometimes called the pyloric antrum.
• The pylorus is the part of the stomach that connects to the small
intestine. This region includes the pyloric sphincter, which is a thick
ring of muscle that acts as a valve to control the emptying of
stomach contents (chyme) into the duodenum (first part of the small
intestine). The pyloric sphincter also prevents the contents of the
duodenum from going back into the stomach.

13. Protein digestion in stomach

14. Protein digestion in stomach

15. Protein digestion in stomach

17. Gastrin hormone
• when food moves from mouth to the oesophagous and
down into the stomach gastrin is released from G cells of
stomach.
• The secretion of gastrin is stimulated by food arriving in
the stomach in response to eating food (especially
protein), gastrin causes the stomach to produce more
acid and stimulates contraction of muscles in the wall of
part of the stomach; ileum and colon. The contraction
propels food through the digestive tract.
• Secretion of gastrin is inhibited by low pH.

18. CCK (Cholecystokinin)
• Pancreas also secretes digestive enzymes which are guarded by GI
hormone called CCK.
• CCK is released by the cells of duodenum.
• It also tell gall bladder to release a substance called bile, which is
essential for digestion and absorption of fat.
• CCK release is stimulated by fats, proteins and amino acid.

19. Secretin:
• Secretin is a GI hormone that stimulates the secretion of water and
bicarbonate from the pancreas and bile ducts whenever the stomach
empties too much acid into the small intestine. Bicarbonate
neutralizes the acid from the stomach.
• Also increases the release of enzymes from the pancreas.
• Secretin stimulates the secretion of bile in the liver.
• Secretin is secreted in response to the fat in chyme.

20. Gastric Inhibitory Peptide (GIP):
• GIP is also known as Glucose dependent insulinotropic polypeptide.
• GIP is the hormone that is present in the duodenum.
• It decreases the stomach churning in order to slow the emptying of
the stomach.
• It also induces insulin secretion.

21. Somatostatin:
· Somatostatin was initially isolated from the hypothalamus as 1640Da
peptides of 14 amino acids that are inhibited by the release of growth
hormone.
• It is widely distributed throughout the central and peripheral nervous
system.
• It is found in variety of endocrine tissues.