Lecture notes for medical students

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2. Introduction

3. Introduction
• It is a muscular, highly vascular bag-shaped
organ that is distensible and may take
varying shapes, depending on the build and
posture of the person and the state of
fullness of the organ

4. Parts

5. Parts
• The esophagogastric junction (cardia),
• The cardiac notch (incisura cardiaca gastri)
• Fundus
• Body (corpus)
• Pyloric antrum
• Pyloric canal,
• Greater curvature
• Lesser curvature
• The junction of the vertical and horizontal
parts of the lesser curvature is called

6. Arterial Supply

7. Arterial Supply
Celiac trunk (axis)- 1.common hepatic artery,
2.splenic artery,3 left gastric artery
• 1.Left gastric artery
• 2.Right gastric artery branch from common
hepatic artery
Pancreaticoduodenal artery- branch from common hepatic artery
• 3.Right gastro-omental (gastroepiploic) artery
Splenic artery
• 4.Left gastro-epiploic (gastro-omental) artery
• 5.Short gastric (Vasa Brevia) arteries from splenic
art.

9. Venous Drainage

10. Venous Drainage
• Portal Vein
• left gastric (coronary) vein
• right gastric
• right gastro-omental veins
• left gastro-omental vein
• short gastric veins splenic vein,

11. Lymphatic Drainage
4 levels-
• Level I (perigastric lymph nodes) - Right
paracardiac (1), left paracardiac (2), along
lesser curvature (3) along greater curvature
(4), suprapyloric (5), infrapyloric (6)
• Level 2 - Along LGA (7), along CHA (8),
along celiac axis (9), at splenic hilum (10),
along splenic artery (11)

12. Lymphatic Drainage
4 levels-
• Level 3 - In hepato-duodenal ligament (12),
behind duodenum and pancreas head (13),
at the root of small bowel mesentery (14)
• Level 4 - Mesocolic (15), paraaortic (16)

13. Nerve Supply

14. Nerve Supply
• Parasympathetic-
– Right and left Vagus (N. Of Latarjet)
– Crow’s foot.
• Sympathetic- celiac ganglia (T5-T9).
• plexus Auerbach plexus of Meissner

15. Relations

16. Relations
• Anterior
– left lobe (segments II, III and IV) of the liver
– anterior abdominal wall
– the distal transverse colon.
• Posterior(stomach bed).
– left hemidiaphragm
– Spleen
– left kidney (and adrenal)
– pancreas
– The omental bursa (lesser sac) lies behind the
stomach and in front of the pancreas;

17. Attachments/Supports

18. Attachments/Supports
• To liver by the hepatogastric ligament (the left
portion of the lesser omentum)
• to the left hemidiaphragm by the gastrophrenic
ligament,
• to the spleen by the gastrosplenic/gastrolienal
ligament
• to the transverse colon by the gastrocolic
ligament (part of the greater omentum
• Few peritoneal bands may be present between the
posterior surface of the stomach and the anterior
surface of the pancreas.

19. Physiology

20. Physiology
• Physiology is study of functions.

21. Stomach :Main Functions

22. Stomach :Main Functions
• Storage
• Preparing the chyme for digestion in the
small intestine
• Releasing small quantities of chyme into
duodenum.
• Absorption of water and lipid-soluble
substances (alcohol and drugs)

23. Physiology

24. Physiology
• How it is done ?
• Motility
• Secretion of gastric juice

25. Motility

26. Motility
• Functions
• 1. allows the stomach to serve as reservoir
• 2. breaks food to small particles and mix it
with gastric juice
• 3. empties gastric contents at a controlled
rate

27. Motility
• Reservoir part fundus -1/3 corpus (tonic
contraction)
• Antral pump 2/3 corpus + antrum & pylorus
(phasic contraction)

28. Motility
• Run by intrinsic nervous system.
• The migrating motor complex (MMC)
Empty stomach –Cycles of 90 min.
• Phase I - 40 min quiescent
• Phase II 40 min. three per minute waves
• Phase III 10min High amplitude
contractions.
On eating-
• Relaxation of fundus.
• Strong waves in pyloric antrum against
closed pylorus – milling.

29. Motility: Reservoir
• Receptive relaxation - triggered by
swallowing reflex
• Adaptive relaxation - triggered by stretch
receptors
• Feedback relaxation - triggered by chyme in
small intestine

30. Regulation of gastric emptying

31. Regulation of gastric emptying
• Acidity >Secretin >antral contraction
• Fat > CCK, GIP > reduced gastric emptying
Hyperosmotic solutions >reduced gastric
emptying
• Amino acids>Gastrin> contraction of
sphincter

32. Gastric juice

33. Gastric juice
• HCL
• Pepsinogen
• Electrolytes
• Intrinsic factor
• Mucus (mucus gel layer)

34. Gastric juice :Control of
Secretion
• 1.Endocrine.
• 2. Paracrine. Messengers are produced
locally and have local effects on tissues.
Neurones and endocrine cells both act in
this way.
• 3. Neurocrine (classic neurotransmitter).
Messengers are produced by the neurone
via the synaptic knob and pass across the
synaptic cleft to the target.

35. Gastric juice :Control of
Secretion
• Neural & Hormonal
• Vagus nerve.
• Gastrin
• Enterochromaffin-like cells>Histamine ---
H2 receptor on parietal cells > Proton Pump
(hydrogen–potassium-ATPase) >acid
secretion

36. Phases of Acid Secretion
• Cephalic phase(30%):Smelling, Chewing
and swallowing
• Gastric phase (60%): gastric distention
proteins
• Intestinal phase (10%): digested proteins

37. Inhibition of Acid Secretion
• Inhibitory hormones
• Somatostatin (D-cells) in antrum
• Secretin (S-cells) in duodenum
• Glucose-dependent insulinotropic peptide
(GIP) in duodenum

38. Mucosal defence

39. Mucosal defence
• The gastric mucus layer is essential to the
integrity of the gastric mucosa.
• Produced by the mucus-producing cells of
the stomach and the pyloric glands.
• Protects the gastric mucosa from
mechanical damage and also from the
effects of acid and pepsin.
• Damaged by bile, non-steroidal anti-
inflammatory drugs (NSAIDs), alcohol,
trauma and shock

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