3. Stomach is a j shaped
enlargement of GI tract directly
inferior to the diaphragm in the
abdomen. The stomach
connects the esophagus to the
duodenum, the first part of
small intestine. It is where
digestion of protein begins. The
stomach has three tasks. It
stores swallowed food. It mixes
5. DEVELOPMENT DURING
THE FETAL PERIOD
The stomach begins to form as
fusiform(spindle-shaped) dilation in the
foregut during the 4th week.
The developing stomach is attached to the
body walls by dorsal and ventral
mesenteries.
The dorsal wall of stomach grow faster
than the ventral wall.
The differentiation start from the greater
and lesser curvatures of stomach.
6. During 7th week , the stomach rotates 90
degrees cloackwise about a longitudinal
axis this produce a space behind called
lesser sac (omental bursa).
During the 8th week the stomach and
duodenum rotate about ventrodorsal (A-P)
axis , pulling the end of stomach upward
and attain a C-shaped. Postnatal position
of stomach and deudenum is attained
9. ANATOMY
In adult life, stomach located T10 and
L3 vertebral segment
Can be divided into anatomic regions
based on external landmarks
–4 regions
i. Cardia
ii. Fundus
iii. Corpus (body)
iv. Pyloric part
10. 4 PARTS
Cardia- region just distal to
the GE junction
Fundus- portion above and
to the left of the GE junction
Corpus- region between
fundus and antrum
Margin not distinctly
external, has arbitrary borders
Pyloric part- which is
divided into the pyloric
antrum and pyloric canal
and is the distal end of the
11. Stomach is positioned between the
abdominal esophagus and the small
intestine, it is in the epigastric, umbilical, and
left hypochondrium regions of the abdomen.
12. OTHER FEATURES
Openings:
- Gastroestophageal: to esophagus
-Pyloric: to duodenum
Sphincters:
-The cardiac sphincter(lower
esophagus sphincter) closes off the top end
of the stomach.
- The pyloric sphincter closes of
the bottom.
13. Anterio- superior: in contact with Left hemi-
diaphragm, left lobe and anterior segment of right lobe
of the liver and the anterior parietal surface of the
abdominal wall
Posterio-inferior: Left diaphragm, Left kidney, Left
adrenal gland, and neck, tail and body of pancreas
The greater curvature is near the transverse colon
and transverse colon mesentery
The concavity of the spleen contacts the left lateral
Surface:
• Anterio-superior surface
• Posterio-inferior surface
14. Curvature:
The greater curvature,
which is a point of
attachment for the
gastrosplenic ligament
and the greater
omentum
The lesser curvature,
which is a point of
15. Layers of peritoneum attached to the stomach:
Lesser omentum: attaches the liver to the lesser curvature.
Greater omentum: attaches the greater curvature to the
posterior body wall
16. VASCULATURE
Arterial blood supply:
– 3 Branches
• Left Gastric Artery
– Supplies the cardia of the stomach and distal esophagus
• Splenic Artery
– Gives rise to 2 branches which help supply the greater
curvature of the stomach
» Left Gastroepiploic
» Short Gastric Arteries
• Common Hepatic or Proper Hepatic Artery
– 2 major branches
» Right Gastric- supples a portion of the lesser
curvature
» Gastroduodenal artery
-Gives rise to Right Gastroepiploic artery
-helps supply greater curvature in
conjunction with Left Gastroepiploic Artery
17. Venous Drainage
Parallels arterial supply
Rt &Lt gastric veins drain to the
portal
Rt gastroepiploic drains to the
SMV
Lt gastroepiploic drains to the
splenic
18.
19.
20. Lymphatic Drainage:
• Lymph from the proximal
portion of the stomach drains
along the lesser curvature
first drains into superior
gastric lymph nodes
surrounding the Left Gastric
Artery.
• Distal portion of lesser
curvature drains through the
suprapyloric nodes.
• Proximal portion of the
greater curvature is supplied
by the lymphatic vessels that
21. INNERVATION
The main innervations are Left
and Right Vagus Nerves.
Parasympathetic
innervation of
Stomach- Vagus Nerve
90% of fiber in vagal
trunk is afferent (info
transmitting from
stomach to CNS)
Sympathetic
innervation of
Stomach- Splanchnic
24. CELLS
o Parietal cells
Location- neck of gastric pit
Stimulated by Ach, Histamine and Gastrin
Secretes HCl + Intrinsic Factor
o Chief Cells
Location- base of gastric pit
Stimulus- Vagal
Secretes Pepsinogen (eventually leads to pepsin- digestive enzyme)
Antral Glands
o Gastrin cells
Location- mucosa of distal stomach
Stimulus- amino acids
Secretion- Gastrin (stimulates HCl production by way of pariet
cells)
o Somatostatin
Location- mucosa of distal stomach + Duodenum
Stimulus- HCl or low pH in duodenum
28. Gastric Motor Activity
Main function of gastric motility
-Accommodate and store ingested meal
-Grind down solid particles(tituration)
-Empty all constituents of the meal in a
carefully controlled and regulated fashion
into the
duodenum.
29. Gastric Anatomy
3 Distinct regions
1. Proximal- cardiac, fundus, proximal
body
2. Distal- distal body and antrum
3. Pylorus
30. Electrophysiology
Slow wave – omnipresent, highly
regular and recurring electrical pattern
in GI tract
Does not lead to contractions, but
maximal frequency of contractile
activity is directly related to slow wave
frequency
Contractions are related to spike
potentials
31. Slow waves thought to originate in
“gastric pacemaker” site along the
greater curvature in the proximal to
middle body
Migrate in both circumferential and
longitudinal directions
Electrical signals do not traverse the
pylorus
34. Fundic smooth muscle cells are electrically
silent – resting membrane potential is already
above the mechanical threshold
Generates tone – AP not generated – neural
and hormonal input modulates tone
rather than generating peristaltic contractions
35. GI Motor Activity
• Motor activity is highly organized into a
distinct and cyclically recurring sequence
of events known as MMC (migrating motor
complex)
• 3 distinct phases of motor activity
– I – quiescence
– II – random and irregular contractions
– III – burst of uninterrupted phasic contractions
• Patterns of MMC activity commence and
end simultaneously at all sites
36. Fasted Stomach
• Phase III
– Basal tone in LES in increased and exhibits
superimposed phasic contractions
– Tone increases in proximal stomach
– One cycle/min high-amplitude waves develop in body
– Distal antrum 3-5 cycles/min
– Antropyloroduodenal coordination increases and
high-amplitude contractions propagate through the
antrum across the pylorus
• Extrinsic nerves (vagus) and hormonal factors
(motilin) are involved
– Phase III – may be induced by motilin released from
37. Fed Stomach
• Initiation of swallow – fundus undergoes vagally
mediated receptive relaxation
• As meal enters stomach tone and phasic
contractions in proximal stomach are inhibited
– Accommodation – 2-3 fold increase in gastric volume
• Fundic tone – balance between cholingeric
• ( excitatory) and nitrergic (inhibitory) input
• Fasting – cholinergic dominates
• Meal – accommodation response triggered by
distention-induced stimulation of
mechanoreceptors
38. • NO is primary inhibitor of fundic tone
• Other factors modulate fundic tone
-Relaxation
• Antral distention (gastrogastric reflex)
• Duodenal acidification
• Lipid and protein (duodenogastric reflex)
• Colonic distention (cologastric reflex)
• Food ingested results in abolition of cyclical pattern of MMC
• Replaced by random contractions called fed pattern
• May last 2.5-8 hours
39. Gastric Emptying
• Gastric emptying dependent on the
propulsive force generated by tonic
contractions of proximal stomach and
• resistance presented by antrum, pylorus,
duodenum
• Fundamental property of stomach – ability
to differentiate among different types of
• meals and the components of individual
meals
infuse fluid fluid out
time
volume of stomach
tension in
stomach wall
40. i. liquids
• Liquids rapidly disperse and begin to empty
without lag period
• Non-nutrient liquids empty rapidly
• Nutrient containing liquids are retained longer
and empty more slowly
• Liquids
• Emptying of liquids follows a simple, exponential
pattern
• Rate influenced by volume, nutrient content and
osmolarity
• Rate of emptying determined by gastric volume
41. ii. solids
• 2 phases – initial lag phase followed by a linear emptying
phase
• Solid component is first retained in proximal stomach
• As liquid empties, solid moves to antrum and is emptied
• Essential component of normal response is ability of
antropyloric region to discriminate solid particles by size
and restrict emptying of particles >1mm in diameter
• Antropyloric mill grinds down (titurates) larger particles
to smaller ones
• During tituration, solid emptying does not occur
• Duration of lag phase is directly related to size and
consistency of solid component of the meal
– Typical solid-liquid meal - ~60min
42. • Tituration – coordinated high-amplitude
waves originate in proximal antrum and are
propagated to pylorus
• Pylorus opens and duodenal contractions
are inhibited permitting trans-pyloric flow of
liquids and suspended or liquefied solid
particles
• When liquids and solids reach distal antrum,
pylorus closes promoting retropulsion of
particles too large to have been exited
• Pylorus regulates passage of material
• Relatively narrow and fixed lumen
• Maintenance of pyloric tone
43. iii. Fatty food & indigestible
food
• Liquid at body temperature
• Float on top of liquid layer but empty more
slowly
• Products of fat digestion in duodenum are
potent inhibitors of gastric motor events
and gastric emptying
Indigestible Solids
• Not emptied in immediate post-prandial
period
44. GASTRIC ACID SECRETION
Acid production by the parietal cells in the stomach depends on
the generation of carbonic acid
subsequent movement of hydrogen ions into the gastric lumen
results from primary active transport.
45.
46. The acidity in
the gastric
lumen converts
the protease
precursor
pepsinogen to
pepsin;
subsequent
conversions
occur quickly
52. COMMON DISEAESES
• Peptic ulcer
A lesion in the lining of the digestive tract,
typically in the stomach or duodenum, caused
by the digestive action of pepsin and stomach
acid
• Gastritis
Inflammation of the lining of the stomach
• Gastroparesis
Condition consisting of a paresis of the
53. Stomach cancer
Gastric cancer can develop in any part of the
stomach and may spread throughout the
stomach and to other organs; particularly the
esophagus, lungs, lymph nodes, and the
liver. stomach cancer causes about 800,000
deaths worldwide per year.
Peptic ulcer disease
An ulcer of an area of the gastrointestinal
tract that is usua
