Download Middle Digestive Tract

Stomach and small intestine
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Stomach – embryogenesis and histogenesis
Small intestine – embryogenesis and histogenesis
Structural organization of the stomach and small
intestine – macroscopic and microscopic anatomy
Roentgen anatomy of the stomach and small
intestine
Blood supply and innervation of the stomach
and small intestine
SPLANCHNOLOGY
Stomach – gaster, ventriculus
The most dilated (J-shaped) part
of the digestive tube – 1-1.7 l
situated in the upper abdominal
cavity, just below the diaphragm
storage and break food down, and
mixing it with juices secreted by
its lining – chemical digestion
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Embryonic development
Embryogenesis:
develops from the foregut
starting at the 4th week
fusiform dilation of the foregut
rotates 90° clockwise around
its longitudinal axis
Histogenesis:
from the endoderm
of the foregut:
gastric epithelium
o stratified columnar epithelium
simple columnar (2nd mo.)
gastric glands
gastric pits – middle of 2nd mo.
from the surrounding mesenchyme:
connective tissue components
o serosa – 2nd mo.
(splanchnopleural mesoderm)
smooth muscles – 2nd – 4th mo.
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Macroscopic anatomy
Four distinct anatomical regions:
the cardia, pars cardiaca –
gastric orifice, ostium cardiacum
the fundus, fundus gastricus
the body, corpus gastricum
the pylorus, pars pylorica:
pyloric antrum
pyloric canal
pyloric sphincter
greater curvature, curvatura gastrica major
lesser curvature, curvatura gastrica minor
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Topography of the stomach
The skeletotopy:
in upper part of the abdominal cavity,
under the left diaphragmatic vault
in the left hypochondriac region
partly in the epigastric region
the cardia – to the left of
Th10-Th11 vertebrae
the pylorus – to the right of
Th12-L1 vertebrae
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Topography of the stomach
The somatotopy –
intraperitoneal position:
stomach bed (gastric chamber)
anterior gastric surface – 40 cm2
(beneath the Traube’s space)
operative approach to the stomach
contact surfaces
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Wall of stomach
Three major layers:
the mucosa, tunica mucosa
submucosa, tela submucosa
muscularis, tunica muscularis
the serosa, tunica serosa
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Wall of stomach
Three major layers:
the mucosa, tunica mucosa
submucosa, tela submucosa
muscularis, tunica muscularis
the serosa, tunica serosa
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Histological structure
Three distinct histological parts:
cardiac region
the cardia, pars cardiaca
fundic region
the fundus and
the body, corpus gastricum
pyloric region
the pylorus, pars pylorica
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Gastric mucosa
mamillated areas,
areae gastricae:
villous folds, plicae villosae
gastric pits
(foveolae gastricae)
gastric folds (rugae),
plicae gastricae:
along the curvatures –
longitudinal mucosal folds
within lesser curvature –
stomach road, “Magenstrasse”
for gastric emptying
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Gastric mucosa
mamillated areas,
areae gastricae:
villous folds, plicae villosae
gastric pits
(foveolae gastricae)
gastric folds (rugae),
plicae gastricae:
along the curvatures –
longitudinal mucosal folds
within lesser curvature –
stomach road, “Magenstrasse”
for gastric emptying
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Gastric mucosa
lamina epithelialis – single-layered columnar epithelium:
surface mucous cells (cell renewal 4-7 days) and pit cells
lamina propria mucosae – gastric glands
lamina muscularis mucosae – causes changes in the
mucosal surface relief
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Gastric glands
proper gastric (fundic) glands ~35 million
glandulae gastricae propriae
pepsinogen and hydrochloric acid
gastric intrinsic factor
cardiac glands – glandulae cardiacae
pyloric glands – glandulae pyloricae,
~3.5 million (total secretory surface of 0.4 m2)
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Gastric glands
proper gastric (fundic) glands – parts:
isthmus, neck and base (pars principalis)
cell types:
undifferentiated (stem) cells – in the upper neck region
epitheliocyti nondifferentiati glandulae pyloricae
chief cells, exocrinocyti principales: pepsinogen and lypase
parietal cells, exocrinocyti parietales: HCl, intrinsic factor
mucous neck cells, mucocyti cervicales
enteroendocrine cells, endocrinocyti: gastrin,
SOM, VIP, SER, histamine, ghrelin, bombesin
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Histological structure
Gastric submucosa, tela submucosa:
dense connective tissue with blood and lymph vessels
Gastric muscularis, tunica muscularis:
inner oblique layer, fibrae obliquae
middle circular layer (m. sphincter pyloricus) – poorly developed
in the periesophageal region
outer longitudinal layer (stratum longitudinale) – absent from
much of the anterior and
posterior stomach surfaces
Gastric serosa, tunica serosa:
part of peritoneum
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Roentgen anatomy
Saccus digestorius:
fornix gastricus
corpus gastricum
sinus ventriculi
Canalis egestorius:
pars pylorica
pylorus
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Functional types of stomach
Four major stomach types:
hypertonic (or short) stomach
orthotonic stomach
hypotonic (or long) stomach
atonic stomach
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Vessels of the stomach
Blood supply:
by arteries from
the celiac trunk
Venous drainage:
into the hepatic portal vein
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Lymphatic drainage
from the medial ⅔ of
the gastruc fundus and body to:
lymph nodes along the
lesser gastric curvature
pericardial lymph nodes
posterior mediastinal lymph nodes
from the rest of
the fundus and body to:
pancreatic and splenic nodes
from the lower gastric part to:
lymph nodes along the
right gastro-omental artery
lymph nodes in the pyloric region
hepatic lymph nodes
superior mesenteric lymph nodes
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Innervation of the stomach
gastric plexus,
anterior and posterior:
sympathetic
– sympathetic trunk:
splanchnic nerves
coeliac ganglion
parasympathetic – vagus nerve:
gastric branches of anterior and
posterior vagal trunk
subserosal plexus,
myenteric (Auerbach’s) plexus and
submucosal (Meissner’s) plexus
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Small intestine, intestinum tenue
Small intestine – convoluted tube:
initial part of the intestinal tract
extends from the pylorus
to the ileocaecal valve
the longest component of the
digestive tract – 6-8 m length
diameter – 4-3 cm
capacity – 4 l
the principal site for the digestion
of food and for absorption of its
products – functional peculiarities
Three anatomic segments:
duodenum – 25-30 cm long
jejunum – 2.5 m long
(first 2/5 of the total length of small bowel)
ileum – 3.5 m long (3/5 of the total length)
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
The duodenum, duodenum
Localization and skeletotopy:
adherent to the posterior abdominal wall
entirely above the level of the umbilicus
projected into the:
epigastric region
umbilical region
horseshoe-shaped;
enclosing the head of the pancreas
immobile, has no mesentery
Four anatomical parts:
superior part, pars superior
– 5 cm
descending part, pars descendens – 7.5 cm
horizontal part, pars horizontalis – 10 cm
ascending part, pars ascendens
– 2.5 cm
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Duodenum in situ
Duodenal position and relations:
superior part
– intraperitoneal position
descending part
horizontal part
ascending part
–
retroperitoneal
position
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Duodenal wall
Three major layers:
mucosa, tunica mucosa –
impressively articulated relief
plicae circulares (Kerkring’s folds)
submucous layer, tela submucosa
muscular layer, tunica muscularis
serosa, tunica serosa
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Duodenal mucosa
Tunica mucosa:
villi
intestinal
glands
duodenal
glands
lamina epithelialis – simple columnar epithelium
lamina propria – lymphocytes and lymphatic nodules (GALT)
lamina muscularis mucosae – smooth muscle fibers
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Intestinal villi, villi intestinales
duodenal villi – a total of 4 million villi
22-40/mm2 – duodenum and jejunum, 18-31 /mm2 – ileum
broad, leaf-like – in duodenum
long, slender but short – in mesenteric small intestine
epithelium – simple columnar absorptive (cell renewal 3-6 days)
stroma villi – loose connective tissue (lamina propria)
lymphatic capillary, vas lymphaticum centrale
blood vessels network of fenestrated capillaries in the periphery
smooth muscle cells – villi contract and shorten intermittently
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Intestinal villi, villi intestinales
Surface epithelium – cell types:
enterocytes, epitheliocyti columnares –
90% of all cells
brush border (absorption)
goblet cells, exocrinocyti caliciformis –
unicellular mucin-secreting glands
enteroendocrine cells – CCK, secretin and GIP
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Intestinal glands,
glandulae intestinales
Crypts of Lieberkühn – 150 million:
simple tubular glands, partially branched
secretion of intestinal juice, succus entericus
located in the lamina propria mucosae
Cell types in the crypt epithelium:
columnar intestinal cells, enterocytes
undifferentiated columnar cells – stem cells (mitoses)
typical goblet cells – acid glycoproteins of the mucin
Paneth cells – lysozyme, glycoproteins, several peptidases
enteroendocrine cells – APUD cells, DNES, GEP system
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Duodenal glands,
glandulae duodenales
Brunner’s glands:
branched compound tubular submucosal glands
mucus-rich alkaline secretion to protect the duodenal
mucous membrane from the acidic gastric juice
cell types – eosinophilic with clear cytoplasm
short columnar cells of mucous type
goblet cells
mucin
parietal cells
Paneth cells
enteroendocrine cells
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Duodenal wall
Muscularis externa, tunica muscularis – well developed:
inner circular layer
myenteric (Auerbach’s) nerve plexus
outer longitudinal layer
Serosa, tunica serosa (adventitia):
simple squamous epithelium
blood and lymphatic vessels, nerve trunks
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Mesenteric small intestine
Mesenteric small intestine:
intraperitoneal position
projected into the:
mesogastric region
hypogastric region
The jejunum, jejunum:
horizontally oriented folds
to the left of median plane
begins at the duodenojejunal flexure (L2)
The ileum, ileum:
vertically oriented folds
to the right of median plane
extends to and ends at the ileocaecal valve (L4)
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Histological structure of mucosa
Mucosa, tunica mucosa:
lamina epithelialis – plicae circulares (Kerkring’s folds/valves)
simple columnar (microvillous) absorptive epithelium
intestinal villi and intestinal glands
lamina propria – loose connective tissue
blood and lymphatic vessels, muscle of Brücke
solitary lymphatic nodules – scattered throughout
aggregated lymphatic nodules (Payer’s patches) – in ileum
lamina muscularis mucosae
circular and longitudinal layers of smooth muscle cells
submucosa, tela submucosa
– well developed
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Histological structure of the wall
Muscularis externa, tunica muscularis – peristalsis
inner circular layer – thick, bundles
ileocaecal sphincter
myenteric (Auerbach’s) nerve plexus
outer longitudinal layer – complete
Subserosa, tela subserosa
Serosa, tunica serosa – mesenterium:
blood and lymphatic vessels
nerves
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Blood supply of small intestine
Duodenum – the celiac trunk and
superior mesenteric artery:
right gastric artery
hepatic artery proper and
gastroduodenal artery
superior pancreaticoduodenal and
inferior pancreaticoduodenal arteries
Mesenteric small intestine –
superior mesenteric artery:
jejunal and ileal branches
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Venous drainage from intestinal wall
Venous drainage from:
the duodenum –
pancreaticoduodenal veins
right
v. portae
left
v. splenica (lienalis)
the mesenteric small intestine –
vv. jejunales et ilei v. portae
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Lymphatic drainage from intestinal wall
Lymphatic drainage from:
the duodenum
pancreaticoduodenal lymph nodes
hepatic lymph nodes
the mesenteric small intestine
celiac lymph nodes
mesenteric lymph nodes
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Innervation of small intestine
coeliac plexus – duodenum
myenteric (Auerbach’s) plexus and
submucosal (Meissner’s) plexus –
mesenteric small intestine
sympathetic – sympathetic trunk:
coeliac ganglion
superior mesenteric ganglion
parasympathetic – vagus nerve
coeliac branches
intestinal branches
Prof. Dr. Nikolai Lazarov
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SPLANCHNOLOGY
Voltaire
(1694-1778)
Thank you ...
“The
fate of a nation has often depended on
the food or bad digestion of a prime minister”
Prof. Dr. Nikolai Lazarov
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