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Abdominal viscera
Introduction
Stomach
Small intestines
Large intestines
Liver
pancreas
Spleen
26/06/2016
BAAB
@2016
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Abdominal viscera are organs of the abdominal
cavity.
They are divided into intraperitoneal which are
covered (surrounded) by the peritoneum and
extraperitoneal organs which are outside the
peritoneum.
Some organs share the two sides, they are both
intra and extra peritoneal.
All extra peritoneal organs are found in the
posterior abdominal wall unlike the anterior
abdominal wall which is formed of the rectus
sheeth.
Location and structure:
 This is a dilated organ of the alimentary canal
situated between the esophagus and the small
intestines.
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It occupies the left upper quadrant, epigastric
and the umbilical region much of it undercover of
the lower ribs.
Its long axis passes downwards anf forward to
right and then backward and slightly backward.
It is roughly J-shaped with two openings cardiac
and pyloric orifices.
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It has two curvetures, greater (extending from
left of the cardiac orifice over the dome of the
fundus through the left border to the pylorus)
and lesser curveture (right border).
It has two surfaces, anterior and posterior
surfaces. The surfaces are covered by the
omentum which forms the lesser omentum or
gastrosplenic ligament to attach to the spleen
and the greater omentum which extend to the
transverse colon.
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The stomach is divided into the following parts:
◦ Fundus: dome – shaped projecting upwardly and to the left of
the cardiac, usually full of gas.
◦ body: extending from the level of the cardiac orifice to the
level of the insura angularis
◦ Pyloric antrum: this extend from the insura angularis to the
pylorus.
◦ Pylorus: a tubular part with thick muscular form called pyloric
sphincter. The cavity of the pylorus is the pyloric canal.
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Stomach – Blood supply
Blood supply:
Arteries.
 Main arterial source is the celiac trunk of abdominal aorta.
 The right gastric artery arise from the hepatic artery of
celiac trunk to supply the lesser curvature of the stomach.
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The left gastric artery arise from the celiac trunk and
supply superior part of the stomach.
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The short gastric artery arises from the splenic artery and
supply the fundus of the stomach.
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The right gastroepiploic (gastro-omental) artery arise
from the gastroduodenal branch of hepatic artery and
supply the lower part of the greater curveture.
The left gastroepiploic (gastro-omental) artery arise from
the spleenic artery and supply the upper part of the
greater curveture
Veins:
 The veins drain into the portal circulation
◦ The left and right gastric veins drain directly into the
portal vein.
◦ The short gastric vein and the left gastroepiploic vein
join the splenic vein.
◦ The right gastroepiploic vein join the superior
mesenteric vein.
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Lymphatic drainage:
◦ The lymph vessels follow the artery into the right and
left gastric nodes, the left and right gastroepiploic
nodes and the short gastric nodes.
◦ All lymph from the stomach passes to the celiac
nodes located around the root of celiac trunk on the
posterior abd. Wall.
Nerve supply:
 The sympathetic fibres from the celiac
plexus and parasympathetic fibres from
the right and left vagus nerves.
◦ The anterior vagal trunk mainly from the left
vagus nerve supply the anterior surface of the
stomach and the pyrolus. It also carries nerve
fibres for pain transmission.
◦ The posterior vagal trunk mainly from the right
vagus nerve supply the posterior surface of the
stomach. It also carries secretomotor nerve
fibres to gastric glands and gastric wall
muscles.
Functions of the stomach:
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1. Digestion-. The stomach releases proteases (proteindigesting enzymes such as pepsin) and hydrochloric acid,
which kills or inhibits bacteria and provides the acidic pH
of two for the proteases to work.
Food is churned by the stomach through peristalsis –the
boluses are converted into chyme (partially digested food).
Chyme which enters the duodenum to begin extraction of
nutrients.
Depending on the quantity and contents of the meal, the
stomach will digest the food into chyme anywhere
between forty minutes and a few hours.
The average human stomach can comfortably hold about
a litre of food.
Gastric juice in the stomach also contains inactive
pepsinogen which is activated by Hydrochloric acid to the
active form pepsin, that breaks down proteins into
polypeptides.
2.Absorption
 Although the absorption is mainly a function
of the small intestine, some small are
absorbed through stomach lining. This
includes:
Water, if the body is dehydrated
Medication, like aspirin
Amino acids
10–20% of ingested ethanol (e.g. from alcoholic
beverages)
◦ Caffeine
◦ Water-soluble vitamins
◦ The parietal cells of the stomach are responsible for
producing intrinsic factor, which is necessary for the
absorption of vitamin B12. B12 is used in cellular
metabolism and is necessary for the production of
red blood cells, and the functioning of the nervous
system.
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3. Control of secretion and motility
 The movement and the flow of chemicals into
the stomach are controlled by both the
autonomic nervous system and by the various
digestive system hormones:
 The hormone gastrin for secretion of HCl from
the parietal cells, and pepsinogen from chief
cells in the stomach.
 Gastrin released by G cells in the stomach also
causes increased motility and distension of the
antrum.
4. Temporaly storage
 The stomach pushes food into the small
intestine only when the intestine is not busy.
While the intestine is full and still digesting
food, the stomach acts as storage for food.
5. Stomach as nutrition sensor
 The stomach can "taste" sodium glutamate
using glutamate receptors and this
information is passed to the lateral
hypothalamus and limbic system in the
brain as a palatability signal through the
vagus nerve.
 The stomach can also sense, independently
to tongue and oral taste receptors, glucose,
carbohydrates, proteins, and fats. This
allows the brain to link nutritional value of
foods to their tastes.
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The small intestine or small bowel is the longest part of the
GIT extending between the pylorus the stomach and the
ileocaecal junction, and is where most of the digestion and
absorption of food takes place.
Structure:
 The small intestine has three distinct regions – the
duodenum, jejunum, and ileum.
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The average length of the small intestine in an adult human
male is 6.9 m (22 ft 8 in), and 7.2 m (23 ft 6 in) in an adult
female. [It can vary greatly, from as short as 4.6 m (15 ft) to
as long as 9.8 m (32 ft).Recent studies indicate that small
intestine may be shorter, around 3.5 m (11 ft 6 in), and that
the length is less affected by age after childhood than
expected]
It is approximately 2.5–3 cm in diameter. The surface area of
the human small intestinal mucosa averages 30 square
meters
Fig:
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The duodenum is a short structure (about 20–
25 cm (8 – 10 in) long continuous with the
stomach
It is shaped like a "C". It surrounds the head of
the pancreas and fixed to the posterior
abdominal wall.
The duodenum contains Brunner's glands,
which produce a mucus-rich alkaline secretion
containing bicarbonate. These secretions, in
combination with bicarbonate from the
pancreas, neutralizes the stomach acids
contained in gastric chyme.
The duodenum consists of four parts
◦ 1st part is 5cm(2in) long, runs upwards and backwards
from the pylorus to the right side of the 1st lumbar
vert.
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Fig: The section of small intestine - Duodenum
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2nd part is 8cm(3in) long, runs vertically downwards
anteriorto the hilum of the right kidney and the
2nd – 3rd lumbar vert. The main pancreatic duct opens
into it this part.
3rd part is 8cm(3in) long, runs holizontally to the left
on the subcostal plane following the lower margin of
the pancreas.
4th part is 5cm(2in) long, runs upwards and to the left
to the duodenojejunal flexure. The flexure is held in
its position by the ligament of treitz which is
attached to the right crus of the diaphragm.
Blood supply:
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The upper half by the superior pancreaticoduodenal
branch from the gastroduodenal artery.
The lower half by inferior pancreaticoduodenal branch of
superior mesenteric artery.
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Veins: superior pancreaticoduodenal to the
portal vein and the inferior
pancreaticoduodenal to the superior
mesenteric vein.
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Lymph drainage: lymph vessel follow the
arteries and drain upwards via
pancreaticoduodenal nodes to gastroduodenal
nodes to the celiac trunk.
Nerve supply: sympathetic and
parasympathetic (vagal) from celiac and
superior mesenteric plexus.
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Jejunum and Ileum:
These measures 6m (20ft), jejunum 2.4m (7.9ft),
ileum 3.6m (12.1ft).
Jejunum is the upper 2/5 of the total freely
mobile length extending from the
duodenojejunal frecture to the ileocecal junction.
The two parts are in living distinguished by
1. The jejunum lie coiled in the upper part of pertoneal
cavity below the left side of the transverse mesocolon
while the ileum occupy the lower part of the cavity and
in the pelvis.
2. The jejunum is wider bored, thicker walled and redder
than the ileum
3. The jejunal mesentery is attached on the posterior
abdominal wall above and to the left of abd. Aorta,
while the ileal attaches below and right side of the
aorta.
4. the jejunal mesenteric vessels form one or
two arcades with long and infrequent
branching passing to the intestinal wall.
Ileum receives numerous short terminal
vessels arising from series of three or four
or more arcades.
5. Jejunal fat deposits at the root of
mesentery and scant near the intestial wall,
ileal fats deposit throughout that it extend
from the root to the intestinal wall.
6. In the living, payer’s patch seen in the
lower part of the wall of the ileum.
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Fig: An arcade of small intestine
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Blood supply: from the superior mesenteric
artery and the ileocecal artery of the lower
part of the ileum.
Veins correspond to the artery and drain into
the superior mesenteric vein.
Lymphatic drainage to the superior
mesenteric nodes situated around the origin
of the superior mesenteric artery.
Nerve supply: sympathetic and
parasympathetic (vagal) from superior
mesenteric plexus
Functions
1. Digestion
 The small intestine is where most chemical
digestion takes place.
◦ Many of the digestive enzymes that act in the small
intestine are secreted by the pancreas and liver and
enter the small intestine via the pancreatic duct.
◦ Pancreatic enzymes and bile from the gallbladder enter
the small intestine in response to the hormone
cholecystokinin, which is produced in the small intestine
in response to the presence of nutrients.
◦ Secretin, another hormone produced in the small
intestine, causes additional effects on the pancreas,
where it promotes the release of bicarbonate into the
duodenum in order to neutralize the potentially harmful
acid coming from the stomach.
◦ The three major classes of nutrients that undergo
digestion are proteins, lipids (fats) and carbohydrates:
2. Absorption
 Digested food is now able to pass into the blood vessels in
the wall of the intestine through either diffusion or active
transport.
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The small intestine is the site where most of the nutrients
from ingested food are absorbed. The functions of the
plicae circulares, the villi, and the microvilli are to increase
the amount of surface area available for the absorption of
nutrients, and to limit the loss of said nutrients to
intestinal fauna.
Each villus has a network of capillaries and fine lymphatic
vessels called lacteals close to its surface. The epithelial
cells of the villi transport nutrients from the lumen of the
intestine into these capillaries (amino acids and
carbohydrates) and lacteals (lipids).
The material that remains undigested and unabsorbed
passes into the large intestine.
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Absorption of the majority of nutrients takes place in the
jejunum, with the following notable exceptions:
◦ Iron is absorbed in the duodenum.
◦ Vitamin B12 and bile salts are absorbed in the terminal ileum.
◦ Water and lipids are absorbed by passive diffusion throughout
the small intestine.
◦ Sodium bicarbonate is absorbed by active transport and
glucose and amino acid co-transport.
◦ Fructose is absorbed by facilitated diffusion
3. Immunological
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The small intestine supports the body's immune system.
◦ The presence of probiotic gut flora appear to contribute
positively to the host's immune system.
◦ Peyer's patches, located within the ileum of the small intestine
are an important part of the digestive tract's local immune
system.
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The large intestine, also called the colon or the large
bowel, is the last part of the digestive system in
vertebrates.
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Water is absorbed here and the remaining waste material is
stored as feces before being removed by defecation.
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It is the combination of the cecum, colon proper, rectum
and anal canal.
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In humans, it begins in the right iliac region of the pelvis,
just at or below the waist, where it is joined to the end of
the small intestine
It then continues up the abdomen, across the width of the
abdominal cavity, and then down to its endpoint at the
anus.
Overall, in humans, the large intestine is about 1.55 metres
(4.9 ft) long, which is about one-fifth of the whole length
of the gastrointestinal tract.
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The length of the adult human colon is, on
average, for women 155 cm (61in) range of
80 to 214 cm (31.5 – 84) and for men
166 cm (65in) range of 80 to 313 cm (31.5 –
123in).
The colon is the last part of the digestive
system in most vertebrates.
◦ It extracts water and salt from solid wastes before
they are eliminated from the body
◦ is the site in which flora-aided (largely bacterial)
fermentation of unabsorbed material occurs.
◦ About 1.5 litres or 45 ounces of water arrives in
the colon each day.
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The parts of the large intestine are either
intraperitoneal or behind it – retroperitoneum
which have no a complete covering of
peritoneum, so they are fixed in location.
Sections of the large intestine are:
The cecum and the appendix
◦ The cecum is the first section of the colon and
involved in the digestion
◦ the appendix which develops embryologically from
it, is a vestigial organ and has a high concentration
of lymphatic cells. Is not involved in digestion but is
part of the gut-associated lymphoid tissue.
 Also the appendix has a role in housing a sample of
the colon's microflora, and is able to help to
repopulate the colon with bacteria if the microflora
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Fig: Large intestine.
The ascending colon:
◦ The ascending colon is one part of four sections of
the large intestine. It runs through the abdominal
cavity, upwards toward the transverse colon for
approximately eight inches (20 cm).
◦ Its main functions of the colon is to remove the
water and other key nutrients from waste material
and recycle it back into the body
The transverse colon:
◦ is the part of the colon from the hepatic colic
flexure to the splenic flexure.
◦ It hangs off the stomach, attached to it by a large
fold of peritoneum called the greater omentum
◦ It is connected to the posterior abdominal wall by a
mesentery known as the transverse mesocolon
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It functions as to concentrate materials in
large intestine as the contents become more
solid (water is removed) in order to form
feces.
Blood supply is from middle colic artery [a
branch of the superior mesenteric artery
(SMA)] to its proximal two-thirds
while the latter third is supplied by branches
of the inferior mesenteric artery (IMA).
The "watershed" area between these two
blood supplies, which represents the
embryologic division between the midgut and
hindgut, is an area sensitive to ischemia.
The descending colon:
 The descending colon is the part of the colon from
the splenic flexure to the beginning of the sigmoid
colon.
 It is retroperitoneal in two-thirds of humans with a
(usually short) mesentery.
 One function of the descending colon in the digestive
system is to store faeces that will be emptied into the
rectum.
 Blood supply: The arterial supply comes via the left
colic and sigmoid branches of the inferior mesenteric
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artery.
Veins follow artery and drain into the inferior
mesenteriv vein
Nerve supply: sympathetic and parasympathetic
pelvic splachnic nerve through the inferior mesenteric
plexus.
The sigmoid colon – the v-shaped region of
the large intestine.
 Is the part of the large intestine after the
descending colon and before the rectum.
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The walls of the sigmoid colon are
muscular, and contract to increase the
pressure inside the colon, causing the stool
to move into the rectum.
Blood supply: supplied with blood from
several branches (usually between 2 and 6)
of the sigmoid arteries, a branch of the IMA.
The IMA terminates as the superior rectal
artery.
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Rectum is the last section of the colon. ( ref
to perineum)
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Additional appearances:
◦ Taeniae coli – three bands of smooth muscle, run
the length of the large intestine
◦ Haustra – bulges caused by contraction of taeniae
coli, Because the taenia coli are shorter than the
large bowel itself, the colon becomes sacculated,
forming the haustra of the colon which are the
shelf-like intraluminal projections.
◦ Epiploic appendages – small fat accumulations or
tabs on the viscera.