small intestine- Pylorus to ileocecal junction, Length - 6m, Diameter- 2.5- 3 cm
Part- 3 1-Duodenum- 20-25cm, 2-Jejunum- 2/5th (2.5 m), 3-Ileum- 3/5th (3m)
Small Intestine Wall-
a- Serosa Coat- Peritoneum layer
b- Muscular Coat- Outer-long, inner- circular
c-Submucosa Coat- Connective tissue, venous plexus
d- Mucosa Coat- Villi present
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1- Duodenum- C-shaped, 20-25 cm long
Duodenal gland(Brunner's gland)- Produce mucous rich alkaline secretion containing bicarbonate.
Receives bile juice & Pancreatic juice through the Pancreatic Duct, controlled by the sphincter of Oddi.
Arterial supply-
Superior Pancreaticoduodenal artery, Inferior Pancreaticoduodenal artery
Venous Drainage-
Sup. Mesenteric vein, Portal vein, Splenic vein, Pancreaticoduodenal vein
2. Jejunum- 2.5 m long, Plicae & Villi present- increase its surface area
Work- product of digestion (Sugar, Amino acids & fatty acid) are absorbed into blood stream here
3. ileum- 3m length, Absorb mainly vit B12 & bile acid.
Mesentery- Broad fan shaped fold of peritoneum suspends jejunum & ileum from post abdominal wall convey nutrition & innervation
Blood supply- ileum & jejunum
Arterial Supply- Superior mesenteric artery, ileocolic artery
Venous Drainage- Superior mesenteric vein, ileocolic vein
Intestinal Gland- Secrete- Digestive enzyme & mucus
Simple Tubular glands- Present in Mucous mem. of the jejunum & ileum. Open b/w villi.
cell types-
1- Enterocytes cells- Absorptive
2- Goblet cells- secret mucus
3- Entero-endocrine cells- secret hormone CCK
4- Paneth cells- secret lysozyme, tumour necrosis factor
Functions of SI-
Peristalsis- increased by parasympathetic stimulations.
Secretion of intestinal juice- increased by PSS.
Secretion of hormone CCK & Secretin.
Absorption of nutrients.
Completion of chemical digestion of carbohydrate, protein, fat in the enterocytes of the villi.
Protection against infection of microbes.
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20 окт 2024
