The Endocrine Pancreas Pancreatic Anatomy Pancreas Head of Pancreas Neck of Pancreas
Celia, Frank, Contributing Writer has reference to this Academic Journal, PHwiki organized this Journal The Endocrine Pancreas Regulation of Carbohydrate Metabolism Pancreatic Anatomy Gl in addition to with both exocrine in addition to endocrine functions 15-25 cm long 60-100 g Location: retro-peritoneum, 2nd lumbar vertebral level Extends in an oblique, transverse position Parts of pancreas: head, neck, body in addition to tail Pancreas
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Head of Pancreas Includes uncinate process Flattened structure, 2 3 cm thick Attached to the 2nd in addition to 3rd portions of duodenum on the right Emerges into neck on the left Border b/w head in addition to neck is determined by GDA insertion SPDA in addition to IPDA anastamose between the duodenum in addition to the right lateral border Neck of Pancreas 2.5 cm in length Straddles SMV in addition to PV Antero-superior surface supports the pylorus Superior mesenteric vessels emerge from the inferior border Posteriorly, SMV in addition to splenic vein confluence to as long as m portal vein Posteriorly, mostly no branches to pancreas Body of Pancreas Elongated, long structure Anterior surface, separated from stomach by lesser sac Posterior surface, related to aorta, lt. adrenal gl in addition to , lt. renal vessels in addition to upper 1/3rd of lt. kidney Splenic vein runs embedded in the post. Surface Inferior surface is covered by transverse mesocolon
Tail of Pancreas Narrow, short segment Lies at the level of the 12th thoracic vertebra Ends within the splenic hilum Lies in the splenophrenic ligament Anteriorly, related to splenic flexure of colon May be injured during splenectomy (fistula) Pancreatic Duct Main duct (Wirsung) runs the entire length of pancreas Joins CBD at the ampulla of Vater 2 4 mm in diameter, 20 secondary branches Ductal pressure is 15 30 mm Hg (vs. 7 17 in CBD) thus preventing damage to panc. duct Lesser duct (Santorini) drains superior portion of head in addition to empties separately into 2nd portion of duodenum Arterial Supply of Pancreas Variety of major arterial sources (celiac, SMA in addition to splenic) Celiac Common Hepatic Artery Gastroduodenal Artery Superior pancreaticoduodenal artery which divides into anterior in addition to posterior branches SMA Inferior pancreaticoduodenal artery which divides into anterior in addition to posterior branches
Arterial Supply of Pancreas Anterior collateral arcade between anterosuperior in addition to anteroinferior PDA Posterior collateral arcade between posterosuperior in addition to posteroinferior PDA Body in addition to tail supplied by splenic artery by about 10 branches Three biggest branches are Dorsal pancreatic artery Pancreatica Magna (midportion of body) Caudal pancreatic artery (tail) Pancreatic Arterial Supply Venous Drainage of Pancreas Follows arterial supply Anterior in addition to posterior arcades drain head in addition to the body Splenic vein drains the body in addition to tail Major drainage areas are Suprapancreatic PV Retropancreatic PV Splenic vein Infrapancreatic SMV Ultimately, into portal vein
Venous Drainage of the Pancreas Lymphatic Drainage Rich periacinar network that drain into 5 nodal groups Superior nodes Anterior nodes Inferior nodes Posterior PD nodes Splenic nodes Innervation of Pancreas Sympathetic fibers from the splanchnic nerves Parasympathetic fibers from the vagus Both give rise to intrapancreatic periacinar plexuses Parasympathetic fibers stimulate both exocrine in addition to endocrine secretion Sympathetic fibers have a predominantly inhibitory effect
Innervation of Pancreas Peptidergic neurons that secrete amines in addition to peptides (somatostatin, vasoactive intestinal peptide, calcitonin gene-related peptide, in addition to galanin Rich afferent sensory fiber network Ganglionectomy or celiac ganglion blockade interrupt these somatic fibers (pancreatic pain) Pancreatic Hormones, Insulin in addition to Glucagon, Regulate Metabolism Production of Pancreatic Hormones by Three Cell Types Alpha cells produce glucagon. Beta cells produce insulin. Delta cells produce somatostatin.
Islet of Langerhans Cross-section Three cell types are present, A (glucagon secretion), B (Insulin secretion) in addition to D (Somatostatin secretion) A in addition to D cells are located around the perimeter while B cells are located in the interior Venous return containing insulin flows by the A cells on its way out of the islets Pancreatic Hormones, Insulin in addition to Glucagon, Regulate Metabolism Figure 22-8: Metabolism is controlled by insulin in addition to glucagon Structure of Insulin Insulin is a polypeptide hormone, composed of two chains (A in addition to B) BOTH chains are derived from proinsulin, a prohormone. The two chains are joined by disulfide bonds.
Roles of Insulin Acts on tissues (especially liver, skeletal muscle, adipose) to increase uptake of glucose in addition to amino acids. – without insulin, most tissues do not take in glucose in addition to amino acids well (except brain). Increases glycogen production (glucose storage) in the liver in addition to muscle. Stimulates lipid synthesis from free fatty acids in addition to triglycerides in adipose tissue. Also stimulates potassium uptake by cells (role in potassium homeostasis). The Insulin Receptor The insulin receptor is composed of two subunits, in addition to has intrinsic tyrosine kinase activity. Activation of the receptor results in a cascade of phosphorylation events: Specific Targets of Insulin Action: Carbohydrates Activation of glycogen synthetase. Converts glucose to glycogen. Inhibition of phosphoenolpyruvate carboxykinase. Inhibits gluconeogenesis. Increased activity of glucose transporters. Moves glucose into cells.
Specific Targets of Insulin Action: Lipids Activation of acetyl CoA carboxylase. Stimulates production of free fatty acids from acetyl CoA. Activation of lipoprotein lipase (increases breakdown of triacylglycerol in the circulation). Fatty acids are then taken up by adipocytes, in addition to triacylglycerol is made in addition to stored in the cell. Regulation of Insulin Release Major stimulus: increased blood glucose levels – after a meal, blood glucose increases – in response to increased glucose, insulin is released – insulin causes uptake of glucose into tissues, so blood glucose levels decrease. – insulin levels decline as blood glucose declines Insulin Action on Cells: Dominates in Fed State Metabolism glucose uptake in most cells (not active muscle) glucose use in addition to storage protein synthesis fat synthesis
Insulin Action on Cells: Dominates in Fed State Metabolism Insulin: Summary in addition to Control Reflex Loop Other Factors Regulating Insulin Release Amino acids stimulate insulin release (increased uptake into cells, increased protein synthesis). Keto acids stimulate insulin release (increased glucose uptake to prevent lipid in addition to protein utilization). Insulin release is inhibited by stress-induced increase in adrenal epinephrine – epinephrine binds to alpha adrenergic receptors on beta cells – maintains blood glucose levels Glucagon stimulates insulin secretion (glucagon has opposite actions).
Metabolic Regulation Anabolic effects of insulin are antagonized by the hormones of the adrenals, thyroid, in addition to anterior pituitary. Insulin, T3, in addition to GH can act synergistically to stimulate protein synthesis.
Celia, Frank Contributing Writer
Celia, Frank is from United States and they belong to AllAboutVision.com and they are from La Jolla, United States got related to this Particular Journal. and Celia, Frank deal with the subjects like Ophthalmology and Opticians
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