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Pancreas (Diabeted Mellitus ("sweetened urine", Plasma glucose…
Pancreas
Diabeted Mellitus
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2 types:
- Type 1 - Insulin dependent, insulin production impaired, treated by insulin injections
- Type 2 - Non-insulin-dependent, insulin production normal but cells resistant to its effects
Hyperglycaemia, PU/PD (polyuria, polydipsia). Urine specific gravity normal/high due to glycosuria
Degradation of lipids increases leading to increased plasma FFA:
- Incomplete metabolism --> ketone bodies
- Some ketones are acidic --> metabolic acidosis --> impaired brain function/diabetic coma
Hypoglycaemia - Plasma glucose below normal range (5mmol), most often caused by isulin overdose/isulinoma, treated by oral/IV glucose
Actions of insulin
Above 5 mmol insulin secretion, below 5mmol glucagon secretion ish
Binds to receptors on target cells, receptor functions as a tyrosin kinase upon activation
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Increases conc/activity of intra-cellular enzymes involved in metabolism of glucose/amino acids/lipids:
- increases glycogenesis in liver/skeletal muscle
- increases formation of glycerol/ffa for tri-glyc synth
- inhibits enzymes that breakdown tri-glys
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Ionic composition
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- Bicarb actively transported into duct lumen n exchange for Cl-
- Water follows by osmosis, H+ correspondingly transported into blood stream
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At high flow rates not enough time, so panc juice high alkaline
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Comparative physiology
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Ruminants - Continuous flow of rumen contents into abomasum/SI, pancreatic juice secretion continuous
Carnivores/omnivores - Intermittent flow of stomach contents into SI - pancreatic juice secretion intermittent
Horse - Continuous flow of stomach contents, secretion continuous but increases after feeding
Functional anatomy
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Structure of endocrine panc consits of lots of isolated clumps of cells surrounding capillary (islets of Langerhands)
2 major functions: Digestion (exocrine), regulation of metabolism (endocrine)
Exocrine pancreas
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In horse/pig large amounts of pancreatic juice to create fermentation environment in large intestine
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Regulation of secretion
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Cephalic/gastric mediated by vagus/gastrin (carnivores; only enzymatic component, horse/pig - ionic component too)
Intestinal phase mediated by secretin/cck (causes largest increase in secretion, VIP [vasoactive inhibitory peptide] inhibits effect of secretin)
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Endocrine pancreas
Islets of Langerhands (clusters of cells throughout pancreatic tissue), 3 major types: alpha, beta, delta
Hormones: Insulin (beta), glucagon (alpha), somatostatin (delta) which inhibits insulin and glucagon secretion
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