diabetes ch40 42
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FUNCTION/DYSFUNCTION
OF ENDOCRINE PANCREAS
Diabetes
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Anatomy of the pancreas:Both an exocrine and endocrine organ
Cells with exocrine function release analkaline fluid containing sodiumbicarbonate and enzymespancreatic duct
small intestinePancreatic juice aids in breakdown anddigestion of food in the small intestine
Pancreatic exocrine cells = acinar cells
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Endocrine Function :
Cells of the Islet of Langerhans synthesizeand release hormones into the circulation.
Hormones travel through the bloodstream to
target tissues (especially liver and muscle)At the target cells, hormones bind specificreceptors and cause cell changes that control
metabolism
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Pancreatic endocrine cells regulatecarbohydrate, fat, protein metabolism:
Alpha cells secrete the hormoneglucagon
Beta cells secrete the hormones
insulin and amylin Delta cells secrete the hormones
gastrin andsomatostatin
F cells - secrete hormone pancreaticpolypeptide
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Beta Cells
Synthesize pre-proinsulin, a proteinThis is cleaved by enzymesproinsulin, thencleaved again insulin
Insulin is the biologically active hormone thatis released into the bloodstream
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Insulin secretion is controlledthrough several mechanisms:
Chemically high levels of glucose andamino acids in the blood
Hormonally beta cells are sensitive toseveral hormones that may inhibit orcause insulin secretion
Neurally stimulation of theparasympathetic nervous system causesinsulin to be secreted.
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Insulin secretion is decreased by:
Decreased blood glucose concentration Increased blood insulin concentration Sympathetic stimulation
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Blood glucose is decreased becauseinsulin causes glucose to leave thebloodstream and enter the metabolizingcells.
With the exception of brain, liver and
erythrocytes, tissues require membraneglucose carriers.
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Modern classifications (Table17.7)Type 1 or IDDM - Insulin Dependent Diabetes
Mellitus
Type 2 or
NIDDM - Non-Insulin Dependent DiabetesMellitus
Other Types of Diabetes Mellitus
GDM - Gestational Diabetes Mellitus
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Accounts for 10% all DM in the Western world
~10-15% have parent or sibling with thedisease
Peak age of diagnosis = 12 years
Genetic/environmental/autoimmune factorsdestroy beta cells
Believed abrupt onset now immunomarkers andpreclinical symptoms have been discovered
Type 1 or IDDM
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Clinical Manifestations:Weight loss - Patient eats, but nutrients are
not taken up by the cells and/or are notmetabolized properly
Osmotic diuresis results in fluid loss
Loss of body tissue by metabolism of fatsand proteins
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NIDDM insulin resistance in target cells
See decreased cell responsiveness
Decreased insulin secreted by cellsAlso abnormal amount of glucagonsecreted
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Treatment :
provide glucose (I.V. or subcutaneous ifunconscious)
Observe for relapse
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Treatment:- low dose insulin
Also, administer fluids, electrolytes
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Microvascular disease chronic diabetesw/ improper glucose metabolism
thickening of the basement membrane ofcapillaries, particularly in the eye and thekidney. As the capillary changes in this
way, Decreased tissue perfusionSo ischemia hypoxia
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In the eye the retina is metabolically quite active,so hypoxia here is a big problem
So see:Retinal ischemia
Formation of microaneurisms, hemorrhage,
tissue infarct, formation of new vessels,retinal detachment
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