ENDOCRINOLOGY (pancreas)

ENDOCRINOLOGY (pancreas)

1. Pancreas

   • The pancreas has both endocrine and exocrine funtions
     • The islets of Lngerhans include alpha cells, beta cells and delta cells
       • Alpha cells secrete glucagon
         • More predominant effect than insulin
         • Increased by sympathetic signals, adrenaline secretion and decreased plasma glucose
         • Effects on the liver include increased gluconeogenesis and increased protein breakdown. Causes increased lipolysis in adipose tissue
         • Glucagon secreted in the post-absorptive/ catabolic state when energy stores are metabolised
       • Delta cells secrete somatostatin
       • Beta cells secrete insulin
         • Increased by parasympathetic signalling, increased plasma glucose and amino acid levels
         • Insulin dominates in absorptive/ anabolic state. This is the period just after eating when energy is stored in macromolecules
         • Effects on the liver include decreased gluconeogenesis and increased triglyceride synthesis. In the muscle it causes increased glycogen synthesis and decreased glycogenolysis. Also decreased lipolysis in adipose tissue
           • Increased glucose uptake by GLUT4 transporter translocation
     • Secretes digestive enzymes from acini
   • Normal blood glucose = 70-140mg/dl
     • Hypoglycaemia
       • Symptoms include sweating, pounding heart, shaking, confusion, visual disturbance
       • Treated with oral or IV glucose or glucagon
     • Hyperglycaemia
       • Type 2 - insulin resistance at target tissue or impaired insulin secretion
         • Firstly managed by lifestyle factor changes
         • Drug treatments include sulphonylureas that increase insulin secretion, thiazolidinediones (TZD's) that reduce insulin resistance, as do biguanides (Metformin)
           • Sulphonylureas block K+ ATP channels so cause depolarisation and therefore release of insulin
           • TZD's bind to PPAP-y receptors; more GLUT4 transporters
         • Orlistat can be taken to reduce weight
         • Long term complications
           • Diabetic nephropathy - end stage renal failure needs transplant
           • Diabetic neuropathy - nerve conduction velocity slowed to lower limbs. Effects sensation to pain
           • Diabetic retinopathy - increases cataracts due to thickened membrane of retinal blood vessels
       • Type 1 - beta cell destruction so inability to produce insulin
         • Autoimmune destruction of beta cells
         • Treated by mimicking exogenous insulin administered subcutaneously around meal times
           • Can be short acting (Ispro), delayed (Lente) or long acting (Ultralene')
       • Diagnosed by: 1.symptoms 2. random plasma glucose >200mg/dl 3.fasting plasma glucose >126mg/dl 4. Oral glucose tolerance test >200mg/dl after 2hours

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