endo

HideShow resource information
  • Created by: jo bill
  • Created on: 22-12-14 14:26

diabete mellitus

  • colection of diseases of glucose homeostasis
  1. type 1 diabetes
  2. types 2 diabetes
  3. MODY
  4. gestational diabetes
  5. T2DMY
  • accounts for 10% of NHS budget
  • associated with serous complications
  • shortens lifespan/accelerates ageing

classification

Type 1 diabtetes

  • immune mediated 
  • idiopathis
  • formerly insulin-dependent diabtetes

Type 2 diabtetes

  • insulin resistance with inadequate insulin secretion
  • formely non-insulin dependent diabtetes

seondary diabetes

  • diabetes secondary to pancreatic diabetes
  1. chronic pancreatitis
  2. haemochromatosis
  3. pancreatic surgery or trauma
  4. cystic fibrosis
  • diabetes secondary to drugs and chemicals
  1. glucocorticoids
  2. diuretics
  3. antipsychotics
  4. B-blockers
  • diabetes secondary to genetic abnormalities
  1. genetic deffects of B-cell function
  2. gentic disorders of insulin action
  • infections
  1. congenital rubella
  2. cytomegalovirus
  3. mumps
  • gestational diabetes

normal glucose homeostasis

Post- prandialy

  • glucose comes from GI tract via SGLT1
  • glucose stimulates insulin release from pancreatic-beta cells
  • insulin promotes glucose uptake in hepatocytes, skeletal muscle and adipocytes

fasting state

  • glucose drops- lowering insulin
  • catabolism occurs

insulin secretion

insulin is produced by pancreatic beta-cells

  • 51aa peptide comprising 2 chains
  • synthesised on RER as pre-proinsulin 
  • signal peptide remoed before transfer to golgi
  • cleaved by PC1/3 to form mature insulin
  • stored in secretory granules

insulin release

  • nutrient response - biphasic pattern
  • basal secretion does occur
  • catabolism occurs

sequence of reactions

  1. amino acids, transfer -RNA, ATP,GTP,Mg2+, etc
  2. pre-proinsulin synthesis
  3. proinsulin transfer
  4. packaging in vesicles containing membrane-bound proteases
  5. +zn2+ and release of Arg, Lys
  6. conversion of pro-insulin to insulin
  7. crstalloid zinc-insulin core surrounded by C-peptide
  8. Ca2+ and energy-dependent secretion of insulin and C-peptide

increased by:

  • nutrients - raised glucose, amino acids
  • hormones- glucagon, gastrin, secretin, cholecystokinin, GIP, GLP-1
  • pancreatic innervation -signalling via sympathetic, parasympathetic
  • insulin -> phosphorylation of…

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all diabetes resources »