pancreatic physiology Flashcards
(20 cards)
is the pancreas intra or retroperitonea;
retro
anatomy of pancreas
posterior to greater curvature of stomach
near c portion of duodenum
secretions pass into small intestine then two larger ducts
what are the largest proportion of cells called
acini 98-99%
exo and endocrine function of pancreas
Exo- acini
endo- islet cells , manufacture and release several peptide hormones
peptides secreted by the islets of langerhans and basic role
insulin - reduces glucose output by liver
glucagon - mobilises glucose, FA and AA
three types of cells in the islet of langerhans
alpha - glucagon
beta - insulin
delta - soma statin
Hormonal regulation of insulin
suppresses hepatic glucose output
increases glucose uptake into insulin sensitive tissues
supresses lipolysis, breakdown of muscle
WHAT is proinsulin
A blood test would measure pro insulin , a building block for insulin , to turn food into energy your pancreas makes pro insulin
Pro insulin is then made into insulin and c peptide
what does presensce of c peptide indicate
that your body is producing insulin
process of biphasic insulin release
B-cells sense rising glucose and aim to metabolise it
First phase response is rapid release of stored product
Second phase response is slower as it is the release of a newly synthesised hormone
What is the action of insulin
insulin binds to insulin receptor ,
this mobiles vesicles with GLUT 4 transporter
this vesicle binds to the plasma membrane and integrates itself glucose can enter the cell via GLUT4 transporter
what is involved in glucose sensing
Primary glucose sensors are in the pancreatic islets
Also in medulla, hypothalamus and carotid bodies
Inputs from eyes, nose, taste buds, gut all involved in regulating food
Sensory cells in gut wall also stimulate insulin release from pancreas - incretins
what are the incretins
Gut hormones that are secreted from enteroendocrine cells into the blood within minutes after eating
They help to regulate the amount of insulin that should be released
regulation of CHO metabolism
Breakdown of glycogen
Gluconeogenesis (utilises 3 carbon precursors to synthesise glucose including lactate, alanine and glycerol)
Glucose is delivered to insulin independent tissues, brain and red blood cells
Muscle uses FFA for fuel
low blood glucose response
stimulates release of glucagon
Glucagon acts on liver to:
Convert glycogen into glucose
Form glucose from lactic acid and amino acids
Glucose released from liver raises blood glucose to normal
If blood glucose continues to rise, hyperglycaemia inhibits release of glucagon
response to high blood glucose
stimulates release of insulin
Ia acts on various cells to:
Accelerate facilitated diffusion of glucose into cells
Speed conversion of glucose into glycogen
Increase uptake of amino acids and increase protein synthesis
Speed synthesis of fatty acids
Slow glycogenolysis and gluconeogenesis
Blood glucose levels fall
If blood glucose continues to fall, hypoglycaemia inhibits release of insulin
what is diabeties mellitus
A disorder of carbohydrate metabolism characterised by hyperglycaemia
Which hormone inhibits ghrh
Somatostatin
What is the mechanism of insulin secretion
Glucose moves into beta cells via GLUT2 channel
atp is made
Closure of atp sensitive potassium channels
Depolarisation of beta cell membrane
Opening of voltage gated calcium channels
Vesicles containing insulin fuse with the cell membrane
Action of insulin
Insulin binds to insulin receptors
Causes mobilisation of intracellular GLUT4 vesicles
GLUT4 vesicles integrate into the cell membrane ,
Increase rate of FD of glucose into cells
Thus decrease in blood glucose levels
