pancreatic physiology Flashcards
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
