Pancreas Flashcards
Two functions of the pancreas?
Exocrine: Secretion of digestive enzymes
Endocrine: secretion of insulin and glucagon and other hromones
Which region of the pancreass are hormones secreted from?
Islets of langerhans
Give the normal, after meal and renal threshold values for plasma glucose?
normal: 3-6mmol/L
After meal- 7-8mmol/L
renal threshold- 10mmol/L
Where is insulin secreted in the pancreas? Describe the process of insulin secretion
pancreatic β cells
Process:
preproinsulin made–>ER–>cleaved to proinsulin–>taken to the golgi–>packaged into the vesicles for exocytosis–>cleaved into C-peptide and insulin–>on stimulation by Ca2+ insulin leaves the cell with C peptide
How is the releave of insulin regulated?
With high ATP levels, the K+ATP channels get inhibited so that less K+ leaves the cell. So the cell membrane depolarises–>Ca2+ channels opening–>Ca2+ influx–>insulin release
three ‘anti’ actions of insulin?
antigluconeogenic
antiglycogenetic
antilipolytic
At a cellular level, how does insulin lead to the uptake of glucose?
cause GLUT4 transporter to move to the cell surface
so glucose moves into cells
Describe briefly the cell surface receptor insulin binds to
alpha chain on the exterior
β chain spans the cell membrane
Describe 4 metabolic effects of insulin
increased glycogen synthesis
increased TAG storage
inhibits FA release into the blood
increased Amino Acid uptake into cells for increased protein synthesis
WHat cells in the pancreas secrete glucagon?
alpha cells
3 effects of glucagon?
lipolytic
glycogenolytic
gluconeogenetic
How is glucagon synthesised in the alpha cells
in the RER
packaged in the golgi into granules
Margination-movement to the cell surface
exocytosis
Describe the half life of insulin and glucagon and why?
short
constant careful control of blood glucose levels
