Endocrine/Repro Flashcards
define endocrine
the source cell sends out a signal molecule/hormone that acts on a specific receptor
define autocrine
an autocrine cells releases a signalling molecule/hormones that acts on autocrine receptors on the cell that released the hormone
define paracrine
a cell signalling molecule/hormone released by a paracrine cell acts on a nearby target cell
local action
examples are renal autoregulation and neuromuscular junctions
define endocrine systems
an endocrine cell releases the cell signalling molecule that circulates through the blood to a distant target cell
what are endocrine glands?
a collection of glands that secrete hormones directly into the circulatory system to be carries toward a distant target
where is the right lobe of the pancreas found?
within the meso-duodenum
where is the left lobe of the pancreas found?
within a deep leaf of the greater omentum
is the pancreas an endocrine or exocrine gland?
both
what are the clusters of exocrine cells in the pancreas called?
acini
what are acini?
clusters of exocrine cells in the pancreas
what do acini produce?
digestive enzymes that flow through ducts into the GI tract
what are islets of Langerhans?
areas/clusters of endocrine tissue distributed among the exocrine tissue of the pancreas
what are the four types of endocrine cell in an islet of Langerhans and what do they do?
alpha cell- secretes glucagon
beta cell- secretes insulin
delta cell- secretes somatostatin
F cell- secretes pancreatic polypeptide
how is insulin produces and released?
beta cells synthesise pro-hormone called PROINSULIN
converted to active insulin by removal of inactive peptide water soluble polypeptide
binds to specific tyrosine kinase membrane receptor
what is the primary control of insulin secretion?
an increase in blood glucose concentration
where is blood glucose concentration detected?
by beta cells in the islets of Langerhans
what are the four further ways of controlling insulin?
GI hormones in feed-forward mechanism - anticipatory release of insulin before a meal
Parasympathetic activity - increase during and after a meal
Sympathetic activity - decreases insulin activity
Increase in plasma amino acids after a meal - increases insulin secretion
how does glucose move in and out of cells?
moves through specific protein channels called GLUT transporters
insulin increases the expression og GLUT 4 transporters
do all cells require insulin in order to take glucose into the cell?
no
cellular uptake of glucose is independent of insulin the brain (through GLUT 3) and mammary glands, GI tract and kidney tubules through secondary active transport with sodium
when is insulin the dominant hormone? is it anabolic or catabolic?
dominant in a fed state
anabolic
when is glucagon the dominant hormone? is it anabolic or catabolic?
dominant in the fasted state
catabolic
how does the liver respond to insulin?
Respond to insulin by increasing uptake of glucose via insertion of GLUT 4 transporters in their cell membrane within seconds.
No transporters = no glucose uptake so these cells will be starved of energy if there is insufficient insulin.
Glucose converted to glucose-6-phosphate, glycogen or fat.
what does a decrease in blood glucose concentration result in i the hepatocytes?
hepatocytes make glucose and transport out into the blood using GLUT 2 transporters
detected by beta cells in the pancreas, leads to a decrease in insulin in the plasma
what does an increase in the blood glucose concentration lead to in the hepatocytes?
increased glucose in the plasma, detected by beta cells, increased insulin in the plasma
glucose concentration reverses and glucose enters the hepatocytes using GLUT 2 transporter. Insulin stimulates hexokinase to maintain a low intracellular concentration of glucose.
