Blood glucose homeostasis Flashcards
Define a paracrine cell
A source cell releases its signalling molecules to the next cell
Define an autocrine cell
Releases its signalling molecule to itself (same cell)
What is endocrine signalling?
Cells release signalling molecules into circulation/blood stream
How many lobes pertain to the pancreas and where are these lobes situated?
2
- right lobe within meso-duodenum
- left lobe within greater omentum
Is the pancreas an exocrine or endocrine gland?
Both
Some products are released into ducts and some into the bloodstream
Within the pancreas what are groups of exocrine cells arranged in?
What do they produce?
Clusters called acini
- produce digestive enzymes
Within an islet (endocrine tissue) what are the 4 types of endocrine cell?
- alpha cell
- beta cell
- delta cell
- f cell
How is proinsulin converted to active insulin?
Removal of inactive peptide water soluble polypeptide
What is the primary driver for insulin secretion?
An increase in blood [glucose], detected by beta cells
What other mechanisms further control insulin?
- GI hormones
- Parasympathetic activity
- Sympathetic activity
- increase in plasma amino acids after a meal
How does insulin move in and out of cells?
Not lipid soluble so moves through specific protein channels (GLUT transporters)
Name some cells that do not require insulin to take glucose into their cells?
Brain
Mammary gland
GI tract
Kidney tubules
What is the role of the liver is maintaining glucose levels?
- important in taking excess glucose out of blood returning from the gut
- The liver’s glucose transporter, GLUT 2, is always present in the cell membrane and can transport in either direction, depending on the concentration gradient
What is the level of glucose in the CSF of the CNS directly proportional to?
Blood sugar
What is the overall effect of increased insulin?
Increased stores of glycogen, fat and protein
