Pancreas Flashcards
What is the term for islands of endocrine cells within exocrine tissue?
Islets of langerhands
(secrete digestive enzymes)
What do the following cells secrete?
𝛃 cells (60% of endocrine cells)
𝛂 cells (25% of endocrine cells)
𝛅 cells
𝛄 cells
𝝐 cells
𝛃 cells = Insulin, Amylin
𝛂 cells = Glucagon
𝛅 cells = Somatostatin
𝛄 cells = Pancreatic polypeptide
𝝐 cells = Ghrelin
What hormones inhibit digestive function/ suppress appetite?
Amylin (acts on CNS, suppresses appetite)
Somatostatin (inhibits digestive function)
Pancreatic polypeptide (reduces appetite/ food intake)
What is the role of Ghrelin?
Appetite stimulating
Preproinsulin is converted to proinsulin which is cleaved in the granules to what?
Insulin + C-peptide (1:1 ratio)
(C-peptide is more reliable measurement for assessing insulin use in DM pts due to longer half life)
Glucose stimulates insulin release via what process in beta cells?
Excitation-secretion coupling
What is necessary for the facilitated diffusion of glucose across cell membranes?
GLUT2
In the process of insulin release, glucose and PO4 yield glucose-6-phosphate which is then oxidized to form what?
ATP
What is the role of ATP in the release of insulin?
Closes K+ channels = decreased K+ depolarizes cell membrane
(This leads to voltage- gated Ca channels opening and Ca entering the cell)
In the insulin release process, once Ca enters the beta cells, what does this trigger?
Triggers exocytosis of insulin vesicles = insulin secreted into circulation
What are the 3 primary effects of insulin?
- Affect energy stores
- Recruits GLUT-4 to cell surface
- Stimulates MAP kinase pathways
Excess insulin can lead to hypoglycemia which can then ultimately lead to what?
Depressed brain function/ LOC
How does insulin affect energy storage in carbs, lipids, and proteins?
Promotes storage
(decreases blood glucose, fatty acids, and AAs)
In what tissues does the insulin dependent transporter GLUT-4 exist?
Adipose and resting muscle cells
Where are GLUT 1, 2, and 3 proteins located?
GLUT1 = BBB
GLUT2= kidney/ intestine
GLUT3= neurons
How do you treat an insulin OD?
Exogenous sugar
……. or should i say……. a sugary snack
How do you treat reactive hypoglycemia (beta cells release too must insulin in response to glucose)?
Control by limit of dietary cards, DO NOT treat with exogenous sugar
What is the most common endocrine disorder?
DM = high blood surgar levels over a prolonged period
What is the primary difference between T1 and T2 DM?
T1 is autoimmune (T-lymphocytes destroy beta cells = lack of insulin secretion)
T2 is non-insulin dependent (tissue resistant to insulin as a result of life-style choices)
What are the acute sxs of DM?
High blood glucose
What are the chronic sxs of DM? (4)
Retinopathy, neuropathy, nephropathy, CV disease
A value of what on fasting plasma glucose is concerning for DM?
> 126
(N = <110, borderline = 110-125)
Ingestion of 75mg of glucose within 5 min and measurement of blood glucose at 60 and 120 min is the protocol for what test?
Oral glucose tolerance test (OGTT)
What are considered normal values at 1 and 2 hours of the OGTT?
1 hour < 180
2 hours < 140
What is considered DM on a HbA1c test? (average glucose levels over 3 months)
DM > 6.5%
What tissues is glucagon expressed in?
Liver, intestine, brain, pancreas
Glycogen is converted to glucose via what?
(It stimulates gluconeogenesis and glycogenolysis in the liver and lipolysis in adipose tissue)
Glucagon
↑ glucose, somatostatin, insulin, fatty acids, keto acids leads to what?
Inhibition of glucagon
↓ glucose, epi (𝛃2), vagal stimulation, CCK, fasting, exercise, protein (in the absence of carbs) leads to what?
Stimulation of glucagon
Conversion of proglucagon to glucagon also yields what?
Incretin (GLP1)
When is GLP1 (incretin) released? And what does its release lead to?
Increased glucose levels in intestinal lumen
Results in increased insulin release from beta cells
Generally speaking, what is the affect of glucagon on energy stores?
Favors release
(increased blood glucose, fatty acids/ ketons, and AAs)
Glucagon has a minimal effect on what tissue?
Proteins
(it does increase blood AAs but has minimal effect and NO effect on skeletal muscle proteins, which is the major protein storage site)
What is the primary affect of somatostatin?
Inhibits release of insulin and glucagon
(binds to beta and alpha cells via SSTR2 receptor and leads to hyperpolarization of cells)
Somatostatin release is stimulated by high fat, carbs, and protein. This ultimately leads to what type of effect in the GI tract?
Inhibitory; prolonged duration of intestinal food absorption
How does somatostatin affect the release of GH?
Inhibits it
The CNS plays a role in the control of glucose because it has receptors for nutrient levels and hormones. Where specifically is glucose detected and what hormones does the CNS respond to?
Glucose detection in the arcuate nucleus
Hormones = insulin, leptin, GLP1
The hypothalamus regulates glucose homeostasis via insulin secretion but is blocked by what?
Alpha- adrenergic stimulation of SNS
What structure regulates the homeostasis of glucose via insulin secretion, glucose secretion, hepatic glucose output, and glucose uptake by skeletal muscles?
Hypothalamus
Neural control of glucose involves the control of energy balance via monitoring of what 2 things?
Food intake vs energy expenditure
(also control of body weight)
What are the orexigenic hormones?
Ghrelin
What are the anorexigenic hormones?
Leptin, insulin
What hormone favors release of energy stores during short term stress?
Epinephrine
What hormone favors release of energy stores during long term stress?
Cortisol (decreased glucose uptake in tissues other than the brain)
Epinephrine results in decreased insulin secretion via what?
Alpha-adrenergic stimulation of beta cells
What hormone is released during hypoglycemia, sleep, stress, and exercise, and has a small role in fuel metabolism?
Growth hormone
