Pancreas Flashcards
Match each pancreatic hormone with the cell type that produces it:
1.) Pancreatic polypeptide
2.) Glucagon
3.) Somatostatin
4.) Insulin
A.) Beta cells
B.) Alpha cells
C.) Delta cells
D.) PP cells
Pancreatic peptide: PP cells
Glucagon: Alpha cells
Somatostatin: Delta cells
Insulin: Beta cells
What are Acini glands, and what are they responsible for?
-secrete digestive juices into the duodenum
What are Acinar cells?
Make up the exocrine portion of the pancreas and accounts for 98% of the gland’s weight.
Gastrointestinal enzymes and bicarb are synthesized in the acinar cells and secreted into the pancreatic ducts to aid in digestion
What do the Islets of Langerhans do?
Make up the endocrine portion of the pancreas
-produce hormones that do not enter ducts but secrete directly into capillary blood vessels.
What cell type makes up the largest portion of the islet?
Beta cells (60%)
Beta cells also secrete amylin
What is somatostatin?
type of inhibitory hormone produced from the hypothalamus that may restrict the rate at which nutrients are absorbed after a meal
Inhibits insulin and glucagon. It also inhibits the splanchnic blood flow, gastric motility and gallbladder contraction.
AKA growth hormone-inhibiting hormone., regulates hormone output from the islet cells.
What does pancreatic polypeptide do?
Inhibits pancreas’ exocrine function
inhibits pancreatic exocrine secretion, gallbladder contraction, gastric acid secretion and gastric motility
Define glycogenesis
storage of glucose as glycogen in liver and muscle
Define lipogenesis
Formation and storage of fat as triglycerides, occurs in adipose tissue
Define gluconeogenesis
Formation of glucose from lactate, pyruvate, amino acids, and glycerol.
-important hepatic glucose production mechanism during fasting and starvation
Define Glycogenolysis
the breakdown of glycogen into glucose- occurs primarily in the liver
Define Lipolysis
the breakdown of stored triglycerides to free fatty acids and glycerol- stimulated by the enzyme hormone-sensitive lipase
Glucagon in high concentrations also causes what?
1.) relaxation of bile ducts and promotes bile flow
2.) enhances cardiac contraction
Exocrine hormones are secreted into the ________ for digestion
Duodenum
Endocrine hormones are secreted into the ______ _______ for metabolism
systemic circulation
What stimulates insulin release from pancreatic beta cells?
-High blood glucose (plasma glucose is by far the most important regulator of insulin release from the beta cells)
-amino acids
-beta-keto acids
-acetylcholine (parasympathetic stimulation)
-gastrointestinal hormones
-beta agonists
What inhibits insulin secretion?
-Low blood glucose
-fasting (80 mg/dL)
-glucagon
-cortisol
-catecholamines (alpha-agonists)
-growth hormone
-somatostatin
What cells/organs do not need insulin to utilize glucose?
BRAIN
-erythrocytes
-retina
-epithelium
-gonads
-liver
Cerebral function generally declines when serum glucose falls below what level?
50 mg/dL
What effects on the heart does glucagon produce?
-increased myocardial contractility
-increased heart rate
-increased AV conduction
by increasing the intracellular concentration of cAMP. This occurs independently of ANS function
What is the main function of insulin?
Insulin is an anabolic hormone that promotes energy storage.
It works in all cells, but especially in the liver, adipose, and muscle beds.
How is insulin eliminated?
-Insulinase degrades unused insulin in the liver, with some degraded by the kidneys and muscles
-circulates almost entirely unbound w plasma half-life of 5-7 mins
After a meal, insulin secretion increases and plays a significant role in capturing and storing energy. How is this accomplished?
-Increasing glucose permeability in skeletal muscle, live, and fat
-converts carbs to glycogen in the liver and skeletal muscle
-converts excess carbs to fats. These fats can be oxidized if blood sugar becomes low
-Promoting cellular uptake of amino acids, potassium, magnesium and phosphate.
-Encouraging protein synthesis and discouraging protein breakdown
-Stimulating the Na/K-ATPase. (This decreases serum potassium and is why we give insulin and D50 for hyperkalemia)
Describe the insulin receptor:
Consists of 2 alpha and 2 beta subunits that are joined together by disulfide bonds.
When insulin binds to the receptor, the beta subunits activate tyrosine kinase, which then activates insulin receptor substrates (IRS). The insulin cascade turns on the GLUT4 transporter, which increases glucose uptake by skeletal muscle and fat.
What does glucagon do?
-Hormone of energy release
-glucagon is a catabolic hormone that promotes energy release from adipose tissue and the liver.
-Enhance hepatic glucose output (glycogenolysis and gluconeogenesis)
-it a physiologic antagonist to insulin
How is glucagon eliminated?
eliminated by the kidneys and liver and has a half-life of 3-6 minutes
What does glucagon in high concentrations cause?
1.) relaxation of bile ducts and promotes bile flow
2.) enhances cardiac contraction
What stimulates glucagon release?
-Hypoglycemia
-amino acids
-beta-adrenergic stimulation
-exercise
-cholecystokinin
-gastrin
-cortisol
-surgery/stress/trauma/sepsis
What inhibits glucagon release?
-High glucose levels
-somatostatin
-free fatty acids
-ketones
-insulin
What are other uses for glucagon? (IV 1-5mg)
-beta-blocker overdose
-CHF
-Low cardiac output after MI or CPB
-improving MAP during anaphylaxis
-also administered during ERCP to relax the biliary sphincter
(N/V are key side effects of glucagon)
Compared to type 1 diabetes mellitus, choose the statements that MOST accurately describe type 2 diabetes mellitus (select 2)
a.) peripheral sensitivity to insulin is reduced
b.) it is more likely to cause hyperglycemic hyperosmolar syndrome
c.) it is usually associated w a thin body habitus
d.) it is usually caused by an autoimmune response
a.) peripheral sensitivity to insulin is reduced
b.) it is more likely to cause hyperglycemic hyperosmolar syndrome
Diabetes shifts metabolism towards:
protein catabolism and lipid oxidation
-insulin deficiency produces a shift from carbohydrate to fat metabolism
-free fatty acids become main energy substrate for essentially all tissues
What is the diagnostic criteria for diabetes?
-Fasting plasma glucose >126 mg/dL
-random glucose level > 200 mg/dL + classic symptoms
-Two hour plasma glucose > 200mg/dL during an oral glucose tolerance test
-Hemoglobin A1C >6.5%
pre-diabetes: FPG 100-125
fasting defines as no caloric intake for at least 8 hrs.
At what blood glucose levels will you see glucosuria?
When blood glucose concentration increases to approx 180mg/dL, the amount of glucose filtered at the kidney glomerulus cannot be totally reabsorbed.
-Excess glucose spills into urine (glucosuria) and acts as osmotic diuretic
Causes of DM type 1
causes:
-autoimmune
-genetic
-virus
Causes of DM type 2
Obesity
What is the typical BG in diabetic ketoacidosis?
> 250 mg/dL
-Usually occurs in type 1
At what blood glucose level does insulin begin to be released?
100 mg/dL
At what blood glucose level is insulin’s max response?
400-600 mg/dL
At what blood glucose level is insulin’s max response?
400-600 mg/dL