Pancreas Flashcards
(100 cards)
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.