Endocrine Disorder 1/ Pancreatic Disorders Flashcards
What are is the pancreas composed of?
two anatomically discrete sets of cells and functions
What two types of cells make up the pancreas?
exocrine
endocrine
What is the source of insulin and glucagon in the pancreas?
endocrine pancreas
What cells make up the bulk of the pancreas?
exocrine
What is the role of the exocrine pancreas?
secrete digestive enzymes into ducts that drain via the pancreatic duct and the common bile duct into the duodenum
What is the exocrine pancreas?
glands lined with epithelial (acinar) cells
What is in the endocrine pancreas?
islet of langerhans
What is the purpose of endocrine pancreas?
insulin and glucagon
What other hormones are excreted by the endocrine pancreas?
amylin, somatostatin, pancreatic polypeptide
Where can tumors occur in the pancreas?
head of the pancreas
What are the three major types of cells in the islet of langerhans?
alpha cells
beta cells
delta
Why is the blood supply near the islet of langerhans?
since the islet of langerhans secrete insulin and glucagon the vasculature allows for immediate secretion into the blood stream
What is the size of the islet of langerhans?
0.3mm in diameter
How many islets of langerhans are in the human pnacreas?
1-2 million
What do alpha cells secrete?
glucagon
What do beta cells secrete?
insulin
What do delta cells secrete?
somatostatin
Why are the cells within the islet of langerhans located close together?
Their close proximity allows for a close negative feedback loop
insulin inhibits glucagon secretion, amylin inhibits insulin secretion, and somatostatin inhibits the secretion of both insulin and glucagon
What is an example of a positive feedback loop?
oxytoxin during birth
What results in insulin release?
carbohydrate ingestion
What does insulin do when excess amounts of carbohydrates are consumed?
increases to store carbohydrates as glycogen in the liver
What happens with the excess carbohydrates that can not be stored as glycogen?
They are converted under the stimulus of insulin into fats and stored in adipose tissue
Define glycogenolysis
breaking down glycogen to glucose in the liver
glycogen breaks down into glucose 1 phosphate and glucose with hepatocytes
Define Gluconeogenesis
utilizing fructose and galactose to glucose
glucose is synthesized from non-carbohydrate metabolites
What form does insulin circulate into the blood?
unbound
What is the plasma 1/2 life of insulin?
6 minutes
What enzyme degrades insulin and where?
insulinase in the liver
How does insulin facilitate glucose uptake?
enzyme linked receptor on target cells in varying tissues
When is glucagon secreted?
In response to decreased blood glucose levels
opposite of insulin
What is the function of glucagon?
increase blood glucose concentration
Examples of hyperglycemic hormones
cortisol
growth hormone
epinephrine
glucagon (stimulates glycogenolysis/ glyconeogenesis and inhibits glycolysis)
How much does glucagon increase the blood glucose in the blood in what amount of time?
1mcg/kg of glucagon can elevate the blood glucose concentration approximately 20mg/100ml of blood (25% increase) in about 20 minutes
What affects does glucagon have on the liver (2)?
breakdown of liver glycogen (glycogenolysis)
increased gluconeogenesis in the liver
What are four OTHER functions of glucagon?
enhances the strength of the heart (contractility)
increases BF to some tissues (esp. kidneys)
enhances bile secretion
inhibits gastric acid secretion
What is the half life of somatostatin?
3 minutes
Somatostatin has the same chemical substance as
growth hormone inhibitory hormone
What is is somatostain designed to do?
delay the time the body can absorb the nutrients in the stomach
extend the period over which the food nutrients are assimilated into the blood
What does somatostatin do in a variceal bleed?
it inhibits the secretions to decrease motility in the GI tract
When is somatostatin normally secreted?
ingestion of food stimulate secretion
What are 3 inhibitory effects of somatostatin?
depresses secretion of both insulin and gallbladder
decreases motility of stomach, duodenum and gallbladder
What are majority of pancreatitis cases associated with?
gallstones or alcoholism
What does pancreatitis result from?
autodigestion and inflammation of the pancreas caused by inappropriate activated pancreatic enzymes
What is diabetes mellitus?
group of disorders with relative or absolute insulin deficiency
What does diabetes mellitus result from?
inadequate supply of insulin and/or inadequate tissue response to insulin
What lab levels will be increase in pancreatits?
amylase
lipase
what does diabetes mellitus result in?
hormone induced metabolic abnormalities
microvascular and macrovascular lesions
long-term end organ complications
Describe the type 1 diabetes mellitus
autoimmune destruction of the pancreatic beta islet cells
Describe the type 2 diabetes mellitus
peripheral insulin resistance through multiple defects with insulin action and secretion
What is associated with type 1 DM?
15% associated with other autoimmune diseases (graves disease, hashimoto thyriditis, addison disease and myasthenia gravis)
How are plasma insulin levels in type 1 DM?
relatively low for the level of blood glucose (absence or minimal circulating levels)
What type of DM requires insulin therapy?
Type 1 DM
How does Type 1 DM result?
autoimmune related
results from T cell mediated destruction of beta cells within pancreatic islets
What type of DM is 90% of cases?
Type 2
What is associated with type 2 DM?
associated with excessive weight gain in adults and pediatrics
How are plasma insulin levels in type 2 DM?
plasma insulin levels are normal or increased
What is type 2 DM prone to?
susceptible to hyperglycemic-hyperosmolar nonketotic state
How does Type 2 DM result?
not immune related
results from defects in insulin receptors and postreceptor intracellular signaling pathways
What is type 1 DM susceptible to?
ketoacidosis
What are the common medications for diabetes?
acarbose biguinades dipeptidyl peptidase 4 inhibitors glucagon like peptide 1 receptor agonists meglitinide sodium-glucose transport protein 2 inhibitors sulfonylureas thiazolidinediones
What is acarbose?
delay GI glucose absorption