w4 diabetes type 1 PAT202 Flashcards
what is diabetes?
a disease caused by genetic and environmental factors that impairs the cellular use of glucose
alpha cells secrets_?
glucagon-in response to low blood glucose to activiate the sympathetic nervous system
(secreted by pancreas-endocrine function)
beta cells secrete_
insulin in response to high blood glucose and to activity of parasympathetic nervous system
(secreted by pancreas-endocrine function)
what is glucagon?
pancreatic hormone that acts to increase blood glucose levels- it is secreted when BG is low
- and maintains stable blood glucose levels between meals and during periods of fasting
- it removes glucose from its storage in the liver and send it to the blood (glycogenolysis) raising serum glucose w/in minutes
- increase glycogenolysis- breaks down glycogen to glucose
- increase glyconeogenesis- turns non carbs (fats & proteins) into glucose
what is insulin?
pancreatic hormone that acts to decrease blood glucose levels
-has a hypoglycaemic effect b/c its presence causes glucose to leave the blood and serum glucose to fall
w/out insulin glucose is not able to enter cells of the body. these cells may be surrounded by high amounts of glucose but they are unable to use it until insulin arrives
-secretions are increased during fed state
glucose transport: ↑uptake by GLUT-4 receptors into skeletal muscle & adipose tissue
-↓glycogenolysis: inhibits breakdown of glycogen to glucose
↓gluconeogenesis: inhibits making of glucose from non-carbs
↑glycogenesis: turns glucose into glycogen (promotes glycogen storage)
what happens when levels of glucose are low?
glucagon is secreted, and its primary function is to maintain adequate blood glucose levels between meals
-glucagon has a hyperglycemic effect b/c it causes blood glucose to rise
what are the hormones associated w/ hyperglycaemia
- epinephrine
- thyroid hormones
- growth hormone
- corticosteroids
what is the normal range of serum glucose during fasting?
4-7 mmol/L
what is the normal glucose range after meals
5-10mmol/L (or 5-8 if tightly controlled)
what happens after a meal?
glucose is rapidly absorbed from the GI tract, and serum levels rise
-some of the glucose is taken up by the cells and used for immediate energy needs, but above two-thirds is stored in the liver and muscle cells as glycogen, the storage form of glucose
what is glycogenolysis?
when glucose levels fall between meals, glycogen is broken down in a process called glycogenolysis-(the process of glycogen breaking down) and glucose is released into the blood stream
insulin is secreted by which organ?
pancreas - it will recognize the rising serum glucose levels and release insulin
what are the physiological actions of insulin?
- promotes the entry of glucose into cells
- provides for the storage of glucose, as glycogen
- inhibits the breakdown of fats and glycogen
- increases protein synthesis and inhibits gluconegenesis- which is the production of new glucose from non-carhohydrate molecules
a hypoglycaemic state (low serum glucose stimulates the release of _
glucagon and inhibits the release of insulin
a hyperglycemic state (high serum glucose) stimulates_
the release of insulin and inhibits the release of glucagon
what are factors that decrease blood glucose levels?
fasting
exercise
alchohol
what are factors that increase blood glucose levels
stress from infection
- injury
- surgery =triggers release of epinephrine and nonrepinephrine
- large meals/over consumption of carbohydrates
- growth hormone
- corticosteroids
what is type 1 DM?
results from autoimmune destruction of pancreatic beta cells, causing an absolute lack of insulin secretions
-thought to be caused by an interaction of genetic, immunological, and environmental factors
what are the S/S of type 1 DM?
- hyperglycemia (most diagnostic sign)
- polyuria- excessive urination
- polyphagia- increased hunger
- polydipsia-increased thirst
- glucosuria-high levels of glucose in the urine
- weight loss
- fatigue
- bedwetting in children who previously didn’t wet the bed during the night
- irritability and other mood changed
- blurred vision
what happens if DM goes untreated?
produces long-term damage to arteries, which leads to heart disease, stroke, kidney disease, and blindness
- lack of adequate circulation to the feet may cause gangrene of the toes, which may require amputation
- nerve degeneration is common and produces symptoms ranging from tingling in the fingers/toes to a complete loss of sensation of a limb
if glucose is unable to enter the cell, how does the body get energy?
-uses lipids as energy source and keto acids- (a acidic waste product of lipid metabolism that lowers the pH of the blood) causing diabetic ketoacidosis (DKA)
what is diabetic ketoacidosis? DKA
type of metabolic acidosis d/t an excess of ketone bodies-can progress to coma and death if untreated
what is type 2 diabetes?
chronic metabolic disease caused by insufficient secretions of insulin by the pancreas and a lack of sensitivity of insulin receptors
what is the function of pancreas (the exocrine function)
- secretes enzymes into duodenum to support digestion of macromolecules
- secretes bicarbonate into duodenum to raise pH of chyme
what is the function of the pancreas- endocrine function
islets of Langerhans includes two types of cells that secrete hormones
alpha and beta cells
how does insulin work?
Insulin binds with plasma membrane receptors found on cells throughout the body
-receptor binding sends cascade of signals to activate glucose transporters (GLUT) for entry of glucose into the cell
The primary GLUT is called GLUT4
-stored in cellular vesicles until activated by the insulin receptor
-is then translocated to cell surface where it facilitates the diffusion of glucose into the cell
Translocation of GLUT4 to the cell surface is associated with a 10- to 21-fold increase in glucose diffusion into the cell
-skeletal, cardiac muscle, liver, adipose cells
what is a glucose transporters? (GLUT)
insulin promotes formation of glucose transports (GLUT4) that bring glucose from blood into the cells
why is infection, illness, injury/trauma, surgery, physical, and emotional stress an issue w/ DM?
causes hyperglycaemia (counter regulatory hormone response)
- increase of epinephrine, growth hormone and cortisol
- inhibits glucose uptake into cells and increase blood glucose through glycogenolysis and gluconeogenesis: inhibits insulin release
- causes increase blood glucose =hyperglycaemia and ketoacidosis can occur
genetic susceptibility for type 1 DM
- first degree relative (parent or sibling) w/ type 1 diabetes
- strongest association w/ major histocompatibility complex (MHC)
environmental factors of type 1 DM?
- viral infection
- helicobacter pylori
- exposures to cow’s milk proteins
- relative lack of vitamin D (also implicated)
what is the goal of treatment for type 1 DM?
- restoration of near normal BG levels and correct of repeated metabolic disorders
- treatment include: insulin, meal planning, exercise, and self-monitoring of BG
- transplant -islet cells and the whole pancreas
