WEEK 3 Flashcards
Where is the pancreas located?
beneath liver and tucked into curvature of duodenum
What are the exocrine functions of the pancreas?
- secretes enzymes into duodenum to support digestion of macromolecules
- secretes bicarbonate into duodenum to raise pH of chyme
What are endocrine functions of pancreas
- islet of langerhans include two types of cells that secrete hormones
. alpha cells - secrete glucagon in response to low blood glucose and to activity of sympathetic nervous system
. Beta cells - secrete insulin in response to high blood glucose and to activate of parasympathetic nervous system
what are the islet of langerhans
groups of pancreatic cells secreting insulin and glucagon
what does glucagon do?
raises blood glucose
what does insulin do
lowers blood glucose
Why is glucose important?
it is a preferred source of energy to produce ATP by cells of body
normal range for BG
during fasting - 4-7mmol/L
2 hours after meals - 5-10mmol/L (5-8) if tightly controlled
Why is insulin called a hypoglycemic hormone?
acts to decrease BG levels
difference between glucose and glycogen
glucose - found in blood
glycogen - found in liver and muscle cells and is a collection of many glucose molecules that is stored for future use (like a camel)
How does insulin bring the blood sugar down?
- decreased glycogenolysis - inhibits breakdown of glycogen to glucose
- decreased gluconeogenesis - inhibits making of glucose from non-carbs
- increased glycogenesis - turns glucose into glycogen
How does glucagon increase blood glucose
-increase glycogenolysis - breaks down glycogen to glucose
- increase gluconeogenesis - turns non-carbs into glucose
Why is glucagon a hyperglycemic hormone
Acts to increase BG levels
think of proinsulin as insulin’s dad
How is insulin made?
- Proinsulin is composed of an A peptie chain and a B peptide chain connected by a C peptide chain and 2 disulfide bonds
- C peptide is cleaed by proteolytic enzymes, leaving the bonded A and B peptide chains that become insulin
What is C peptide a measure for in the blood?
indirect measure of serum insulin synthesis
Glucose uptake: How does insulin work?
- Insulin binds with plamsa membrane receptors in cell found throughout the body
- as insulin binds, it sets off a cascade of signals to activate glucose transporters (GLUT) for entry of glucose into cell
Where is GLUT stored?
- stored in cellular vesicles until activated by insulin recpetors
- it is then translocated to cell surface where it facilitates the diffusion of glucose into the cell
- translocation of GLUT4 to cell surface is associated with a 10-21 fold increase in glucose fiddusion into the cell - skletal, cardiac, liver, adipose cells
Fast acting vs slow acting hyperglycemic hormones (AKA counter regulatory/ stress hormones)
FGE (Fast England Girl), SGGC - (Slow Gnome Growth Candy)
fast acting - EG - glucagon and epinephrine
Slow acting - GGC - growth hormone, glucocorticoid hormones, cortisol
effect of counter regulatory hormones - infection, illness, injury, surgery, physical/emotional stress
- causes hyperglycemia
- increases epinephrine, increased GH, increases cortisol and inhibits glucose uptake into cells - increase in BG through glucogenolysis and glycogenolysis- inhibits insulin release
- causes increase in BG and hyperglycemia and ketoacidisos can occur
when ill - effect of counter regulatory hormone
- drug regime may change when client is having surgery or some diagnostic test
- ct. must understand that drugs for diabetes should not be withheld during times of illness because counter regulatory mechanisms often increase BG
- food intake is also important during this time because body requires extra energy
- extra insulin may be necessary to meet demands placed on body and to prevent onset of DKA in ctwith type 1 diabetes
What is diabetes?
- affects metabolism of carbs, fat and protein
- characterized by hyperglycemia - resulting from defects in - insulin secretion, insulin action, or both
- categories - type 1, type 2, gestational diabetes, other specific types
Type 1 diabetes: common theory (how it happens)
Autoimmune - genetic and environmental factors, resulting in gradual process of autoimmune destruction in genetically susceptible individuals
Nonautoimmune: Unknown
Type 1 diabetes: presence of antibody
Autoantibodies to insulin and glutamic acid decarboxylase (GAD65)