Diabetes Flashcards
what does ‘diabetes’ mean?
the excessive urination and a persistent thirst
in greek it means ‘a siphon’ because people passed water like a siphon’
where does the mellitus of diabetes mellitus come form?
tasted the pee and it was sweet
mellitus = honey
Thomas Willis, who rediscovered the connection between diabetes and sweetness by conducting his taste test. He renamed the disease diabetes mellitus; mellitus is Greek for “like honey.”
what are the two common types of diabetes?
- Diabetes mellitus (of or pertaining to honey – sweet tasting) - a disease in which insulin has insuffient function leading to unregulated blood glucose levels
- Diabetes insipidus (lacking flavour) – a disease in which the pituitary gland does not secrete sufficient vasopressin (large amounts of urine still)
what are the three main classifications of diabetes mellitus (DM)?
- Type 1 – “absolute insulin deficiency” - Body attacks cells that make insulin (pancreatic beta cells) if these cells die out can no longer make insuin
- Type 2 – “insulin resistance” Body becomes resistant to insulin effects
- Gestational - is a condition in which women without previously diagnosed diabetes exhibit high blood glucose levels during pregnancy (esp. during the third trimester due to changes in renal absorption of glucose).
describe the relationship between blood sugar regulation and (bacterial) infection ?
Disease states can alter the normal balance of blood glucose
As part of the body’s defence mechanism for fighting illness and infection, more glucose is released into the blood stream.
Bacterial really like to grow on glucose - if there is lots in your blood stream then the bacterial have more food
High blood sugar unleashes destructive molecules that interfere with the body’s natural infection-control defenses.
two dicarbonyls — methylglyoxal (MGO) and glyoxal (GO) — alter the structure of human beta-defensin-2 (hBD-2) peptides, crippling their ability to fight inflammation and infection.
what two hormones work together to maintain an appropriate blood glucose level?
insulin and glucagon
breifly describe how your blood glucose levels change throughout the day
after breakfast there is a spike of glucose and then after a little while there is a small increase again (as the body have broken donw the starches)
this same thing happens at lunch and dinner
after dinner levels continue to decrease throughout the night until breakfast
describe the similarity between blood glucose and insulin levels in the body
The insulin levels mirror the blood sugar levels
they go up when the sugar goes up
why do the blood glucose levels never fo donw to zero?
because cells always need an energy source
what ways can glucose be stored?
as glycogen or fats
describe the function of insulin
When glucose levels increase, pancreatic beta cells are sitmulated to release insulin
This causes the
Body cells take up more glucose and Liver to take up glucose and stores it as glycogen
Causing blood glucose levels to fall
describe the function of glucagon
when glucose levels get low, pancreatic alpha cells are stimulated to release glucagon
this stimulates the liver to break down glycogen and release glucose to the blood
causing blood glucose levels to rise
what is the exocrine function of the pancreas?
The exocrine pancreas is responsible for secretion of digestive enzymes, ions and water into the duodenum of the gastrointestinal tract.
The digestive enzymes are essential for processing foodstuffs in meals to molecular constituents that can be absorbed across the gastrointestinal surface epithelium.
Acini cells are responsible for producing and secreting these enzymes into the pancreatic duct
End of pancreatic duct is the acini cells with duct in middle, along with lots of capillaries
what is diabetic ketoacidosis?
- a serious complication of diabetes that can be life-threatening.
- DKA develops when your body doesn’t have enough insulin to allow blood sugar into your cells for use as energy. Without enough insulin, the body begins to break down fat as fuel. This causes a buildup of acids in the bloodstream called ketones. If it’s left untreated, the buildup can lead to DKA
- ## DKA is most common among people with type 1 diabetes. People with type 2 diabetes can also develop DKA.
what is the endocrine function of the pancreas?
The endocrine component of the pancreas consists of islet cells (islets of Langerhans) that create and release important hormones directly into the bloodstream (plasma).
Two of the main pancreatic hormones are insulin (release by beta cells), which acts to lower blood sugar, and glucagon (release by alpha cells), which acts to raise blood sugar.
what are the four major cells of the Islets of Langerhans?
Pancreatic Beta-cells comprise the majority of pancreatic islet cell population; secrete insulin.
Pancreatic Alpha-cells cells in the islet of Langerhans which secrete glucagon.
Pancreatic PP-cells PP cells secrete pancreatic polypeptide.
Pancreatic Delta-cells cells in the islet of Langerhans; known to secrete somatostatin, and vasoactive intestinal peptide.
describe the cellular role of insulin
what four things does it result in
In its monomeric form, insulin will bind to its insulin receptor causing a conformational change
This results in:
- an increase in glucose gransporters (GLUT4)
- glucose conversion to glycogen
- glucose conversion to fatty acids
- glucose channelling into metabolism/conversion to pyruvate
how is insulin made?
the insulin gene is transcribed and translated into preproinsulin
the signal recognition particle recognises the signal sequence and brings it to a translocon where its inserted into the ER membrane
then the rest of the protein can be made as its forced through the translocon into the ER lumen where it is folded
then the signal sequence is cleaved off (by signal peptidase)
now left with a soluble protein (proinsulin)
this goes through the Golgi where the C peptide is cleaved off by prohormone convertases, PC2 and PC1/3 and Carboxypeptidase to produce mature insulin
final packaging into secretory granules as a zinc bound hexamer (storage form)
from the ER lumen through the golgi to secretory vesicles the pH drops considerably so the protein precipitates
what is the pI?
isoelectric point
isoelectric point is the overall charge of the protein
(sum of positive and negative side chains of amino acids)
what happens if the pI of the protein is close to that of the buffer?
the protein precipitates
what is the isoelectric point of insulin?
pi of insulin ~ 5.4
what are the pH values of the Er lumen, the golgi and secretory vesicles?
ER lumen - pH7.2
Golgi - pH 6.7 -> 6.0
Secretory vesicles - pH5.7
why is it important that the isoelectric point of insulin is close to that of the secretory vesicles?
if pi is close to that of the buffer then it precipitates
precipitation slows down the release of insulin
meaning its in its storage form in the secretory vesicles
what is Znt8?
a zinc transporter that channels zinc ions into secretory vesicles for binding with insulin to generate its stored form
it is a genetic risk factor for the development of both type 1 and 2 diabetes