ENDO-pancreas and diabetes Flashcards
where are GLUT 1 receptors located?
- Brain
- erythrocyte
- placenta
- fetal tissue
where are GLUT 2 receptors located?
- Liver
- kidney
- intestine
- pancreas beta cells
where are GLUT 3 receptors located?
brain
where are GLUT 4 receptors located?
- muscle
- adipose tissue
where are GLUT 5 receptors located?
jejunum-(middle part of s.intestine between duodenum and ileum)
where are Sodium dependent glucose transporters (SDGLTs) located?
- Small intestine
- proximal tubule of nephron
why is a continuous and steady supply of glucose needed?
essential for brain function & important for many other tissues
what is the specific limit for glucose?
fasting- 4.0-5.4 mmol/L
fed (at least 90 mins after meal)- under 7.8 mmol/L
how does glucose enter cells?
via glucose transporters->using a facilitated diffusion mechanism
What does it mean when GLUT transporters have low k.m?
transport a lot of glucose ->need less glucose for the transporters to work
what is the role of insulin in uptake of glucose?
Insulin accelerates the uptake of blood glucose into the liver by GLUT 2
(not necessary but accelerates)
outline the mechanism of GLUT 2
- The glucokinase sites become occupied with glucose = converting glucose -> glucose 6-phosphate
- increase in glucose 6-phosphate & insulin action leads to a build-up of glycogen stores in the liver.
- glucose released when blood glucose low
outline the mechanism of GLUT 4
- Insulin binds to tyrosine kinase receptor
- Triggers protein kinase cascade
- Glut 4 transporters travel to cell surface membrane by exocytosis
- Glucose enters the cell
what is glucose converted to in adipose tissue?
fatty acids
what is glucose converted to in skeletal muscle tissue?
glycogen
what do SDGLTs contribute to?
renal glucose absorption in the small intestine and PCT
Is the pancreas retroperitoneal or intraperitoneal?
Retroperitoneal except for the tail which is intraperitoneal
what % of pancreas function is endocrine?
10%
what % of pancreas function is exocrine?
90%
what are the islets of langerhans?
regions of pancreas that have endocrine cells (10% endocrine function of pancreas-> bloodstream)
which cells are in the islet of langerhans?
- alpha
- beta
- delta
- pancreatic polypeptide cells
what do alpha cells secrete?
glucagon
what is the main target organ of alpha cells secretions?
liver
what is glucagon inhibited by?
somatostatin & insulin
what is glucagon stimulated by?
- low blood glucose in fasting state
- sympathetic NS
- rise in blood amino acids
what is the function of glucagon?
- increase blood glucose levels
- stimulate glycogenolysis & gluconeogenesis
- inhibit glycogenesis
- increases lipolysis
what do delta cells secrete?
somatostatin
what does stomatostatin do?
inhibits the secretion of insulin & glucagon
what is the role of pancreatic polypeptide cells?
inhibits the secretion of somatostatin
what do beta cells secrete?
insulin
what inhibits insulin secretion?
somatostatin
what are the functions of insulin?
- lowers blood glucose level
- Increases uptake and storage of glucose, fatty acids and amino acids mainly in the liver and muscle tissue (glycogenesis, lipogenesis, and protein synthesis).
what is insulin release stimulated by?
- high glucose in fed state
- parasympathetic NS
- gastric inhibitory peptide (GIP)
- glucagon like peptide 1 (GLP1)
how does insulin act on the liver?
- suppresses of gluconeogenesis
- acceleration of glycogenesis and fatty acid synthesis
how does insulin act on the muscles?
- promotes the uptake of amino acids
- stimulates protein synthesis
how do beta cells work?
- > Glucose enters the cell via GLUT-2
- > Glucose–>Glucose-6-phosphate (G6P) via glucokinase
- > G6P stimulates glycolysis to produce ATP
- > ATP sensitive potassium channels close
- > Potassium build up in the cell opens the voltage gated calcium channels (normally closed)
- > The increased calcium induces the secretion of insulin
What are incretins?
->Gut hormones secreted by enteroendocrine cells into the blood after eating-regulate the amount of insulin that is secreted
what is hyperglycaemia?
too much glucose in the blood -> can cause major damage!!
what is ketoacidosis?
- lack of insulin = glucose can’t be processed -> another form of energy: fat breakdown.
- > This forms ketones =build up in body-toxic
what are the symptoms of type 1 diabetes?
- > Thirst
- > Large volume of dilute urine (polyuria)
- > Weight loss
- > fatigue
what is type 1 diabetes caused by?
autoimmune destruction of beta cells
what does type 1 diabetes result in?
- > Results in little/no insulin production = can’t decrease glucose levels
- > Uncontrolled gluconeogenesis
- > failure of glucose uptake in muscle & fat
- > use of alternative fuels
- > Hyperglycemia
- > ketoacidosis
- > coma & death
when is type 1 diabetes most commonly diagnosed?
childhood
what is a major risk factor of type 1 diabetes?
genetics
what is type 2 diabetes caused by?
resistance to insulin
how do beta cells try and overcome the resistance to insulin? what does this result in?
- excess insulin produced by beta cells to compensate & control blood glucose levels
- overtime beta cell function declines = high glucose levels (hyperglycemia)
what are the symptoms of type 2 diabetes?
- > Thirst
- > Large volumes of dilute urine produced
- > Weight loss
- > fatigue
when is type 2 diabetes most commonly diagnosed?
40s can occur from 25
what is a major factor of type 2 diabetes?
obesity
Which of the following cell types is NOT found in the pancreas?
a. acinar cells
b. alpha cells
c. beta cells
d. kappa cells
e. delta cells
d-kappa
acinar cells-make and secrete digestive enzymes
Which hormone is responsible for uptake of glucose from blood by cells?
a. insulin
b. renin
c. angiotensin
d. leptin
e. melatonin
a-insulin
insulin a. Produced by the pancreas B. Causes glycogen formation C. Allows cells within insulin receptors to take up glucose to decrease blood sugar D. A and C E. All the above
E
