Pancreas and Diabetes Flashcards
What are the functions of the pancreas?
- wxocrine 2. endocrine
Describe the endocrine part of the pancreas?
produces insulin and glucagon
Where is the pancreas?
lies on posterior of the abdominal wall
What cellsproduce insulin and glucagon?
islet of Langerhans cells
Functions of insulin?
- Promotes the up-take of, storage and use of glucose 2. aids entry of amino acids into cells and the production of cellular protein
Insulin is secreted by?
beta islets cells when they detect high glucose levels
How does insulin promote glucose entry into cells?
through glucose transporters - GLUTS
How much insulin is produced in an adult?
45-50 units of insulin each day
What are the types of GLUTs?
GLUT 1-6, 8, 9, 11
GLUT1 is expressed in?
- fetal tissues 2. in adults it is expressed in erythrocytes and endothelial cells of barrier tissues such as blood-brain barrier - responsible for low-level of basal glucose uptake required to sustain respiration in cells
GLUT2 is expressed in?
- renal tubular cells 2. small intestinal epithelial cells 3. liver and pancreatic beta cells
GLUT3 is expressed in?
- neurons 2. placenta
GLUT4 is expressed in?
- adipose tissues 2. skeletal muscle 3. cardiac muscle
GLUT5 is what kind of transporter?
fructose transporter
Function of GLUT6?
transport glucose out of the endoplasmic reticulum
Describe the actions of insulin?
has anabolic effects - promotes the synthesis of larger molecules
Descibe the functions of insulin?
- increase uptake of metabolites 2. conversion of metabolites to stored forms 3. decreased breakdown of stored metabolites 4. recruitment of glucose channels to the cell membrane e.g. GLUT 4 5. use of glucose for energy over other metabolites
What is the half life of circulatory insulin?
4 hours
What breaks down insulin?
insulinases in the liver, kidney and placenta
How does insulin work in glucose uptake?
binds to IRS stimulates intracellular signaling and activates GLUT 4 which causes glucose uptake - can bind to IRS-1 or IRS-2
Describe the action of insulin in muscle cells?
- stimulates glucose uptake 2. stimulates glycogenesis (glucose - glycogen) 3. stimulates glycolysis (glucose - energy) 4. atimulates amino acid uptake and protein synthesis 5. inhibits glycogenolysis (glycogen - glucose) 6. inhibits proteolysis (protein - amino acids)
Describe the action of insulin in adipose cells?
- atimulates glucose uptake 2. stimulates lipogenesis (glucose - fatty acids) 3. inhibits lipolysis (fatty acids - energy)
Describe the action of liver cells?
- stimulates glycogenesis (glucose - glycogen) 2. inhibits glycogogenolysis (glycogen to glucose) 3. inhibits gluconeogenesis (amino acids to glucose)
Describe the action of insulin on the hypothalamus?
may stimulat satiety - fullness
Glucagon is secreted by?
alpha cells of the islets
When is glucagon released?
when blood levels of metabolites are low
Describe the actions of glucagon?
is a catabolic hormone - promotes breakdown of large molecules
Describe the functions of glucagon?
has opposite effects of insulin - 1. inhibition of glucose and amino acid uptake 2. breakdown of stored metabolites into useable metabolites 3. use of fatty acids for energy over other metabolites 4. promotes hepatic output of ketone bodies
What receptor does glucagon bind to?
G-protein-coupled receptor
What is the normal blood glucose level?
3.5 mmol/L
How is glucose homeostasis maintained?
- Insulin lowers blood glucose by stimulating uptake, metabolism and anabolism 2. Glucagon raises blood glucose by stimulating gluconeogenesis and glycogenolysis
Name the hormones that raise blood glucose levels?
- adrenaline - released in response to stress - inhibits insulin 2. cortisol - released in response to stress - reduces sensistivity to insulin 3. growth hormone - released at night - reduces sensitivity to insulin
How do these hormones raise blood glucose levels?
stimulate glycogenolysis and gluconeogenesis
What is hyperglycaemia?
excess glucose in blood - fasting concentration > 7.8 mmol/L
Hyperglycaemia is seen in?
- Diabetes mellitus: a disease caused by insulin deficiency or insulin resistance 2. Glucagonoma: a rare tumour of the alpha cells that secrete glucagon
What is hypoglycaemia?
a deficiency of blood glucose - a concentration < 2.5 mmol/L
What is hypoglycaemia caused by?
- Overtreatment of diabetes mellitus, either excess insulin or beta cell stimulating drug 2. Non-diabetic disorder causing fasting Hypoglycaemia 3. Idiopathic excessive insulin secretion causing Hypoglycaemia after glucose ingestion 4. Insulinoma, with hypersecretion of insulin
What is diabetes mellitus?
caused by insulin deficiency or insensitivity - leads to hyperglycaemia
Describe the 2 types of diabetes?
- Type1 or insulin dependent DM(IDDM): caused by insulin deficiency 2. Type 2 or non insulin-dependent DM (NIDDM): caused by insulin deficiency and/or resistance
Describe type 1 diabetes?
- Caused by autoimmune destruction of the beta cells and insulin deficiency 2. Common in the young but can occur at any age 3. There is a genetic component of about 30%
Describe type 2 diabetes?
- A disease of the elderly especially obese people 2. Accounts for 90% of diabetes cases worldwide 3. Caused by insulin deficiency, insulin resistance or a combination of both
What is the diagnosis of diabetes?
Blood glucose levels are normally 3.5 – 5.5 mmol/L after an overnight fast so DM is diagnosed if fasting glucose is above 7.8 mmol/L on two occasions
What are the markers that suggest close observation in diagnosing diabetes?
- glycosuria - glucose in urine 2. Fasting blood glucose of 6 – 7 mmol/L 3. Random blood glucose of >11.1 mmol/L
Describe the treatment of diabetes?
- diet alone (type 2) 2. diet and oral hypoglycaemic agents (type 2) 3. diet and insulin (types 1 and 2) - All patients with Type 1 and many with Type 2 are treated with subcutaneous insulin injections to reduce acute and chronic complications
What else is managed alongside diabetes?
obesity, hypertension and dyslipidaemia
What diet should a person with diabetes observe?
- Avoid carbohydrates that can be rapidly absorbed (e.g. glucose) to prevent hyperglycaemia 2. Eat regular, small meals to prevent hypoglycaemia 3. Control calorie intake to lose/stabilize weight (especially Type 2) 4. Eat low-fat, healthy diet to reduce atherosclerosis
What are oral hypoglycaemic agents for Type 2 Diabetes?
oral medication to lower blood glucose
Why are subcutaneous insulin injections taken?
insulin gets inactivated by digestion if taken orally
What do insulin injections treat?
all Type 1 patients and some Type 2 patients
Why is rembinant human insulin preffered over porcine insuline?
it reduces immunological reactions
Describe the administration of insulin injections?
- Long acting insulin is given in the morning and at night 2. Short acting insulin is given 15 min prior to a meal
