Diabetes And Endocrine Regulation Of Glucose Metabolism

Front 1

What is insulin released by?

Back 1

Beta cells of the islets of langerhans in the pancreas.

Front 2

What is the effect of insulin secretion?

Back 2

Stimulated peripheral glucose uptake.

Front 3

Where is glucagon released from?

Back 3

Alpha cells of the pancreatic islets of langerhans.

Front 4

What is the effect of glucagon on the body?

Back 4

Antagonises insulin action and increases gluconeogenesis.

Front 5

Describe the physiological processes which occur following a meal.

Back 5

After a meal blood glucose levels are high

1. This stimulates the secretion of insulin into the blood

2. Cells are stimulated to uptake glucose

3. Blood glucose falls

4. Insulin secretion decreases

Front 6

Describe the physiological processes which occur when exercising or during a fasting period.

Back 6

During a fasting period / during exercise blood glucose levels are low

1. This stimulates glucagon secretion

2. glucagon causes cells to release glucose - via gluconeogenesis + glycogenolysis

3. Blood sugar levels of glucose rise

4. Glucose secretion decreases

Front 7

Biochemically, how does insulin increase glucose uptake into cells?

Back 7

Insulin promotes transmembrane transport by binding GLUT4 transporters onto cell membranes.

Front 8

Describe the mechanism by which insulin attaches GLUT4 glucose transporters to cell membranes.

Back 8

1. Insulin binds to the Insulin Receptor - a tyrosine kinase receptor which autophosphorylates.

2. This activates a signalling pathway via IRS-1

3. IRS1 goes on to activate Pl3 - Kinase, in turn activating PDK (transports PIP3) and finally Akt (which also activates glyogen synthase)

4. The activated signalling pathway causes the translocation of the intracellular GLUT4 transporter to the cell surface

5. GLUT4 binds to the cell surface importing glucose across the membrane into the cell

Front 9

What is the difference between the types of diabetes mellitus?

Back 9

1. Primary Diabetes mellitus - Insulin resistance

i) Type I - genetic

ii) Type II - accrued over time

2. Secondary Diabetes mellitus - Islet of Langerhans pathology

i) Congenital rubella

ii) Pancreatitis

iii) Drugs - corticosteroids

Front 10

What is the cause of primary type I diabetes?

Back 10

Antibodies attack beta cells of the islets of langerhans (90% reduction)

Front 11

What is microangiopathy?

Back 11

A disease which affects the small blood vessels in the body.

Front 12

What causes microangiopathy?

Back 12

Glycosylation of vital proteins - Type IV collagen

Overglycosylation of type IV collagen results in its excess deposition into the basement membrane.

Front 13

What is the result of microangiopathy on the function of the blood vessels?

Back 13

1. Thick + leaky blood vessels

2. Organ damage

3. Choroid Ischemia and protein loss into tissues

Front 14

How is microangiopathy diagnosed?

Back 14

Diagnosed by:

1. Urine tests

2. Blood glucose tests

Front 15

What is the aim of the HbA1C test?

Back 15

Aims to measure the long term average of blood glucose levels.

Front 16

Insulin can now be taken as a drug. How has insulin drug efficiency been honed since the leaps in genetic technology?

Back 16

Recombinant DNA technology allows creation of differing insulin efficiencies by the creation of modified insulin analogs.

Front 17

What insulin properties be modified?

Back 17

1. Activity of the insulin

2. Length of action of insulin

Front 18

What types of drugs can be used to treat type II diabetes?

Back 18

1. Sulfonylureas - stimulate beta cells

2. Biguanies - improves cells ability to intake glucose

3. Thiazlidinediones

4. Alpha glycosidase inhibitors - block starch digesting enzymes

5. Meglitinides - stimulates beta cells

Front 19

What is the mechanism of action of sulphonylureas?

Back 19

1. Interacts with beta cell receptors to block ATP sensitive K+ channels

2. Blocking of K+ channels causes the opening of Ca++ channels

3. Insulin released

Front 20

What is the mechanism of biguanides?

Back 20

1. Inhibits glucose production in liver and increases amount of GLUT4 moved to the cell membranes

Front 21

What is the mechanism of action of thiazolidines?

Back 21

1. Binds to and activates the gamma isoform of the peroxisome proliferator activated receptor -

2. The resultant complex controls many glucose / FA metabolism genes

Front 22

What is the mechanism of action of alpha glycosidase inhibitors?

Back 22

Block action of enzymes which help to digest starches

Front 23

What surgical treatments exist for diabetes?

Back 23

1. Pancreas transplant

2. Islet cell transplants

3. Stem cells