Insulin Secretion and Signalling

Question 1

What type of cells are in found i the pancreas

Answer 1

Alpha
Beta
S cells
PP cells

Question 2

What do the beta cells do

Answer 2

Secrete insulin

Question 3

What do alpha cells do

Answer 3

Secrete glucagon

Question 4

What do the S cells do

Answer 4

Secrete somatostatin

Question 5

What do the PP cells do

Answer 5

Secrete pancreatic polypeptide

Question 6

Where and how is the insulin peptide structure synthesised

Answer 6

Int he RER of pancreatic beta cells as a larger single chain preprohormone - preproinsulin

Question 7

Insulin peptide structure is cleaved to form what

Answer 7

Insulin

Question 8

What does the insulin peptide structure contain

Answer 8

2 polypeptide chains linked by disulphide bonds

Question 9

What type of product is the c peptide

Answer 9

A waste product with no known physiological function

Question 10

Describe the variation in insulin amino acid sequence from species to species

Answer 10

Very little variation

Question 11

What is used to avoid the problem of antibody formation

Answer 11

Human insulin instead of other animal insulin

Question 12

How does Glucose enter the beta cells

Answer 12

Throughout he GLUT2 glucose transporter

Question 13

What happens to the glucose when it enters the cell

Answer 13

it is phosphorylated by glucokinase

Question 14

What cells sense the glucose levels in the blood

Answer 14

beta cells

Question 15

Describe the relationship between the intracellular concentration to the extracellular concentration of glucose

Answer 15

Directly proportional

Question 16

What will phosphorylate glucose at low concentrations

Answer 16

Hexokinase

Question 17

What does a change of glucose concentration lead to

Answer 17

A dramatic change in glucokinase activity

Question 18

An increased metabolism of glucose leads to what

Answer 18

An increase in intracellular ATP concentration

Question 19

How many ATP molecules are produced per glucose molecule

Answer 19

36

Question 20

What does ATP inhibit

Answer 20

The ATP sensitive K+ channel (KATP)

Question 21

If the KATP is inhibited, what does this do to the levels of K+ in the cells

Answer 21

It increases it and causes depolarisaiton which will then result in the opening of the voltage gated claim channels.

Question 22

If calcium is coming into the cell, what will be allowed

Answer 22

A release of insulin into the blood.

Question 23

Inhibition of what leads to depolarisation of the cell membrane

Answer 23

Inhibition of KATP

Question 24

What results in the opening of voltage-gated Ca2+ channels

Answer 24

Depolarisaiton of the cell membrane

Question 25

What does an increase in internal Ca2+ concentration lead to

Answer 25

fusion of secretory vesicles within the cell membrane and release of insulin

Question 26

what is the term used to describe the release of insulin

Answer 26

Biphasic

Question 27

What is the RRP

Answer 27

Readily releasable pool of insulin

Question 28

How much insulin granules are immediately available for release

Answer 28

5%

Question 29

What 2 proteins do KATP channels consist of

Answer 29

Kir6.1 (inward rectifier subunit | SUR1 (a sulphonylurea receptor)

Question 30

What are both Kir6.1 and SUR1 required for

Answer 30

To form a functional channel

Question 31

How does intracellular ATP elicit depolarisation

Answer 31

By inhibiting KATP

Question 32

KATP is directly inhibited by what class of drug

Answer 32

Sulphonylurea e.g tolbutamide or glibenclamide

Question 33

KATP is stimulated by what? What does this do to insulin secretion

Answer 33

Diazoxide - it inhibits insulin secretion

Question 34

If a patient has an overactive KATP channel, what are they most likely to have

Answer 34

Profound neonatal diabetes

Question 35

If a patient has an inactive KATP channel, what are they most likely to be

Answer 35

Hyperinsulinaemic

Question 36

What does MODY stand for

Answer 36

Mature onset Diabetes of the Young

Question 37

What causes MODY

Answer 37

Mutations in at least 6 different genes

Question 38

What play key roles in pancreas foetus development and neogenesis

Answer 38

HNF transcription factors

Question 39

What else do HNF transcription factors do

Answer 39

Regulate beta cell differentiation and function

Question 40

what is the main difference in treatment between MODY and type 1

Answer 40

Type 1 is treated with insulin | MODY is treated with sulphonylurea

Question 41

What is the main problem in MODY

Answer 41

defective gluose sensing in the pancreas and/or loss of insulin secretion

Question 42

What is the main problem in Type 1 diabetes

Answer 42

Loss of insulin secreting beta cells

Question 43

What is the main problem in type 2 diabetes

Answer 43

Initially hyperglycemia with hyperinsulinaemia so primary problem is reduced insulin sensitivity in tissues

Question 44

What is one of the major functions that regulates protein function in the cell

Answer 44

Protein phosphyorylation | this provides a reversible method for altering protein function

Question 45

Where can proteins get phosphorylated

Answer 45

On any hydroxyl group

Question 46

Insulin receptor is a what

Answer 46

Dimeric tyrosine kinase

Question 47

Binding of insulin to the alpha subunits causes what

Answer 47

Beta subunits to phosphorylate themselves, thus activating the catalytic activity of the receptor

Question 48

What is done through eh GLUT 4 pathway

Answer 48

Glucose transport into muscle and into fat

Question 49

In what patients does the GLUT4 pathway not occur

Answer 49

Those with diabetes

Question 50

What 7 different things does insulin effect

Answer 50

``` Amino acid uptake in muscle DNA synthesis Protein synthesis Growth responses Glucose uptake in muscle and adipose tissue Lipogenesis in adipose tissue and liver Glycogen synthesis in liver and muscle ```

Question 51

Where are ketone bodies formed

Answer 51

In liver mitochondria

Question 52

What are ketone bodies derived from

Answer 52

Acetyl-coA from beta oxidation

Question 53

Why are ketone bodies important physiologically

Answer 53

They are molecules of energy metabolism for heart muscle and renal cortex

Question 54

What are oxidised when glucose is not available

Answer 54

Fatty acids

Question 55

What is converted to ketone bodies

Answer 55

Excess acetyl co-A

Question 56

What can lead to acidosis

Answer 56

Accumulation of ketone bodies

Question 57

What does a high glucose excretion cause

Answer 57

Dehydration and exacerbates acidosis

Question 58

What can ketosis result in

Answer 58

Coma or death

Question 59

What type of diabetes is ketoacidosis most associated with

Answer 59

type 1