Insulin (Hormone Action 2)

Question 1

Insulin Classification

Answer 1

Peptide hormone (51 a.a.), hydrophilic, binds to cell surface, tyrosine kinase receptor (signal transduction via phosphorylation)

Question 2

Insulin Natural Outline

Answer 2

Produced in pancreas. Allows glucose entry from blood to tissue (eg muscle and adipose). Nourishes cell and removes glucose from blood

Question 3

Type 1 Diabetes

Answer 3

Inability to synthesize insulin due to loss of beta cells. Hyperglycemia

Question 4

Type 2 Diabetes

Answer 4

Impairment/ Inability to respond to insulin and dysregulation of beta cells. Poor glycemic control

Question 5

5 endocrine cells of isles of langerhans

Answer 5

Acinar, Pancreatic acini, Alpha, Beta and Delta

Question 6

Alpha Cell Outline

Answer 6

Produces glucagon. Stimulates beta cells release of insulin. Inhibited by somatostatin and insulin (at certain level)

Question 7

Beta Cell Outline

Answer 7

Produces insulin. Acts on Delta cells to regulate stomatison release. Stimulated by glucagon, inhibited by somatostatin

Question 8

Delta Cell Outline

Answer 8

Produces somatosatin. Acts as regulatory feedback mechanism. Inhibits glucagon and insulin

Question 9

Insulin Synthesis Stages

Answer 9

Pre-proinsulin, proinsulin, maturation and insulin finalisation

Question 10

Pre-proinsulin Def.

Answer 10

IN endoplasmic recticulum. Produced as a single polypeptide

Question 11

Proinsulin

Answer 11

Single peptide is removed from pre-postinsulin peptide chain

Question 12

Maturation

Answer 12

Golgi Apparatus, proinsulin folds to form disulfide bonds and packaged into secretory granules

Question 13

Insulin Finalisation

Answer 13

In granules proinsulin is divided into insulin and C-peptide

Question 14

Insulin Secretion

Answer 14

High blood glucose conc. triggers granules fuse with membrane and excrete (exocytosis) insulin and c-peptides into blood (in equal amopunts)

Question 15

GLUT2 Definition

Answer 15

Transfer protein for glucose through membrane

Question 16

How Glucose crosses membrane

Answer 16

Increase in glycolysis in respiration, increases ATP. ATP sensitive K+ channels close and voltage gated Ca^2+ open (depolarisation). Causes vesticles fuse to membrane

Question 17

Insulin Receptor Compoaition

Answer 17

2 Subuints (alpha and beta) linked by disulfide bonds. Alpha is extracellular (insulin binds to it) and beta penetrates membrane (phosphorylates activating catalytic site)

Question 18

Insulin Receptor Type

Answer 18

Tyrosine Kinase

Question 19

Signal Propagation By Phosphorylation

Answer 19

Receptor Substrate-1 is stimulated by phosphorylated. This propagates signals

Question 20

Rapid Insulin Effects

Answer 20

Glucose uptake, amino acid and K+ iontransport

Question 21

Intermediate Insulin Effect

Answer 21

Protein synthesis stimulation, glycosis and glycogenesis, inhibition of glycogenlysis + gluconeogenesis and inhibition of proteolysis

Question 22

Delayed Insulin Effects

Answer 22

Transcription of Lipogenic Genes

Question 23

Factors Regulating Insulin Release

Answer 23

Blood glucose conc., amino and fatty acids, glucagon (stimulant), somatostatin (inhibits), automatic nervous system and incretins (GIP and GLP)

Question 24

Characteristic of Type 2 Diabetes

Answer 24

High blood glucose >7 mmol/L while fasting (and also high insulin)

Question 25

Hyperglycemia Def.

Answer 25

Elevated blood glucose due to poor regulation

Question 26

Polyuria

Answer 26

Glucose in urine, resulting in increased urination

Question 27

Polydispa

Answer 27

Excessive thirst as result of polyuria

Question 28

2 Types of Diabetes Tests

Answer 28

HbA1c and Glucose Tolerance Tests

Question 29

HbA1c Def.

Answer 29

Measures glycosylated haemoglobin. Average blood glucose over 8-12 weeks. Normal (<5.7%), Prediabetic (5.7-6.4%) and diabetic (>6.5%)

Question 30

Glucose Tolerance Tests

Answer 30

75g of blood taken and glucose meaured over 2 hrs. 7.8-11 mmol/L (impaired glucose tolerance) and .11.1 mmol/L (diabetes)