1a Glucose Homeostasis

Question 1

What is significantly impaired when glucose concentration falls below normal levels?

Answer 1

Cerebral function

Question 2

What is glucose particularly important for?

Answer 2

The functioning of the central nervous system

Question 3

What is hypoglycemia?

Answer 3

Blood glucose concentration levels fall below a normal levels

Question 4

What can happen is blood glucose Concentration falls below 2mmol/L

Answer 4

Unconsciousness, coma and ultimately death

Question 5

What does persistent hyperglycemia result in?

Answer 5

Diabetes mellitus

Question 6

What hormones act against hypoglycemia?

Answer 6

Glucagon
Cortisol
Growth hormone
Catecholamines

Question 7

What is the most prevalent form of diabetes?

Answer 7

Type 2 diabetes mellitus

Question 8

What are the three types of diabetes

Answer 8

Type 1 DM
Type 2 DM
maturity onset diabetes of the young

Question 9

What is meant by a retroperitoneal structure?

Answer 9

Has a peritoneum on the anterior side only

Question 10

What are the small clumps of cells in the pancreas called?

Answer 10

Islets of Langerhans

Question 11

What are exocrine acinar cells?

Answer 11

Cells that generate exocrine secretions

Question 12

What are the three types of islet cells?

Answer 12

Alpha, beta and delta cells

Question 13

What are the alpha cells involved with?

Answer 13

Glucagon secretion

Question 14

What are the beta cells in the islets of langerhans involved with?

Answer 14

Insulin secretion

Question 15

What are the delta cells in the islet of langerhans involved with?

Answer 15

Somatostatin secretion

Question 16

What are gap junctions?

Answer 16

They allow small molecules to pass directly between cells

Question 17

What are tight junctions?

Answer 17

Create small intercellular spaces

Question 18

What type of communication is found between the islet cells?

Answer 18

Paracrine communication

Question 19

What does insulin do?

Answer 19

Stimulates growth and development and reduces blood glucose

Question 20

What affect does insulin secreted from the beta cells have?

Answer 20

Increased:
- Glycolysis
- Glycogenesis
- Glucose transport into cells via GLUT 4

Question 21

Where is GLUT 4 predominantly expressed?

Answer 21

Adipocytes and skeletal muscle

Question 22

When blood glucose is high, what is released?

Answer 22

Insulin from the beta cells as well as some glucagon from the alpha cells to ensure that hypoglycaemia doesn’t occur

Question 23

Aside from glucose effects, what else does insulin do?

Answer 23

Increase amino acid transport, protein synthesis and lipogenesis

Decrease in lipolysis

Question 24

What is released when blood glucose levels are lowered?

Answer 24

Alpha cells release glucagon

Question 25

What affect does glucagon have?

Answer 25

INCREASED: - gluconeogenesis - lipolysis - blood glucose - amino acid transport to the liver - hepatic glycogenolysis

Question 26

Is GLUT 2 insulin sensitive?

Answer 26

No

Question 27

What is the main glucose sensor?

Answer 27

Glucokinase (hexokinase as IV)

Question 28

What is GLUT 2’s affinity for glucose, and what does this mean?

Answer 28

High affinity for glucose, so whatever glucose is in our blood stream is therefore reflected in the intracellular concentration of the beta cell

Question 29

Does glucose 6 phosphate inhibit glucokinase?

Answer 29

No

Question 30

Why do glucose 6 phosphate levels give a good indication of glucose levels as well?

Answer 30

Glucose to glucose 6 phosphate is a continual conversion by glucokinase therefore the amount of glucose present is equal to glucose 6 phosphate

Question 31

How is insulin released?

Answer 31

The ATP produced from glycolysis inhibits the potassium ion channels, meaning K+ remains in the beta cells therefore, there is an intracellular influx of Ca2+ which triggers the insulin to be released from the beta cells

Question 32

What is meant by a graded response of insulin production?

Answer 32

Insulin isn’t released in an all or nothing manner, continually released when needed and the amount released changes over time

Question 33

What is pro insulin cleaved into?

Answer 33

Pro insulin and C-peptide

Question 34

What happens to C peptide levels after a big meal?

Answer 34

Increase

Question 35

What happen to someone’s C peptide levels when a person with type 1 diabetes eats a meal?

Answer 35

They are low - this is because C peptide levels are only a measure of endogenous insulin, and doesn’t include the insulin which they have injected following the meal

Question 36

What is the difference between oral and intravenous glucose in terms of plasma insulin production? And what is this effect called?

Answer 36

Oral is significantly higher - increatin effect

Question 37

Transcription of what gene produced Glucagon like peptide 1?

Answer 37

Pro-glucagon gene

Question 38

Where is glucagon like peptide found?

Answer 38

In the gut

Question 39

What is the effect of glucagon like peptide 1?

Answer 39

Stimulated insulin and suppresses glucagon

Question 40

What effect does glucagon like peptide1 do to us?

Answer 40

Increases feeling of fullness

Question 41

Wh6 does GLP1 have a short half life?

Answer 41

Rapidly degraded by enzymes dipeptidyl peptidase 4

Question 42

What is GLP1 used in the treatment of?

Answer 42

Diabetes mellitus

Question 43

What is meant by the first phase insulin release?

Answer 43

This is following a meal, when a diabetics insulin levels do increase slightly, but much less than a healthy individuals, and stay elevated

Question 44

How does the insulin receptor work?

Answer 44

1. Insulin binds to alpha subunit 2. Causes a confirmation change in the tyrosine kinase domain of the beta sun unit 3. This causes the movement of GLUT 4 from intracellular space to cell membrane so glucose can be absorbed

Question 45

What part of the insulin receptor does insulin initially bind to?

Answer 45

Extracellular domain - alpha subunit

Question 46

What percentage of the pancreas gland is involved in exocrine secretions?

Answer 46

98%

Question 47

Where may you find insulin receptors?

Answer 47

Liver, muscle and fat

Question 48

What is the incretin effect?

Answer 48

When the production of plasma insulin is significantly larger and higher following giving oral glucose to patients