The Endocrine Pancreas 1

Question 1

What is the function of the feeding centre?

Answer 1

promotes feelings of hunger and drive to eat

Question 2

Whats the function of the Satiety Centre?

Answer 2

promotes feelings of fullness by suppressing the Feeding Centre

Question 3

What is glucostatic theory?

Answer 3

Food intake determined by [BG], as it increases, drive to eat decreases

Question 4

What is lipostatic theory?

Answer 4

Food intake determined by fat stores, as they increase, drive to eat decreases

Question 5

What peptide hormone is released by fat stores to depress feeding?

Answer 5

Leptin

Question 6

What are the 3 categories of cellular work?

Answer 6

Cellular work
Mechanical work
Heat loss

Question 7

What are the 3 elements of human metabolism?

Answer 7

Extracting energy from nutrients
Storing said energy
Utilising said energy for work

Question 8

What are anabolic pathways?

Answer 8

Net effect is synthesis of large molecules from smaller ones

Question 9

What are catabolic pathways?

Answer 9

Breaking down large molecules to smaller ones - releasing energy

Question 10

What is an absorptive state?

Answer 10

After eating - ingested nutrients supply the energy needs of the body (anabolic)

Question 11

What is a fasted/post-absorptive state?

Answer 11

Between meals - body relies on stores for energy (catabolic)

Question 12

What has the first dibs on glucose?

Answer 12

The brain

Question 13

What is glycogenolysis?

Answer 13

Glycogen -> glucose

Question 14

What is gluconeogenesis?

Answer 14

Amino-acids -> Glucose

Question 15

How is excess glucose removed?

Answer 15

Via urine

Question 16

What hormone is essential for uptake of [BG]?

Answer 16

Insulin

Question 17

What is lipogenesis?

Answer 17

Turning excess glucose into fat stores

Question 18

What is the normal range of [BG]?

Answer 18

4.2-6.3mM

Question 19

Where is insulin produced?

Answer 19

Islet of Langerhans (pancreas)

Question 20

What do alpha cells produce?

Answer 20

Glucagon

Question 21

What do beta cells produce?

Answer 21

Insulin

Question 22

What do delta cells produce?

Answer 22

Somatostatin

Question 23

What do F cells produce?

Answer 23

Pancreatic polypeptide

Question 24

What are the effects of increased (dominant) insulin?

Answer 24

(glucose taken up by cells)
↑ Glucose oxidation
↑ Glycogen synthesis
↑ Fat synthesis
↑ Protein Synthesis

Question 25

What are the effects of increased (dominant) glucagon?

Answer 25

(glucose released into plasma) ↑ Glycogenolysis ↑ Gluconeogenesis ↑ Ketogenesis

Question 26

What type of hormone is insulin?

Answer 26

Peptide hormone

Question 27

Where is insulin made?

Answer 27

Beta cells in islets of langerhans

Question 28

How is insulin synthesised?

Answer 28

Preprohormone - Preproinsulin

Question 29

What is the fate of preproinsulin?

Answer 29

Converted into proinsulin in the endoplasmic reticulum

Question 30

What is the fate of proinsulin?

Answer 30

Packaged as granules in vesicles where it is cleaved into insulin and C-peptide and stored

Question 31

How is insulin unique relating to glucose?

Answer 31

It is the only hormone which lowers [BG]

Question 32

How does [BG] trigger insulin secretion from beta cells?

Answer 32

[BG] enters cells through GLUT and increases metabolism Increased [ATp} causes the Katp channel to close Closing the Katp channel causes ↑[K+], depolarising the cell This opens voltage gated Ca2+ channels Triggers vesicle exocytosis

Question 33

How does low [BG] trigger low insulin?

Answer 33

ATP is low so Katp channels are open, removing the K+, thus the +ve charge

Question 34

What does insulin bind to?

Answer 34

Kinase receptors on insulin sensitive tissues

Question 35

Insulin stimulates the mobilisation of what when bound?

Answer 35

GLUT-4 transporters to migrate to the membrane

Question 36

What types of tissue are insulin dependent?

Answer 36

Fat | Muscle

Question 37

Which GLUT transporters are NOT insulin dependent?

Answer 37

GLUT-1, 2, 3

Question 38

What is the role of GLUT-1?

Answer 38

Glucose uptake in brain, kidney, RBC

Question 39

What is the role of GLUT-2?

Answer 39

Glucose uptake in Pancreas, liver

Question 40

What is the role of GLUT-3?

Answer 40

Glucose uptake in brain, kidney, RBC

Question 41

How does the liver take up glucose?

Answer 41

GLUT-2 and 4 Glucose enters down the concentration gradient (transport into hepatocytes is affected by insulin)

Question 42

How does the liver continue to uptake glucose in a fed state?

Answer 42

Insulin activates Hexokinase which converts Glucose -> G-6-P | Relatively decreasing [Glucose]

Question 43

What is the role of the liver on [Glucose] in a fasted state?

Answer 43

Glucose synthesis (gluconeogenesis, glycogenolysis) which ↑[Glucose] causing it to move out the cell

Question 44

What is the non-anabolic role of insulin?

Answer 44

Promote K+ entry into cells stimulating Na+/K+ ATPase

Question 45

What are the anabolic roles of insulin?

Answer 45

``` Increase glycogen synthesis in muscles and liver Inhibit glycogen phosphorylase Increase AA uptake Promote protein synthesis Increase TAG synthesis Inhibit enzymes of gluconeogenesis ```

Question 46

What is the half life of insulin?

Answer 46

~5mins

Question 47

What happens to insulin after it completes its action?

Answer 47

Internalised with the receptors by endocytosis | Destroyed by insulin protease or recycled

Question 48

What are the stimuli which increase insulin release?

Answer 48

``` Increased [BG] Increased [Amino A]plasma Glucagon Incretin hormones controling GI secretion & motility Vagal nerve activity ```

Question 49

What are the stimuli which inhibit insulin release?

Answer 49

Low [BG] Somatostatin (GHIH) Sympathetic alpha2 effects Stress

Question 50

Why does oral loading glucose stimulate a larger insulin response than I.V glucose?

Answer 50

``` Increase insulin by effect on beta cells AND Vagal stimulation via anticipatory effect PLUS Incretin! ```