Pancreas

Question 1

what does the feeding centre promote?

Answer 1

feelings of hunger and a drive to eat

Question 2

what does the satiety centre promote?

Answer 2

feelings of fullness (by suppressing the feeding centre)

Question 3

describe the glycostatic theory controlling the energy intake

Answer 3

food intake is determined by the blood glucose. as it increases the drive to eat decreases.

Question 4

describe the lipostatic theory controlling energy intake

Answer 4

food intake is determined by fat stores. as fat stores increase the drive to eat decreases.

Question 5

what is leptin?

Answer 5

a peptide hormone released by fat stores to depress feeding centres

Question 6

what are the three categories of energy output?

Answer 6

> cellular work
mechanical growth
heat loss

Question 7

what is metabolism?

Answer 7

integration of all biochemical reactions in the body

Question 8

what is the net effect in anabolic pathways?

Answer 8

synthesis of large molecules from smaller ones usually for storage purposes

Question 9

what is the absorptive state?

Answer 9

the state we enter after eating a meal where digested nutrients supply the energy needs of the body and excess is stored

Question 10

what is the net effect in catabolic pathways?

Answer 10

there is breakdown of large molecules into smaller ones, releasing energy for work

Question 11

what is the post-absorptive state?

Answer 11

where we really on body stores to provide energy as the nutrients in the plasma decrease.

Question 12

what is glycogenolysis?

Answer 12

making glucose from glycogen

Question 13

what is gluconeogenesis?

Answer 13

making glucose from amino acids

Question 14

what is glycogenesis?

Answer 14

making glycogen from glucose

Question 15

what is the normal range for glucose?

Answer 15

4.2-6.3mM

Question 16

name the 4 cell types in the islets of Langerhans

Answer 16

> alpha cells
beta cells
delta cells
F cells

Question 17

what do alpha cells produce?

Answer 17

glucagon

Question 18

what do beta cells produce?

Answer 18

insulin

Question 19

what do delta cells produce?

Answer 19

somatostatin

Question 20

what do f cells produce?

Answer 20

pancreatic polypeptide (help nutrient absorption from GI)

Question 21

where is preproinsulin converted to proinsulin?

Answer 21

in the rough endoplasmic reticulum in beta cells

Question 22

what is proinsulin split into?

Answer 22

> insulin

> c peptide

Question 23

what is the effect of insulin on excess glucose stored?

Answer 23

> as glycogen in the liver and muscles

> as triacylglycerols in the liver and adipose

Question 24

what is the effect of insulin secretion on amino acids?

Answer 24

they are made into new proteins and the excess is converted to fat

Question 25

what is the effect of insulin secretion on fatty acids?

Answer 25

they are stored in the form of triglycerides in the adipose tissue and liver

Question 26

what triggers insulin secretion?

Answer 26

high glucose levels in the blood

Question 27

how is metabolism affected by insulin?

Answer 27

it is increased

Question 28

describe how glucose causes insulin secretion

Answer 28

> glucose enters the cell through a GLUT transporter > it increases cellular ATP > this ATP causes the cell to depolarise > this opens Ca2+ channels which acts as an intracellular signal > this triggers exocytosis and secretion of insulin

Question 29

describe the action of insulin on a cell

Answer 29

> insulin binds to a tyrosine kinase receptor > signal transduction cascade mobilises GLUT4 which migrates to the membrane > glucose is transported into the cell

Question 30

what happens to GLUT4 transporters when insulin stimulation stops?

Answer 30

they return to the cytoplasmic pool

Question 31

what receptor does insulin bind to?

Answer 31

tyrosine kinase receptor

Question 32

what cells are sensitive to insulin?

Answer 32

muscle and fat cells

Question 33

what transporters are involved in non-insulin dependent glucose uptake?

Answer 33

GLUT 1, 3 and 2

Question 34

what are glut 1 and 3 transporters used for?

Answer 34

basal glucose uptake in tissues like the brain, kidney and RBC

Question 35

what cells take up glucose via GLUT 2?

Answer 35

> beta cells of the pancreas | > liver cells

Question 36

how does insulin indirectly alter glucose transport?

Answer 36

insulin activates hexokinase which lowers intracellular glucose concentration creating a gradient that moves glucose into cells.

Question 37

what hormone is insulin permissive to?

Answer 37

growth hormone

Question 38

what is the effect of insulin of potassium ion entry to the cell?

Answer 38

insulin stimulates Na/K ATPase allowing potassium to enter the cell.

Question 39

what stimulates insulin release?

Answer 39

``` > vagal nerve activity > increased amino acids > increased blood glucose concentration > glucagon > incretin hormones controlling GI secretion and motility ```

Question 40

what inhibits insulin release?

Answer 40

> low [BG] > somatostatin > sympathetic alpha2 effects > stress (hypoxia)

Question 41

is IV glucose load more or less than the equivalent amount of glucose given orally?

Answer 41

it is less: | oral glucose increases insulin by direct effect on beta cells AND vagal stimulation of beta cells AND incretin effects

Question 42

what are the effects of glucagon?

Answer 42

increased: > gycogenolysis > gluconeogenesis > ketogenesis

Question 43

what cells produce glucagon?

Answer 43

alpha cells

Question 44

at what blood glucose level will secretion of glucagon increase dramatically?

Answer 44

<5.6mM

Question 45

what stimulates glucagon secretion?

Answer 45

``` > stress > cortisol > low [BG] > high [amino acid] > sympathetic innervation (epinephrine) ```

Question 46

what inhibits glucagon release?

Answer 46

``` > glucose > free fatty acids > ketones > insulin > somatostatin ```

Question 47

what cells in the pancreas produce somatostatin?

Answer 47

D cells

Question 48

what is the main pancreatic function of somatostatin?

Answer 48

inhibition of activity in the GI tract: slowing down absorption of nutrients to prevent exaggerated peaks in plasma concentration

Question 49

what is the effect of somatostatin on insulin and glucagon?

Answer 49

it supresses the release of these hormones in a paracrine fashion

Question 50

what is the effect of exercise on insulin sensitivity?

Answer 50

it increases sensitivity

Question 51

true or false: | in type 2 diabetes there can be hyperinsulineamia

Answer 51

true: beta cells ca remain intact so will continue to produce lots of insulin to try and over come the desensitisation of peripheral tissues

Question 52

does a glucose tolerance test distinguish between type 1 an 2 diabetes?

Answer 52

no it doesn't