The Endocrine Pancreas 1

Question 1

what is the Glucostatic theory

Answer 1

food intake is determined by blood glucose: as [BG] increases, the drive to eat decreases

Question 2

what is the lipostatic theory

Answer 2

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

Question 3

what is leptin

Answer 3

Leptin is a peptide hormone released by fat stores which depresses feeding activity.

Question 4

what is the only part of energy output we can regulate voluntarily

Answer 4

mechanical work done by skeletal muscle

Question 5

define the term metabolism

Answer 5

integration of all biochemical reactions in the body

Question 6

what is the absorptive state

Answer 6

After eating we enter an Absorptive State where ingested nutrients supply the energy needs of the body and excess is stored. This is an anabolic phase

Question 7

what is the post absorptive state

Answer 7

Between meals and overnight the pool of nutrients in the plasma decreases and we enter a Post-absorptive State (aka Fasted State) where we rely on body stores to provide energy. This is a catabolic phase

Question 8

the body MUST maintain blood glucose concentration [BG] sufficient to meet the brain’s requirements how is this done

Answer 8

BG is maintained by synthesising glucose from glycogen (glycogenolysis) or amino acids (gluconeogensis)

Question 9

what is the normal range of [BG]

Answer 9

4.2-6.3mM (5mmoles useful to remember)

Question 10

what [BG] level is considered hypoglycaemia

Answer 10

[BG] < 3mM

Question 11

where are insulin and glucagon produced

Answer 11

pancreas

Question 12

the pancreas releases NaHCO3 true or false

Answer 12

true

Question 13

what percentage of the pancreas has endocrine function

Answer 13

1% the rest operates as an exocrine gland

Question 14

there are 4 types of ilet cells what are they

Answer 14

alpha, beta, delta and F cells

Question 15

what do alpha cells produce

Answer 15

Glucagon

Question 16

what do beta cells produce

Answer 16

insulin

Question 17

what do delta cells produce

Answer 17

somatostatin

Question 18

what do F cells produce

Answer 18

pancreatic polypeptide

Question 19

what is the function of pancreatic polypetide

Answer 19

not known, may help control of nutrient absorption from GIT

Question 20

what type of hormone is insulin

Answer 20

peptide

Question 21

what is the function of insulin

Answer 21

stimulates glucose uptake by cells

Question 22

where is preproinsulin converted to proinsulin

Answer 22

in the ER

Question 23

what is the major stimulus for insulin secretion

Answer 23

blood glucose concentration

Question 24

what is the only hormone which lowers [BG]

Answer 24

insulin

Question 25

where is excess glucose stored

Answer 25

stored as glycogen in the liver and muscle. Stored as TAG in liver and adipose tissue

Question 26

what are amino acids mainly used for

Answer 26

mainly used to make new proteins (excess converted to fat)

Question 27

what form are fatty acids stored as

Answer 27

triglycerides (TAG) in adipose tissue and liver

Question 28

B-cells have a specific type of K+ ion channel that is sensitive to the ATP within the cell, what is it called

Answer 28

K ATP channel

Question 29

what are GLUT's

Answer 29

glucose transporter proteins

Question 30

what causes K ATP channels to close

Answer 30

the channels close when glucose enters into the cell and causes an increase in ATP within the cell

Question 31

what happens when K ATP channels close

Answer 31

intracellular K+ rises, depolarising the cell, voltage dependant ca2+ channels open and trigger insulin vesicle exocytosis into circulation

Question 32

when are K ATP channels open

Answer 32

when [BG] is low, ATP is low and K ATP channels will be open

Question 33

why is insulin not secreted when K ATP channels are open

Answer 33

as K+ ions will be flowing out hyperpolarising the cells, so voltage Ca2+ channels remain closed and insulin is not secreted

Question 34

what receptors does insulin bind to

Answer 34

tyrosine kinase receptors

Question 35

what are the insulin sensitive tissues

Answer 35

muscle and adipose tissue

Question 36

insulin stimulates the mobilization of specific glucose transporters, what are they called

Answer 36

GLUT-4

Question 37

where do GLUT-4 receptors reside

Answer 37

in the cytoplasm of unstimulated muscle and adipose tissue

Question 38

most types of tissue do NOT require insulin to take up glucose, what 2 tissues requires insulin to take up glucose

Answer 38

muscle and fat

Question 39

in tissues that don't require insulin how is glucose taken up into the cell

Answer 39

glucose uptake is via other GLUT-transporters, which are NOT insulin-dependent

Question 40

where would you find GLUT-2 receptors

Answer 40

Beta cells of pancreas and the liver

Question 41

what glucose transporters take up glucose into the liver

Answer 41

GLUT 2 (insulin independent)

Question 42

in the fed state the liver takes up glucose why

Answer 42

glucose moves down the concentration gradient. In the fed state insulin activates hexokinase which lowers glucose concentration in the cell, so glucose moves into the cell.

Question 43

insulin increases amino acid uptake into muscle promoting protein synthesis true or flase

Answer 43

true, this is one of the additional actions of insulin

Question 44

what is insulins effect on growth hormone

Answer 44

insulin has a permissive effect on growth hormone

Question 45

how does insulin promote K+ ion entry into cells

Answer 45

by stimulating Na+/K+ ATPase

Question 46

what is the half life of insulin

Answer 46

5 mins

Question 47

where is insulin principally degraded

Answer 47

in the liver and kidneys

Question 48

once insulin action is complete what happens to insulin bound receptors

Answer 48

they are internalised by endocytosis and destroyed by insulin protease, some recycled

Question 49

what are the stimuli which increase insulin release

Answer 49

1.increased [BG], 2.increased amino acids, 3.glucagon, hormones controlling GI secretion and motility, vagal nerve activity

Question 50

what are stimuli which inhibit insulin release

Answer 50

low [BG], somatostatin(GHIH), sympathetic a2 effects, stress e.g hypoxia