The endocrine pancreas

Question 1

Give a summary of the glucostatic theory

Answer 1

Our drive to eat is driven by our glucose levels

Question 2

Give a summary of lipostatic theory

Answer 2

Our drive to eat is driven by fat stores

Question 3

What is the function of leptin

Answer 3

Peptide hormone driven by fat stores which depresses feeding activity through its affect on the hypothalamus

Question 4

What are the 3 categories of energy output

Answer 4

cellular work - transporting molecules across membranes, growth and repair, storage of energy

mechanical work - movement using muscle

heat loss - associated with cellular and mechanical work

Question 5

what are Anabolic pathways

Answer 5

Building up of larger molecules from smaller ones
(remember anabolic steroids - build up muscle therefore anabolic pathways build up bigger molecules)

Question 6

What are catabolic pathways

Answer 6

Degradation of large molecules into smaller ones which releases energy

Question 7

What is an absorptive state

Answer 7

Ingested nutrients supply the energy the body needs and the the excess is stored (anabolic phase)

Question 8

When does an absorptive state occur

Answer 8

After eating

Question 9

What is a post absorptive state

Answer 9

(fasting state)
Rely on body stores to provide energy (catabolic phase)

Question 10

When does a post absorptive state occur

Answer 10

Between meals and overnight

Question 11

What does it mean to be an obligatory glucose utiliser and give an example

Answer 11

It can only use glucose for energy for example the brain

Question 12

What is the normal range of blood glucose

Answer 12

3.2-6.3 mM

Question 13

What organ has first access to glucose in the blood

Answer 13

The brain

Question 14

What is excess glucose converted into

Answer 14

fat stores or glycogen

Question 15

What is glucagon

Answer 15

Catabolic hormone which breaks down glycogen stores and activates enzymes to break down amino acids into glucose

Question 16

What is insulin

Answer 16

Anabolic hormone which stimulates production of fat and glycogen from glucose

Question 17

Why is glucose excreted in the urine in diabetics

Answer 17

They don’t have enough insulin to deal with increased blood glucose levels so when the blood gets to the glomerulus, the kidneys have too much glucose to deal with so the excess gets excreted

Question 18

What organ releases insulin and glucagon

Answer 18

pancreas

Question 19

How much of the pancreas has endocrine function and where in the pancreas are insulin and glucagon produced

Answer 19

1% is endocrine and insulin and glucagon are produced in the islets of langerhans

Question 20

What do alpha cells of the islets of langerhans produce

Answer 20

glucagon

Question 21

What do the beta cells of the islets of langerhans produce

Answer 21

insulin

Question 22

What do the delta cells of the islets of langerhans produce

Answer 22

Somatostatin

Question 23

When is glucagon released into the plasma

Answer 23

When the blood glucose levels decrease

Question 24

When is insulin released into the plasma which causes glucose to be up taken into cells to decrease plasma blood glucose

Answer 24

When the blood glucose in the plasma is very high
And when amino acids enter the blood from the GI tract

Question 25

Describe how insulin is synthesised

Answer 25

It is synthesised as a large preprohormone - preproinsulin which is then converted into proinsulin Proinsulin is then packaged into secretory Vesicles which has enzymes which cleave the proinsulin into insulin and C peptide insulin

Question 26

Why os C peptide a good marker for pancreatic health

Answer 26

it resists degradation and persists in the plasma, longer than insulin

Question 27

Which hormone dominates the absorptive state

Answer 27

Insulin (anabolic)

Question 28

What is glucose stored as in liver and muscle

Answer 28

Glycogen

Question 29

What is glucose stored as in liver and adipose tissue

Answer 29

Triacylglycerols

Question 30

What causes beta cells to release insulin

Answer 30

They have a special Katp channel which is sensitive to ATP When glucose is abundant, it enters cells through the GLUT transported and metabolism increases which causes more ATP to be produced in the cell which causes the channel to close. Intracellular potassium then rises which depolarises the cell which causes voltage gated calcium channels to open and triggers insulin to be exycytosed from their vesicles to be released into the circulation

Question 31

What is the primary action of insulin

Answer 31

Binds to tyrosine kinase receptors on the cell membrane of insulin dependent tissues to increase the glucose uptake in that cell

Question 32

How does insulin increase glucose uptake in cells

Answer 32

Mobilisation of GLUT-4 which is normally in the cytoplasm but migrates to the membrane which allows more glucose to be up taken into the cell

Question 33

What are the insulin dependent cell types

Answer 33

Muscle and fat

Question 34

What GLUT transporter is insulin dependant

Answer 34

GLUT-4

Question 35

What transporter does the liver use for glucose uptake

Answer 35

GLUT 2 which is insulin independent

Question 36

How does insulin indirectly alter glucose transport in hepatocytes

Answer 36

It breaks down glucose into glucose-6-phosphate which keeps the glucose concentration in the hepatocyte low which maintains the gradient for more glucose to enter the cell

Question 37

What is the effect of insulin on glycogen synthesis in muscle and liver

Answer 37

Stimulates glycogen synthesis and inhibits glycogen phosphorylase

Question 38

What is the effect of insulin on amino acid uptake

Answer 38

Increases it which promotes protein synthesis

Question 39

What is the effect of insulin on triaglycerol synthesis

Answer 39

Increases it in adipocytes and liver by stimulating lipogenesis

Question 40

What is the effect of insulin on gluconeogenesis in the liver

Answer 40

inhibits it

Question 41

What is the relation between insulin and growth hormone

Answer 41

Permissive effect - insulin is required for Growth hormone to be active and working

Question 42

What is the effect of insulin on potassium entry

Answer 42

Stimulates sodium potassium ATPase so increases potassium entry into the cell

Question 43

What happens to insulin receptors after the effects of insulin are completed

Answer 43

The receptors are endocytosed and destroyed by insulin protease

Question 44

Why does glucose given orally cause bigger release of insulin then IV glucose

Answer 44

Because the release of GI hormones causes release of insulin as well as blood glucose and in IV glucose these hormones will not be released

Question 45

What is the effect of vagal activity on insulin release

Answer 45

Increased vagal activity causes insulin release

Question 46

What is the main target organ for glucagon

Answer 46

Liver

Question 47

What are the hormones which are part of the glucose counter-regulatory system

Answer 47

Epinephrine, cortisol, growth hormone and glucagon

Question 48

What does glucagon cause

Answer 48

Increased glycogenolysis Increased gluconeogenesis Formation of ketones from fatty acids

Question 49

What does the brain use instead of glucose in severe cases of starvation

Answer 49

Ketones

Question 50

What are potent stimulus for glucagon secretion

Answer 50

Amino acids but they also increase insulin levels

Question 51

What is the effect of somatostatin on insulin and glucose release

Answer 51

Somatostatin inhibits both glucagon and insulin release

Question 52

Why do cushings patients appear diabetic

Answer 52

They have high cortisol which inhibits insulin

Question 53

What is the main function of somatostatin

Answer 53

Inhibit the GI tract

Question 54

What occurs if insulin and glucagon are both inhibited

Answer 54

Blood glucose rises as there are multiple hormones which increase blood glucose but only insulin reduces blood glucose

Question 55

What is the effect of insulin on glucagon

Answer 55

Inhibits glucagon

Question 56

What is the effect of glucagon on insulin

Answer 56

stimulates insulin release

Question 57

What is the effect of exercise on blood glucose

Answer 57

Decreases blood glucose because it increases glucose entry into muscle cells even in absence of insulin which causes increase in GLUT-4 transporters It also increases insulin sensitivity

Question 58

What happens during starvation with regards to production of energy

Answer 58

Adipose tissue is broken down and fatty acids are released - these are readily used by most tissues to produce energy

Question 59

What does the liver convert free fatty acids into during starvation

Answer 59

Ketone =bodies which can be used by muscle and brain

Question 60

What is ketone body uptake dependant on

Answer 60

insulin

Question 61

What happens in type one diabetes

Answer 61

Autoimmune destruction of the pancreatic beta cells of the islets of langerhans which compromises ability to produce insulin

Question 62

What do type one patients have an absolute need for

Answer 62

Insulin - without it they become excessively wasted and develop ketoacidosis

Question 63

How does ketoacidosis occur in type 1 diabetes

Answer 63

No insulin results in a starvation like state due to glucose not being up taken into cells This results in adipose being broken down into fatty acids and the excess free fatty acids converted into ketone bodies Ketone bodies rely on insulin for their up take so without the insulin they stay in the plasma and due to their acidity cause acidosis

Question 64

How are ketones detected

Answer 64

In the urine and can smell acetone in the breath

Question 65

What happens in type 2 diabetes

Answer 65

Peripheral tissues become insensitive to insulin

Question 66

What is type 2 diabetes associated with

Answer 66

obesity - chronic levels of exposure of high insulin due to their high glucose diets - this eventually builds an insulin resistance

Question 67

How is diabetes detected

Answer 67

Glucose tolerance test - patients ingest glucose after fasting blood glucose is measured - the blood glucose should return to normal fasting levels within an hour - anything over 2 hours is indicative of diabetes