Pancreas

Question 1

What is the exocrine pancreas and what is its role?

Answer 1

Larger component of the pancreas that secretes digestive enzymes
Secretes bicarb

Question 2

What are the main digestive enzymes secreted by the pancreas?

Answer 2

Trypsin
Lipase
Amylase

Question 3

What are islets of langerhans cells?

Answer 3

Endocrine cells concentrated on islets
Beta
Alpha
Delta

Only make up 1-2% of pancreas

Question 4

What is the most common endocrine cell in the islets of langerhans?

Answer 4

Beta cells = 60-70%
Delta = only 10%

Question 5

Where is stomatostatin produced?

Answer 5

Hypothalamus
Stomach
Intestine
Delta cells of the pancreas

Question 6

What is the function of stomatostatin?

Answer 6

Paracrine function
Suppresses insulin and glucagon secretion from alpha and beta

Question 7

What kind of hormone is insulin?

Answer 7

Peptide hormone

Question 8

How is insulin synthesised?

Answer 8

Preprohormone-> prohormone (proinsulin)-> insulin

Question 9

Which hormone is secreted in equal amounts to insulin?

Answer 9

C- peptide
Secretion of insulin requires the removal of C- peptide from proinsulin
Biologically inactive

Question 10

Structure of insulin?

Answer 10

2 polypeptide chains
21 alpha 30 beta amino acids w 2 disulfide bonds

Question 11

How is insulin degraded?

Answer 11

In liver or kidney
Cleavage of disulfide bonds
Within target cells after receptor binding

Question 12

Insulin half life

Answer 12

5-8 minutes

Question 13

What is the route of insulin in the body?

Answer 13

Veins-> portal system -> portal vein to liver -> general circulation

Question 14

What are the 3 mechanisms for insulin regulation?

Answer 14

Nutrients
Gastrointestinal hormones (GIP, GLP-1)
PNS stimulates SNS inhibits

Question 15

Why is insulin an anabolic hormone?

Answer 15

Increased secretion when nutrients are abundant

Question 16

What transport mechanism is used by insulin to move energy substrates into storage?

Answer 16

Calcium mediated exocytosis

Question 17

Outline the GI hormonal stimulus for insulin

Answer 17

Insulin is stim by GIP and GLP-1 released from small intestinal cells
Inc GIP and GLP-1 when food reaches intestine = insulin from pancreas

Question 18

How does the PNS and SNS affect insulin secretion?

Answer 18

PNS - increases via vagal nerve as inc in GI motility
SNS - decreases via symp neurones - indirect response to adrenaline = hyperglycaemia

Question 19

What are the stages of insulin secretion?

Answer 19

1st phase = intracytoplasmic pool of proinsulin
2nd phase= Insulin secretion results from new protein synthesis

Question 20

What is GLUT2?

Answer 20

Islet glucose sensor

Question 21

What ions and transporters are involved in the release of insulin?

Answer 21

GLUT2
Calcium
Potassium
Glucose

Question 22

Outline beta cell events that lead to insulin release

Answer 22

inc blood glucose
GLUT2 allow glucose to enter
Phosphorylation of glucose by glucokinase
Inc ATP
Inhibits ATP potassium channels
Inc potassium in cell = depolarisation
voltage gated Ca channels open
Influx of Ca triggers exocytosis of insulin

Question 23

What pathway do insulin receptors activate?

Answer 23

Tyrosine kinase signal transduction pathway

Question 24

What is a determinant of insulin sensitivity?

Answer 24

Insulin receptor density

Question 25

How does glucose enter cell when facilitated by insulin?

Answer 25

GLUT4 (insulin dependent glucose transporter) Insuline stims GLUT4 proteins from cytoplasmic vesicles to membrane

Question 26

What is the action of insulin on carbohydrates in different tissues?

Answer 26

Muscle- Glucose uptake, Glycogenesis (glycogen synthase activity) Liver- stim glycogenesis, lipogenesis, GLUT2 glucose uptake Brain- GLUT1 glucose into cells, GLUT 4 only in satiety centres

Question 27

How does insulin impact fat metabolism?

Answer 27

Inhibits lipase = inhibits lipolysis Stims de novo lipogenesis (production of fatty acids from glucose) Promotes lipoprotein lipase= more FA into tissues

Question 28

How does insulin impact protein metabolism?

Answer 28

Inc AA into tissues Inc rate of protein synthesis Inhibits catabolism of proteins Dec gluconeogenesis by lowering AA supply

Question 29

What are the properties of glucagon?

Answer 29

Secreted by alpha cells 29 amino acid peptide hormone Synth as preproglucagon

Question 30

What is the plasma half life of glucagon?

Answer 30

5-6 minutes

Question 31

Where is glucagon metabolised?

Answer 31

Liver and kidneys

Question 32

What is the action of glucagon?

Answer 32

Catabolic hormone Works mainly in the liver Maintains blood glucose levels in interprandial period Activated during negative energy balance Inc glycogenolysis and gluconeogenesis

Question 33

What is the action of glycogen synthase?

Answer 33

Activated by insulin and increases glycogen production

Question 34

What is the action of glycogen phosphorylase?

Answer 34

Activated by glucagon and increases glucose production

Question 35

How is glucagon secreted?

Answer 35

Blood glucose decreases glucagon secretion increases Stim by high AA (alanine and arginine) = promotes gluconeogenesis Post prandial hypoglycemia protection - aas of meal would cause low glucose

Question 36

When does negative energy balance occur?

Answer 36

Demand exceeds supply

Question 37

Which hormones increase in the blood as a result of feed deprivation?

Answer 37

Glucagon Cortisol Epinephrine growth hormone

Question 38

In negative energy balance what storage of lipid is broken down?

Answer 38

Triglycerides into glycerol and 3 FA

Question 39

In what process do fatty acids generate energy?

Answer 39

Beta oxidation - occurs in mitochondria of the liver

Question 40

What is the end product of beta oxidation?

Answer 40

Acetyl co A = enters the TCA cycle or converted to ketones

Question 41

When are ketones produced?

Answer 41

when fatty acids are being mobilised from adipose tissues If oxaloacetate is low then more acetyl co A from beta oxidation is diverted to ketone production

Question 42

Simple process of ketosis?

Answer 42

Inc in FA + decrease in glucose= increase in ketones

Question 43

What are the 3 ketones?

Answer 43

Acetoacetate Beta hydroxybutyrate Acetone

Question 44

Which ketone is removed from the body via the respiratory tract?

Answer 44

Acetone

Question 45

A resistance to which hormone, will increase ketosis?

Answer 45

Insulin Because HSL is enhanced as insulin is not suppressing HSL

Question 46

How does DM affect lipid mobilisation from adipose stores?

Answer 46

Increases mobilisation as HSL is not inhibited by insulin

Question 47

How does diabetic ketoacidosis occur?

Answer 47

Less insulin so more HSL Inc mobilisation of FA and decreased oxaloacetate availability Clin signs Diarrhoea, vomiting anorexia and dehydration