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Veterinary medicine year 2 > Pancreas > Flashcards

Pancreas Flashcards

1
Q

What is the exocrine pancreas and what is its role?

A

Larger component of the pancreas that secretes digestive enzymes
Secretes bicarb

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2
Q

What are the main digestive enzymes secreted by the pancreas?

A

Trypsin
Lipase
Amylase

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3
Q

What are islets of langerhans cells?

A

Endocrine cells concentrated on islets
Beta
Alpha
Delta

Only make up 1-2% of pancreas

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4
Q

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

A

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

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5
Q

Where is stomatostatin produced?

A

Hypothalamus
Stomach
Intestine
Delta cells of the pancreas

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6
Q

What is the function of stomatostatin?

A

Paracrine function
Suppresses insulin and glucagon secretion from alpha and beta

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7
Q

What kind of hormone is insulin?

A

Peptide hormone

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8
Q

How is insulin synthesised?

A

Preprohormone-> prohormone (proinsulin)-> insulin

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9
Q

Which hormone is secreted in equal amounts to insulin?

A

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

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10
Q

Structure of insulin?

A

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

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11
Q

How is insulin degraded?

A

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

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12
Q

Insulin half life

A

5-8 minutes

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13
Q

What is the route of insulin in the body?

A

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

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14
Q

What are the 3 mechanisms for insulin regulation?

A

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

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15
Q

Why is insulin an anabolic hormone?

A

Increased secretion when nutrients are abundant

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16
Q

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

A

Calcium mediated exocytosis

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17
Q

Outline the GI hormonal stimulus for insulin

A

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

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18
Q

How does the PNS and SNS affect insulin secretion?

A

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

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19
Q

What are the stages of insulin secretion?

A

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

20
Q

What is GLUT2?

A

Islet glucose sensor

21
Q

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

A

GLUT2
Calcium
Potassium
Glucose

22
Q

Outline beta cell events that lead to insulin release

A

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

23
Q

What pathway do insulin receptors activate?

A

Tyrosine kinase signal transduction pathway

24
Q

What is a determinant of insulin sensitivity?

A

Insulin receptor density

25
Q

How does glucose enter cell when facilitated by insulin?

A

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

26
Q

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

A

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

27
Q

How does insulin impact fat metabolism?

A

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

28
Q

How does insulin impact protein metabolism?

A

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

29
Q

What are the properties of glucagon?

A

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

30
Q

What is the plasma half life of glucagon?

A

5-6 minutes

31
Q

Where is glucagon metabolised?

A

Liver and kidneys

32
Q

What is the action of glucagon?

A

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

33
Q

What is the action of glycogen synthase?

A

Activated by insulin and increases glycogen production

34
Q

What is the action of glycogen phosphorylase?

A

Activated by glucagon and increases glucose production

35
Q

How is glucagon secreted?

A

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

36
Q

When does negative energy balance occur?

A

Demand exceeds supply

37
Q

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

A

Glucagon
Cortisol
Epinephrine
growth hormone

38
Q

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

A

Triglycerides into glycerol and 3 FA

39
Q

In what process do fatty acids generate energy?

A

Beta oxidation - occurs in mitochondria of the liver

40
Q

What is the end product of beta oxidation?

A

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

41
Q

When are ketones produced?

A

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

42
Q

Simple process of ketosis?

A

Inc in FA + decrease in glucose= increase in ketones

43
Q

What are the 3 ketones?

A

Acetoacetate
Beta hydroxybutyrate
Acetone

44
Q

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

A

Acetone

45
Q

A resistance to which hormone, will increase ketosis?

A

Insulin
Because HSL is enhanced as insulin is not suppressing HSL

46
Q

How does DM affect lipid mobilisation from adipose stores?

A

Increases mobilisation as HSL is not inhibited by insulin

47
Q

How does diabetic ketoacidosis occur?

A

Less insulin so more HSL
Inc mobilisation of FA and decreased oxaloacetate availability

Clin signs
Diarrhoea, vomiting anorexia and dehydration

Veterinary medicine year 2 (23 decks)

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