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09_Endocrine & Diabetes TC > Control of Metabolism & Biochemistry > Flashcards

Control of Metabolism & Biochemistry Flashcards

1
Q

Which centres of the hypothalamus determine energy intake?

2

A 
Feeding centre 
Satiety centre (insulin sensitive)
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2
Q

Which 2 theory’s describe food intake drive?

A

Glucostatic (Blood Glucose Levels)

Lipostatic (Leptin peptide hormone being released from fat stores decreases feeding)

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3
Q

What are the 3 classes of energy output?

A

Cellular work - Metabolism
Mechanical work - Movement / moving neurotransmitters
Heat loss - Associated with both above

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4
Q

Anabolic pathways

A

Synthesis large molecules

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5
Q

Catabolic pathways

A

Break down larger molecules

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6
Q

How is glucose synthesised

A 
Glycogen (glycigenisis) 
Amino acids (gluconeogensis)
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7
Q

What is the normal blood glucose range

A

4.2-6.3mM

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8
Q

Which are the 2 main hormones involved in the regulation of blood glucose levels

A

Insulin & Glucagon

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9
Q

What percent of the pancreas has endocrine function?

A

1% (Islets of Langerhans)

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10
Q

Whats are the cell types in Islets of Langerhans and what do they produce?

A

Alpha - Glucagon
Beta - Insulin
Delta - Somatostatin
F - Pancreatic polypeptide

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11
Q

What are the actions of Insulin dominance over Glucagon?
(High Blood Glucose Levels)
(4)

A

Increase in:

  • Glucose oxidation
  • Glycogen synthesis
  • Fat synthesis
  • Protein synthesis
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12
Q

What are the actions of Glucagon dominance over Insulin?
(Low Blood Glucose Levels)
(3)

A

Increase in:

  • Glycogenolysis
  • Gluconeogenesis
  • Ketogenesis
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13
Q

What type of hormone is Insulin

A

Peptide

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14
Q

What is used to measure beta cell function (inline production)?

A

C-Peptide Levels

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15
Q

What hormone other an insulin lowers blood glucose levels?

A

None

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16
Q

How can glucose be stored?

A

Glycogen in the liver

Triacylglycerols in liver and adipose tissue

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17
Q

What are the mechanisms of control of insulin secretion?

A

Increase of Blood glucose
Increases in glucose entering beta cells (GLUT)
Increase in metabolism
Increase in ATP
K+ ion channels in he beta cells are sensitive to ATP so close
Cells depolarise
Volted gated Ca channels open
Ca enters the cell triggering exocytosis of vesicles
Insulin is released

18
Q

What receptors does insulin bind to on muscle and adipose tissue?

A

Tyrosine Kinase Receptors

19
Q

What is the action of insulin binding to surface receptors

A

GLUT-4 transporters migrate from the cytoplasm to the cell membrane and becomes imbedded for the transport of glucose

20
Q

How does the GLUT-4 transport become attached to the cell membrane?

A

Insulin binds to receptors
Intracellular signalling cascade
GLUT4 migrates to membrane
GLUT-4 exocytosis into the cell membrane
Glucose enters the cell down the concentration gradient

21
Q

How do muscle and adipose tissues take up insulin in the absence of insulin?

A

Adipose - Can’t

Muscle - Can’t at rest but during exercise GLUT-4 transporters migrate independently of insulin

22
Q

Which tissues are insulin dependant?

A

Muscle (40% of body weight)

Fat (20-25% of body weight)

23
Q

What do other cells use to transport glucose?

A

Non insulin dependant GLUT transporters

24
Q

What cells use GLUT 1,2 & 3 transporters

A 
GLUT-1 = Brain, Kidney, RBCs and other tissues
GLUT-2 = Beta cells of pancreas & Liver (insulin can still help in liver)
GLUT-3 = Similar to GLUT-1
25
Q

How does insulin help the hepatocytes absorp glucose ?

A

Insulin stimulates hexokinase in liver cells
Signalling cascade
Tuns glucose into Glucose-6-phosphate
This reduces the concentration of glucose inside the cell
Increases the concentration gradient
More glucose enters the cell

26
Q

What are the additional actions of insulin?

A

Anabolic:
Increases glycogen synthesis in muscle and liver cells
Increases amino acid uptake (protein synthesis)
Inhibits proteolysis (protein metabolise)
Increases triacylglycerol synthesis in adipocytes
Inhibits gluconeogenesis in the liver

Hormones:
Has a permissive effect on growth hormone
Promotes K+ ion entry

27
Q

How does insulin increase glycogen synthesis?

A

Stimulates glycogen synthase and inhibits glycogen phosphorylase

28
Q

How long is Insulins half life?

A

5mins

29
Q

Where is Insulin broken down and by what?

A

Insulin bound receptors internalised by endocytosis and destroyed by insulin protease

Insulinase in liver and kidneys

30
Q

What increases insulin release?

A 
Increased BG
Increased Amino Acids 
Increased Glucagon (for the uptake of glucose following gluconeagenisis)
GI secretion & motility (CCK & secretin)
Vagal nerve
31
Q

What inhibits insulin release?

A

Low BG
Somatostatin
Sympathetic alpha effects*
Stress (hypoxia)*

*results of the sympathetic nervous system

32
Q

Why is more insulin released as a result of oral glucose rather than IV glucose intake?

A

Vagus + Incretin response on top of the usual direct effect on Beta cells

33
Q

What is the half life of Glucagon?

A

5-10mins

34
Q

Where are most Glucagon using cells found?

A

Liver

35
Q

What are the Glucagon receptors?

A

G-Protein coupled receptors

36
Q

What would the brain switch to in the absence of Glucose?

A

Ketone Bodies

37
Q

What are the three processes caused by Glucagon?

A
  • Glycogenesis (break down of Glycogen)
  • Glucaneogenasis (break down of amino acids)
  • Ketosis (Breakdown of adipose tissues)
38
Q

What would happen if Glucagon wasn’t secreted in a rise of amino acids?

A

Insulin would rise to absorb amino acids
Glucose would also be absorbed
Hypoglycaemia would occur

39
Q

What are the 4 hormones which respond to a low Blood glucose level?

A

Glucagon - Glycogenolysis (liver)
Epinehrine - Glycogenolysis (liver and muscle)
Cortisol - Protein catabolism & Inhibition of glucose uptake
Growth Hormone - Inhibition of glucose uptake

All promote Lipolysis & Gluconeogensis

40
Q

What is the main function of Somatostatin?

A

Inhibits activity in GI tract (slows down gastric motility absorption of nutrients)
Inhibits alpha and beta cells from secreting insulin and glucagon

41
Q

How does exercise effect insulin sensitivity?

A

Increases sensitivity for several hours post exercise

09_Endocrine & Diabetes TC (9 decks)

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