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P1: Endo > Endocrine Control Of Metabolism > Flashcards

Endocrine Control Of Metabolism Flashcards

1
Q

What process is at the core of energy metabolism?

A

→ TCA cycle

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2
Q

What do molecules have to be metabolized into to be fed into the TCA?

A

→ acetyl CoA

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3
Q

What are 5 circulating nutrients?

A 
→ Glucose
→ Fatty acids
→ Amino acids
→ Ketone bodies
→ Lactate
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4
Q

What are 3 stored nutrients?

A

Glycogen
→ Triglycerides
→ Body proteins

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5
Q

What is the level of plasma glucose?

A

→ 5 mmol / L

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6
Q

What energy source does the brain use?

A

→ glucose metabolism

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7
Q

What can the blood glucose level not drop below?

A

→ < 2.5. mmol

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8
Q

What is the ultimate outcome of hypoglycaemia?

A

→ coma and death

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9
Q

What does chronic exposure to high glucose concentrations cause?

A

→ Protein damage via non-enzymatic glycation

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10
Q

How much of body weight is water and how much of this is ECF and ICF?

A

60% total
→ 40% ICF
→ 20% ECF

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11
Q

How much glucose does the brain and muscle use up?

A

→ 30 mmol per hour

300 mmol per hour during intense exercise

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12
Q

What are the two sources of plasma glucose?

A

→ Diet

→ Organs that can export glucose into the circulation

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13
Q

What prevents plasma glucose from surging or plummeting?

A

→hormones regulate the integration of fat, carbs and protein metabolism
→ maintain constant blood plasma glucose

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14
Q

What are the 2 phases of metabolism?

A

→ Absorptive and fasting

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15
Q

What does insulin promote?

A

→ Storage

→ Decreases plasma glucose

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16
Q

What are the counter regulatory hormones to insulin?

A

Glucagon
→ Adrenaline
→ Cortisol + growth hormone

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17
Q

What does insulin stimulate?

A

→ Uptake of glucose by skeletal muscle, adipose and other tissues
→ Glycogen synthesis in liver and skeletal muscle
→ uptake of fatty acids and amino acids

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18
Q

What does glucose inhibit?

A

→ release of glucose from the liver

→ fat and protein breakdown

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19
Q

What is the main effect of glucagon?

A

→ stimulates hepatic glucose production

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20
Q

What are the main effects of adrenaline?

A

→ Stimulates hepatic glucose production

→ Stimulates lipolysis - release of FA from adipose tissues

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21
Q

What are the main effects of cortisol?

A

→ Stimulates hepatic glucose production

→ Stimulates proteolysis - release of amino acid from body proteins

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22
Q

What is glycogenesis?

A

→ synthesis of glycogen from glucose

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23
Q

What are the main effects of growth hormone?

A

→ Stimulates hepatic glucose production

→ lipolysis

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24
Q

What is lipogenesis?

A

→ synthesis of FA from acetyl CoA

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25
Q

What is triglyceride synthesis?

A

→ Esterification of FA for storage as TG

26
Q

What are the three metabolic pathways serving energy storage?

A

→ Glycogenesis
→ Lipogenesis
→ Triglyceride synthesis

27
Q

What are the 5 metabolic pathways serving energy release?

A 
→ Glycogenolysis
→ Gluconeogenesis
→ Lipolysis
→ Beta oxidation
→ Keto genesis
28
Q

What is ketogenesis?

A

→ Production of ketone bodies from acetyl CoA

29
Q

Why are ketone bodies useful to the brain?

A

→ They serve as a partial substitute for glucose

→ The brain can metabolize ketone bodies

30
Q

What happens in the pancreas if the plasma glucose concentration decreases?

A

→ Drop is sensed by secretory cells in pancreas
→ decrease insulin secretion
→ Increase glucagon secretion

31
Q

Where is hypoglycaemia sensed and what is done?

A 
→ Sensed in brainstem
→ Sympathetic response
→ Stimulation of adrenal glands
→ Release adrenaline
→ direct stimulation of pancreas
→ Direct stimulation of the liver to produce glucose
32
Q

What are 3 short term defences against hypoglycaemia?

A

→ Glucagon
→ Adrenaline
→ Sympathetic NS

33
Q

What is a medium term defense against hypoglycaemia and how ?

A

→ Ketogenesis - fat reserves provide a partial substitute for glucose
→ Spares muscle tissue from destruction

34
Q

What is a long term defense against hypoglycaemia and how ?

A

→ Cortisol stimulates proteolysis to supply amino acid substrates for gluconeogenesis

35
Q

What is a defence against hyperglycaemia and how ?

A

→ Insulin stimulates glucose uptake by tissues

→ Inhibits hepatic glucose production

36
Q

What are the 2 types of diabetes?

A

→ Type 1 - insulin deficiency

→ Type 2- insulin insufficiency combined with insulin resistance

37
Q

What are the major insulin sensitive tissues?

A

→ Liver
→ Skeletal muscle
→ Adipose tissue

38
Q

Where does glucose go if it is in excess?

A

→ Lipogenesis

39
Q

What do chylomicrons and VLDLs transport?

A

Transport TGs in the blood

40
Q

What do fatty acids get packaged into when they are absorbed from food?

A

→ FFA taken up and packaged into chylomicrons from food

41
Q

What is the main metabolic pathway in adipose tissue?

A

1) chylomicrons get changed into FFA by LPL
2) FFA re esterified stimulated by insulin for storage
3) glucose in circulation taken up stimulated by insulin
by GLUT 4 (when there is excess)
4)lipogenesis occurs
5) Adrenaline makes triglycerides break down and exported to circulation for use in energy metabolism

42
Q

What are newly synthesized fatty acids packaged into from the liver?

A

→ new fatty acids synthesized by the liver -lipogenesis

→ get packaged into VLDLs

43
Q

What is needed for uptake of fat into tissues for metabolism or storage?

A

→LPL

→to get TG into the cell from chylomicrons you need LPL to turn it back into TG

44
Q

Describe the major metabolic pathway in muscle

A

1) Insulin stimulates glucose uptake into muscle GLUT 4
2) used in TCA cycle
3) in excess it is stored as glycogen

45
Q

Describe the metabolic pathway of glucose and amino acid metabolism in the liver

A

1) Gluconeogenesis is stimulated by glucagon and inhibited by insulin
2) in the presence of glucagon amino acids enter gluconeogenesis or ketogenesis

46
Q

In the presence of insulin what happens to acetyl CoA?

A

→ lipogenesis

47
Q

In the presence of insulin what happens to the glucose in the liver?

A

→ lipogenesis

→produces malonyl CoA which is an intermediate

48
Q

In the absence of insulin what happens to the glucose in the liver?

A

→ beta oxidation stimulated by glucagon

49
Q

What can happen to the fatty acids entering the liver?

A

→ Esterified for transport and storage as TG

→ enter mitochondria for beta oxidation

50
Q

What does beta oxidation of FA produce?

A

→ Acetyl CoA

51
Q

What can acetyl CoA do?

A

→ enter TCA cycle

→ Ketogenesis

52
Q

What does an excess of ketone bodies in the blood do?

A

→ overwhelms the buffering capacity

→ Leads to metabolic acidosis

53
Q

What happens in diabetic ketoacidosis?

A

→ Decreased serum bicarbonate

→ Deep sighing

54
Q

What does an absence of insulin result in?

A

→gluconeogenesis and beta oxidation are running unopposed
→Beta-oxidation of FA produces acetyl Co A, →combines with oxaloacetate (OAA) to form citrate, entering the TCA cycle for complete oxidative phosphorylation
→OAA is also used as a substrate in gluconeogenesis
→In absence of sufficient OAA, acetyl Co A builds up and is funnelled into ketogenesis

55
Q

What is the role of insulin and glucagon in FA metabolism?

A

partition FA metabolism between lipogenesis and TG synthesis

Stimulation of lipogenesis (insulin) prevents FA entry to mitochondria, inhibiting beta oxidation

56
Q

What does insulin indirectly inhibit?

A

inhibits B-oxidation

57
Q

What are the two ways to increase GLUT4 density in muscle cell membrane?

A

(1) presence of insulin
(2) the process of muscle contraction

during exercise insulin levels normally decrease, but the contraction induced increase in GLUT4 allows continued glucose uptake

58
Q

What is the enzyme that allows VLDL/TAG to enter adipose tissue?

A

lipoprotein lipase stimulated by insulin

59
Q

Which is the most important buffer in rise of plasma glucose?

A

Skeletal muscle (large mass)

60
Q

Which is most important for controlling plasma glucose during fasting phase?

A

liver

61
Q

What type of cells in the pancreas produce beta cells?

A

alpha islet of Langerhans

62
Q

What are the glucose sparing mechanisms?

A

Lipolysis
Beta-oxidation
Ketogenesis

P1: Endo (12 decks)

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