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PRINb 401 > WK7 - Endocrine Regulation of Metabolism > Flashcards

WK7 - Endocrine Regulation of Metabolism Flashcards

1
Q

What is glucose used for?
How is it stored?
What is it synthesized from?

A
  • used for ATP synthesis
  • stored as glycogen or triglyceride
  • synthesized from precursors (glycerol, lactate, amino acids)
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2
Q

What is fat used for?

How is it stored?

A
  • used for ATP synthesis (oxidative metabolism)

- stored as triglyceride (TAG)

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3
Q

What is amino acids used for?

A
  • used for glucose production (gluconeogenesis)

- used for the synthesis of protein

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4
Q

What hormones are responsible for regulation of fuel metabolism?

A
  • insulin
  • glucagon
  • epinephrine/norepinephrine
  • cortisol
  • growth hormone
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5
Q

The pancreas is divided functionally in 2 parts. What are they?

A
  1. Exocrine pancreas
    - digestive enzymes secreted into intestine
  2. Endocrine pancreas
    - hormones secreted into blood
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6
Q

How is the endocrine pancreas organized?

A
  • clusters of cells called Islets (~1000-5000 cells/islet)
  • comprise 1-3% of the adult pancreas and contain multiple cell types
  • beta-cell comprise 60-80% of the islet
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7
Q

What are the cell types of the pancreatic islet?

A

alpha cells - glucagon

beta cells - insulin

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8
Q

What is the site of production of insulin?

A
  • produced by beta-cells of the pancreatic islet
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9
Q

What type of hormone is insulin?

A

peptide hormone - encoded by the insulin gene

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10
Q

What stimulates the secretion of insulin?

A

Insulin are secreted in response to nutrients and hormones

  • secreted from pancreatic beta-cells in fed state
  • stimuli for secretion: glucose, amino acids, fatty acids, other hormones
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11
Q

What are the target tissues of insulin?

A

All cells express insulin receptors.

Insulin regulates metabolically active tissues:

  • liver
  • skeletal muscle
  • heart
  • adipose tissue
  • brain
  • pancreas
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12
Q

What happens in the absence of insulin?

A

Without insulin:

  • cells cannot take up and utilize glucose
  • fuels is mobilized not stored

Result:
- excess nutrients are circulate in the blood but they cannot be used as fuel source

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13
Q

Describe the effects of insulin on fuel metabolism.

A
  • The overall effect of insulin is to promote the utilization of glucose and the storage of surplus fuel in times of “feast” - Insulin is an ANABOLIC hormone
  • decrease lipolysis (in adipose tissue)
  • decrease gluconeogenesis (in hepatocyte)
  • decrease glycogenolysis (in liver and muscle)
  • increase glycogen synthesis (in liver and muscle)
  • increase glucose uptake/breakdown (in all tissues)
  • increase TAG synthesis and storage (in adipose tissue)
  • increase protein synthesis (in muscle)

Overall effect: promote the utilization of glucose and the storage of surplus fuel

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14
Q

What is seen in untreated diabetes?

A
  • high blood glucose levels
  • increase fatty acids in blood because unable to store triclycerides; therefore increase in triglyceride levels

Recall: excess nutrients circulate in blood but cannot be used as fuel source

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15
Q

Which hormones allow us to use stored energy reserves and mobilize fuel in times of fasting or “famine”?

A

Fast:

  • glucagon
  • epinephrine/norepinephrine

Slow:

  • cortisol
  • growth hormone
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16
Q

What is the site of production of glucagon?

A

alpha-cells of the pancreas

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17
Q

What type of hormone is glucagon?

A

peptide hormone - encoded by the glucagon gene

18
Q

What are the targets of glucagon?

A
  • liver

- adipose tissue

19
Q

What are the effects of glucagon?

A
  • increase gluconeogenesis (in hepatocyte
  • increase glycogenolysis (in liver and muscle)
  • increase lipolysis of TAG (in adipose tissue)
  • decrease glycogen synthesis (in liver and muscle)

Overall effect: mobilization of fuel

20
Q

What stimulates the release of glucagon?

A

released when blood glucose and insulin is low

21
Q

What is the site of production of epinephrine?

A

EPI - produced by cells of the adrenal medulla

22
Q

What type (or what is the derivative) of hormone is epinephrine?

A

Derivative of tyrosine

23
Q

What are the targets of epinephrine?

A

acts on liver, adipose tissue and skeletal muscle

24
Q

When is epinephrine released?

A
  • for ‘fight or flight’ response

- released when blood glucose levels are low

25
Q

What are the effects of epinephrine?

A
  • increase of gluconeogenesis (in liver)
  • increase glycogenolysis (in muscle and liver)
  • increase lipolysis (in fat)
  • increase glucagon secretion (from pancreas)
  • decrease insulin secretion (from pancreas)

Overall effect: Mobilization of fuel

26
Q

What is the site of production of cortisol?

A

produced by the adrenal cortex

27
Q

What type (and what is the derivative) of hormone is cortisol?

A

steroid hormone - derivative of cholesterol

  • also a stress hormone
28
Q

When is cortisol released?

A

released during a prolonged fast

29
Q

What are the effects of cortisol?

A
  • increase glucose production
  • increase lipolysis
  • decrease glucose utilization

Overall effect: Mobilization of fuel

30
Q

What is the site of production of growth hormone?

A

produced and secreted from somatotrophes of the anterior pituitary

31
Q

What type (and what is the derivative) of hormone is growth hormone?

A

peptide hormone - encoded by the growth hormone gene

32
Q

When is growth hormone released?

A

released during a prolonged fast

33
Q

What are the effects of growth hormone?

A
  • increase glucose production
  • increase protein synthesis (growth)
  • decrease glucose utilization

Overall effect: raise blood glucose levels, promote protein synthesis

34
Q

What are the complications of poorly managed or untreated diabetes?

A

Long-term: high blood glucose causes tissue damage (nerve cells and blood vessels)

Diabetic complications: peripheral neuropathy, retinopathy, kidney failure, heart disease, etc.

Severe-acute: diabetic ketoacidosis

35
Q

What is the role of leptin?

A

act as a chemical messenger that allows the brain to receive information about short- and long term nutritional status from gut- and fat- derived hormones

36
Q

What happens in a child when there is a leptin gene mutation?

A
  • morbidly obese
  • in a chronic state of positive energy balance
  • hyperphagia - increased appetite
  • decreased energy expenditure
37
Q

What is fat’s job in fuel metabolism?

A

Storage depot: stores excess energy as triglyceride

Endocrine organ : synthesizes and secretes hormones (ie. leptin)

38
Q

Where are leptin produced?

A

produced and secreted by fat cells - circulating levels of leptin are proportional to the amount of adipose tissue

39
Q

What are the effects of leptin?

A
  • decrease food intake

- increase energy expenditure

40
Q

What are the factors with obesity?

A
  • physiological regulation of body weight
  • environmental factors
  • susceptibility to disease is inherited (other chronic diseases such as dyslipidemia, diabetes, CVD, alcoholism)

PRINb 401 (3 decks)

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