Energy Balance Flashcards

1
Q

What are the key hormonal systems involved in humans/animals?

A
  • GH (insulin-like growth factor-1 = IGF-1 axis)
  • thyroid hormones
  • sex hormones
  • androgens
  • estrogens
  • insulin
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2
Q

What other hormones have powerful modifying effect?

A
  • cortisol
  • glucocorticoids
  • leptin
  • progesterone
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3
Q

What study models can be used to study growth?

A
  • deficiency syndromes (GH/iodine deficiency)
  • over-production tumours (pituitary tumours)
  • pharmacological stimulation
  • nutritional interactions (under/over-feeding studies)
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4
Q

What is leptin from adipose tissue’s effect on?

A

appetite and growth

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5
Q

When the body cannot produce leptin, what happens?

A

obese

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6
Q

What is myostatin?

A

negative regulator of skeletal muscle growth

- its deletion/inhibition causes extreme muscular development in animals/humans

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7
Q

Why is there a need for energy balance?

A

for net accretion of tissues to take place and growth to occur in muscle/lean/organ/adipose tissues and bone + fat mass

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8
Q

What are the body composition compartments?

A
  • body fat
  • skeletal muscle mass
  • organs
  • water
  • bones
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9
Q

What is body fat made up principally of?

A

adipose tissue made of lipids

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10
Q

What are organs and skeletal muscle made up of?

A

lean tissue made up of protein and water predominantly

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11
Q

What is bone tissue made up of?

A

minerals and some protein

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12
Q

What is protein turnover?

A

takes place everyday, continuous breakdown and renewal of protein

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13
Q

What must be so, for NET protein synthesis to occur?

A

synthesis MUST be greater than breakdown

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14
Q

Name the anabolic hormones having the positive effect on net protein synthesis in muscle:

A
  • GH-IGF
  • androgens
  • insulin
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15
Q

Name the catabolic hormones having the negative effect on net protein synthesis in muscle:

A
  • cortisol
  • glucocorticoids
  • proinflammatory cytokines
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16
Q

Name the hormones that have modulatory effects on growth and protein turnover:

A
  • catecholamines
  • thyroid hormone (major impact on fetal growth)
  • estrogens
  • progesterones
  • leptin
  • ghrelin
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17
Q

Name the particular amino acids that are essential for protein synthesis to occur:

A
  • essential aa

- branched chain aa (leucine)

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18
Q

When the catabolic state is created during infection and illness, what does it include?

A

heightened proinflammatory cytokine production and cortisol

19
Q

what hormone reductions are there during dietary restriction?

A

insulin, IGF-1, thyroid activities

20
Q

What is one generic description of how nutritional intake affects hormonal status in different ways?

A

nutrient-gene interactions

21
Q

What is the GH-IGF axis?

A
  • major system that regulates global growth and development of tissues (bone, tissues) esp. during childhood growth/development
  • both the GH and IGF-1 have major effects on tissue growth and development
  • highly regulated by nutrition and other hormones too (thyroid, sex hormones, leptin, insulin)
22
Q

Where is GH produced?

A

pituitary gland

23
Q

where is IGF-1 produced?

A

by liver under stimulation of GH

24
Q

Which has a greater anabolic impact on protein turnover, GH or IGF-1?

A

IGF-1

25
Q

Does GH have a substantial metabolic role?

A

Yes

26
Q

What is the local production of growth factors such as IGF-1/GH regulated by?

A

factors like hormones, nutrition and exercise

27
Q

When GH is produced, what does it affect?

A

hepatic and local production of IGF-1 (autocrine and paracrine)

28
Q

What are the effects of dietary restriction on GH-IGF axis?

A
  • along with stress, can increase GH release (to increase fat mobilisation, lipolysis)
  • downstream problem
  • loss of IGF production + activity
  • alteration in IGF binding proteins = affects clearance and cellular activity
29
Q

Meat is a bioavailable source of?

A

protein, essential amino acids and other nutrients

30
Q

What are critical factors in meat production?

A

feed efficiency and growth rates

31
Q

What are beta-adrenergic agonists?

A

bind selectively to beta adrenergic receptors in tissues

  • modelled on adrenaline/noradrenaline
  • sympathomimetic amines
32
Q

Give an example of beta-adrenergic agonists?

A

classical asthma drugs

salbutamol

33
Q

What are beta-agonists used usually in?

A

classically used in farm animal research studies and meat production

34
Q

What are some types of beta-agonists?

A
  • cimaterol
  • clenbuterol
  • ractopamine
35
Q

What is the beta 2 receptor’s effect on?

A

potent effect on fat loss in adipose tissue and protein gain in muscle

36
Q

What is the effect of BAA (beta-adrenergic factor) on fibre?

A

there’s switch in fibre type from slow to fast WITH chronic administration

37
Q

Explain the nutrient repartitioning concept:

A
  • drugs/BAA affect lipid and protein metabolism
  • energy is diverted from fat towards muscle
  • basically, decreased synthesis in adipose tissue (fatty acids, glycerol, triglycerides involved), but increase for skeletal muscle tissue (amino acids and proteins involved)
  • degradation for adipose increase but opposite for muscle tissue
38
Q

The effects of BAA administration are?

A
  • reducing adipose tissue mass, lipogenesis, protein breakdown, but
  • increase lipolysis, muscle mass, protein synthesis
39
Q

Explain the mechanism of ß-adrenergic receptor signal transduction:

A
  1. receptor activated by agonist and interacts with Gs proteins
  2. Gs proteins stimulate adenylyl cyclase to convert ATP to cAMP
  3. Increased cAMP activates protein kinase A (PKA) to phosphorylate enzymes + regulatory factors = metabolic regulation
40
Q

What is the usual duration period of BAA treatments?

A

desensitisation over 2 week period

41
Q

Explain the dosages of BAA treatments:

A
  • asthma drugs low dose

- higher dose = better gains

42
Q

Which muscle fibre types do BAA have specific effects on?

A
  • fast twitch fibres

- causes transition of fibre types

43
Q

What has BAA treatment been considered for?

A
  • muscle wasting (muscular dystrophy, cancer cachexia, AIDS)

- it antagonises DEX