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Flashcards in Endocrine: Growth Deck (48)
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1
Q

Describe the pattern of GH secretion through the life cycle…

A

incraease post-natal, plateau in childhood, peak in puberty, plateau in adulthood, decline in senescence

2
Q

During puberty, what is increased in parallel to GH secretion?

A

IGF-1

3
Q

GH is released in what fashion, making it a bad indicator of pituitary somatotroph function?

A

pulsatile variation throughout day

4
Q

What 3 things broadly increased GH release?

A

Exercise, fasting, sleep

5
Q

______ is the primary stimulator of GH secretion, while ______ is the primary inhibitor

A

Stimulator: GHRH
Inhibitor: Somatostatin (GHIH)

6
Q

This enzyme regulates genes involved in growth and development, such as GH and GH Receptors.

It is stimulated by GHRH binding to Gs, and inhibited when somatostatin binds Gi.

A

PIT1 via CREB (Adenylyl cyclase, PKApathway)

7
Q

What exerts negative feedback on the hypothalamus and pituitary to curb release of GHRH and increase somatostatin release?

A

GH, IGF-1

8
Q

GH can induce the following growth actions indirectly via which action?

  • ↑ protein synth
  • ↑ Cell division
  • ↑ Bone growth
A

IGF-1

9
Q

GH has the following effects via direct or indirect action?

↑ blood glucose from liver

↑ lipolysis (blood FAs)

↓ Glucose uptake in muscle

A

Directly

10
Q

GH has Anabolic or Catabolic on the below?

Muscle protein

AA

Fatty Acids

A

Muscle protein, amino acids: Anabolic

Fat: catabolic

11
Q

In the fed state, protein supply is high with a mixed meal. What are the effects on GH, IGF and Insulin concentration? What happens as a result?

A

Increased GH, IGF, Insulin

Protein anabolism and growth

12
Q

GH facilitates _____ to promote growth…

A

insulin

13
Q

In the fed state with high CHO consumption, What happens to GH, IGF-1, and Insulin? What occurs as a result?

A

Decreased GH, NC IGF, Increased insulin

increased caloric storage

14
Q

_____ suppresses GH release while increasing insulin in order to promote CHO storage…

A

hyperglycemia suppresses GH release

15
Q

Describe the effect fasting has on GH, IGF and Insulin concentrations. What happens as a result?

A

Increased GH

Decreased IGF 1, insulin

Decreased anabolism and growth, increased caloric mobilization

16
Q

Why does GH rise in the fasting state?

A

hypoglycemia stimulates GH secretion

17
Q

In the fasting state, you have increased GH and Cortisol. This promotes synthesis of _____, which has what effect?

A

increased IGF-BP, limits IGF-1 availability to curb growth

18
Q

Long bone growth will be stimulated by GH/IGF-1 as long as ____

A

growth plate stays open

19
Q

Pubertal growth correlates with plasma level of…

A

IGF-1

20
Q

This is a condition of excessive linear growth by increased stimulation of epiphyseal plates in the presence of GH excess.

A

gigantism

21
Q

This is a condition where GH effects take place absent of linear bone growth, S/S include:

Gradual onset

deformity, large hands/feet

DM risk

viscera increase

Increased protein, decreased body fat

A

Acromegaly

22
Q

What is responsible for 98 % of acromegaly, how is this detected?

A

somatotrope adenoma, detected via pituitary MRI

23
Q

What two non-imaging diagnostics can help dx acromegaly?

A

Increased serum IGF-1

OGTT > 1 ng/ml

24
Q

What are 5 etiologies of dwarfism during growth?

A

↓ GHRH, ↓ IGF-1 (pygmies), ↓ IGF-BP

Pituitary insufficiency

No response to GH (laron dwarfs)

25
Q

Can growth occur absent thyroid hormone, but adequate GH? Why?

A

no, T3/T4 permit GH release

26
Q

Cretinism occurs from inadequate _____

A

thyroid hormone

27
Q

This hormone:

  • ↑ bone turnover
  • ↑ activity of chondrocytes and ↑osteoblast proliferation
  • ↑ osteoclast action
  • ↑ IL6, PGE2, IGF1 Receptors in bone (growth factors)
A

Thyroid Hormones

28
Q

Prolactin secretion and mammary development relies on …

A

T3/T4

29
Q

The following have what effect on GHRH release from the hypothalamus?

  • Sex steroids
  • Ghrelin
  • Alpha-2 receptors
A

↑ GHRH

30
Q

The following have what effect on GH secretion from the anterior pituitary?

  • Glucocorticoids
  • Thyroid hormones
  • Ghrelin
A

↑ GH release

31
Q

The following have what effect on somatostatin release from the hypothalamus?

  • GC
  • Glucose
  • FFAs
  • Beta 2 activation
A

↑ Somatostatin

32
Q

The following have what effect on somatostatin release from the hypothalamus?

Ghrelin
Arginine
DA
Serotonin
ACh
A

Inhibit somatostatin

33
Q

3 positive effects of glucocorticoids on GH signaling?

A

↑ GH gene expression, ↑ GHRH receptors, ↑ Ghrelin receptors

34
Q

2 negative effects of excess glucocorticoids…

A

↑ somatostatin

↓ peripheral GH receptors

35
Q

Cushings and Exogenous glucocorticoids can have what effect on growth?

A

muted GH secretion, suppressed growth

36
Q

Adrenalectomy would have what two effects in the pituitary?

A

↓ GHRH and Ghrelin receptors

37
Q

ACTH deficiency and hypocorticsolism are associated with…

A

↓ GH

38
Q

Both low and high GC concentration have what effect on GH secretion?

A

↓ GH

39
Q

Testosterone and GH have what synergistic effect in the liver?

A

↑ IGF-1 secretion

40
Q

Estrogen has what effect in the liver?

A

↓ IGF-1 secretion

41
Q

Muscle growth is a function of what three factors?

A

conditioning, nutrition, hormone signaling

42
Q

Muscle strength increases rapidly with training.Results can occur how quickly?

A

hours to days

43
Q

T/F?

Exercise increases glucose entry into cells absent of insulin

A

T

44
Q

Infusion of ____ can stimulate muscle growth independent of training in the vastus lateralis and soleus…

A

amino acids

45
Q

The below have what effect on mTOR

  • Insulin
  • IGF-1
  • Amino Acids
  • Phosphatidic Acid
A

Stimulate

46
Q

The below have what effect on mTOR

  • fasting
  • low protein
  • AMPK
  • Myostatin
  • GC
  • Cytokines
A

Inhibit

47
Q

mTOR has what effect on muscle growth?

A

increase muscle protein synthesis

48
Q

This is a developmental gene that blocks muscle cell growth and differentiation.

It inhibits insulin action

A

myostatin