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G2 2017-2018 > Physiology - Growth Hormone and Acromegaly > Flashcards

Physiology - Growth Hormone and Acromegaly Flashcards

1
Q

What kind of molecules are GHRH and GH?

A

Peptides

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2
Q

What is the ubiquitous role of somatostatin?

A

It inhibits cellular proliferation and activity

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3
Q

Describe the GH peptide.

A

191 AAs with 2 disulfide bonds

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4
Q

What hormone has a similar structure to GH? What is the small difference?

A

PRL3 disulfide bridges instead of 2`

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5
Q

How is the similar structure of PRL and GH put to use in real life?

A

Bovine GH can bind both GH and PRL receptors so it’s administered to cows to increase their size and milk production

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6
Q

Draw the feedback loops involved with GH production by pit.

A

INSERT IMAGE HERE

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7
Q

What is the major organ destination for GH?

A

The liver

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8
Q

What hormone does the liver produce upon receiving GH? 2 names

A

Somatomedin C = Insulin-Like Growth Factor-1 (IGF-1)

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9
Q

What kind of feedback is triggered by IGF-1 production by the liver?

A

3 long feedback loops:- GH to ant pit+ SS to hypo-GHRH to hypo

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10
Q

How does GH production by ant pit affect hypo?

A

Short loop:+ SS- GHRH

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11
Q

What are the main 3 cellular processes stimulated by GH?

A
  1. Growth2. Cell reproduction3. Cell regeneration
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12
Q

Is GH a metabolic or anabolic hormone?

A

Anabolic

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13
Q

4 effects of IGF-1 on visceral tissue and organs (bones, heart, lungs, kidneys, pancreas, intestines, skin, connective tissues)? Overall effect?

A
    • protein synthesis2. + RNA synthesis3. + DNA synthesis4. + cell size/function= Increase size/function
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14
Q

7 effects of IGF-1 on chondrocytes? Overall effect?

A
    • AA uptake2. + protein synthesis3. + RNA synthesis4. + DNA synthesis5. + collagen6. + chondroitin sulfate7. + cell size/number= LINEAR GROWTH when growth plates are open
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15
Q

What are chondrocytes?

A

Bone cells

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16
Q

3 effects of GH on adipose tissue? Overall effect?

A

+ lipolysis- glucose uptake+ glycolysis = DECREASED ADIPOSITY

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17
Q

4 effects of GH on liver tissue?

A
    • RNA synthesis2. + protein synthesis3. + gluconeogenesis4. + IGF-1
18
Q

3 effects of GH on nonactive muscles? Overall effect?

A
    • glucose uptake2. + AA uptake3. + protein synthesis= LEAN BODY MASS
19
Q

How do GNRH and SS affect each other?

A

They both inhibit each other’s production

20
Q

What are the 8 factors that stimulate GH secretion?

A
  1. Glucose decrease2. FA decrease3. AA increase (especially Arg)4. Fasting5. Stage 4 sleep (1 hour after sleep onset)6. Exercise7. Actute stress8. Sex hormones 9. Alpha-adrenergic agonists
21
Q

What are the 8 factors that inhibit GH secretion?

A
  1. Glucose increase2. FA increase3. Cortisol = chronic stress4. Obesity5. Pregnancy6. SS7. GH 8. IGF-1
22
Q

Why is GH said to be a hyperglycemic hormone?

A

Because it raises glucose levels through gluconeogenesis and decrease glucose uptake by adipose tissue and muscle

23
Q

Why is GH inhibited by pregnancy?

A

Because placenta makes its own called HPL which has a short loop negative feedback on hypo: + SS and - GHRH

24
Q

How often does GH secretion happen during a normal 24h day?

A

Every 4 hours

25
Q

How does GH production vary during the life span? What hormones is this similar too?

A

GH is low at birth, increases during childhood, peaks at puberty, and continues to decrease during adult life and senescenceSAME AS SEX HORMONES

26
Q

What is acromegaly due to? To what patients?What are the symptoms?

A

Pit tumor (micro or macro) causing overproduction of GH in adults (middle age)Symptoms: overgrowth of soft tissues of face (nose and lips), hands, feet, and bones

27
Q

What is gigantism due to? What are the symptoms?

A

Macroadenoma causing overproduction of GH in children (before closure of epiphysial endplate in puberty)Symptoms: incredible height (7-8 feet), and sometimes acromegaly in adulthood

28
Q

What is pituitary dwarfism due to? What are the symptoms?

A

Inability of pit to produce enough GHSymptom: insufficient stature growth

29
Q

What is Laron dwarfism due to? What are the symptoms?

A

Special subset of pit dwarfism due to lack of functioning GH receptors Symptoms: insufficient stature growth and high GH because IGF-1 is not produced

30
Q

What is wide-range hypopituitarism?

A

When a patient has a dysfunction of many cell types contained in the anterior pit

31
Q

How does low LH affect testosterone levels? What does this cause?

A

Low testosterone levels causing decrease in libido and body hair AND decrease in hematocrit

32
Q

Why would administering fluids to a patient with macroadenoma worsen his condition?

A

Because the added fluid in the sella turcica will increase pressure

33
Q

What are the post-op treatments of hypophysectomy of macroadenoma?

A

End-organ hormone replacement therapy

34
Q

Why could macroadenoma cause increase in PRL?

A

If tumor is really pressing hard it is cutting flow of venous blood from the hypo to pit gland so dopamine is not making it to the pit

35
Q

Are pit tumors usually cancerous/metastatic?

A

NOPE

36
Q

Which predominates on GH production: GHRH or SS?

A

GHRH: net increase

37
Q

When can GH bind to PRL receptors?

A

When GH is in excess

38
Q

How does testosterone affect GH production? Why?

A

It substantially increases GHRH and SS so it causes episodic levels of GH (high peaks and very low baseline level)Causes maximal somatic growth

39
Q

How does estrogen affect GH production?

A

It moderatly increases GHRH and SS so it causes disorganized episodic levels of GH (lower peaks and higher baseline level than in males)

40
Q

How would a treatment of peptide hormones need to be administered?

A

Via IV

G2 2017-2018 (45 decks)

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