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SMP - MNE Exam 1 > Lecture 3: Growth Hormone and Acromegaly > Flashcards

Lecture 3: Growth Hormone and Acromegaly Flashcards

1
Q

What kind of molecules are GHRH and GH?

A

Peptides

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2
Q

<p>What is the ubiquitous role of somatostatin?</p>

A

<p>It inhibits cellular proliferation and activity</p>

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3
Q

<p>Describe the GH peptide.</p>

A

<p>191 AAs with 2 disulfide bonds</p>

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4
Q

<p>What hormone has a similar structure to GH? What is the small difference?</p>

A

<p>PRL

| 3 disulfide bridges instead of 2`</p>

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5
Q

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

A

<p>Bovine GH can bind both GH and PRL receptors so it's administered to cows to increase their size and milk production</p>

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6
Q

<p>Draw the feedback loops involved with GH production by pit. </p>

A

<p>INSERT IMAGE HERE</p>

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7
Q

<p>What is the major organ destination for GH?</p>

A

<p>The liver</p>

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8
Q

<p>What hormone does the liver produce upon receiving GH? 2 names</p>

A

<p>Somatomedin C = Insulin-Like Growth Factor-1 (IGF-1)</p>

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9
Q

<p>What kind of feedback is triggered by IGF-1 production by the liver?</p>

A

<p>3 long feedback loops:
- GH to ant pit
\+ SS to hypo
-GHRH to hypo </p>

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10
Q

<p>How does GH production by ant pit affect hypo?</p>

A

<p>Short loop:
\+ SS
- GHRH</p>

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11
Q

<p>What are the main 3 cellular processes stimulated by GH?</p>

A

<p>1. Growth

2. Cell reproduction
3. Cell regeneration</p>

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12
Q

<p>Is GH a metabolic or anabolic hormone?</p>

A

<p>Anabolic</p>

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13
Q

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

A 
<p>1. + protein synthesis
2. + RNA synthesis
3. + DNA synthesis
4. + cell size/function
= Increase size/function</p>
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14
Q

<p>7 effects of IGF-1 on chondrocytes? Overall effect?</p>

A 
<p>1. + AA uptake
2. + protein synthesis
3. + RNA synthesis
4. + DNA synthesis
5. + collagen
6. + chondroitin sulfate
7. + cell size/number
= LINEAR GROWTH when growth plates are open</p>
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15
Q

<p>What are chondrocytes?</p>

A

<p>Bone cells</p>

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16
Q

<p>3 effects of GH on adipose tissue? Overall effect?</p>

A

<p>+ lipolysis
- glucose uptake
\+ glycolysis
= DECREASED ADIPOSITY</p>

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17
Q

<p>4 effects of GH on liver tissue?</p>

A

<p>1. + RNA synthesis

2. + protein synthesis
3. + gluconeogenesis
4. + IGF-1</p>

18
Q

<p>3 effects of GH on nonactive muscles? Overall effect?</p>

A

<p>1. - glucose uptake
2. + AA uptake
3. + protein synthesis
= LEAN BODY MASS</p>

19
Q

<p>How do GNRH and SS affect each other?</p>

A

<p>They both inhibit each other's production</p>

20
Q

What are the 8 factors that stimulate GH secretion?

A
  1. Glucose decrease
  2. FA decrease
  3. AA increase (especially Arg)
  4. Fasting
  5. Stage 4 sleep (1 hour after sleep onset)
  6. Exercise
  7. Actute stress
  8. Sex hormones
  9. Alpha-adrenergic agonists
21
Q

What are the 8 factors that inhibit GH secretion?

A
  1. Glucose increase
  2. FA increase
  3. Cortisol = chronic stress
  4. Obesity
  5. Pregnancy
  6. SS
  7. GH
  8. IGF-1
22
Q

<p>Why is GH said to be a hyperglycemic hormone?</p>

A

<p>Because it raises glucose levels through gluconeogenesis and decrease glucose uptake by adipose tissue and muscle </p>

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

<p>How often does GH secretion happen during a normal 24h day?</p>

A

<p>Every 4 hours </p>

25
Q

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

A

<p>GH is low at birth, increases during childhood, peaks at puberty, and continues to decrease during adult life and senescence
SAME AS SEX HORMONES</p>

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 GH

Symptom: 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

<p>How does low LH affect testosterone levels? What does this cause?</p>

A

<p>Low testosterone levels causing decrease in libido and body hair AND decrease in hematocrit</p>

32
Q

<p>Why would administering fluids to a patient with macroadenoma worsen his condition?</p>

A

<p>Because the added fluid in the sella turcica will increase pressure </p>

33
Q

<p>What are the post-op treatments of hypophysectomy of macroadenoma?</p>

A

<p>End-organ hormone replacement therapy</p>

34
Q

<p>Why could macroadenoma cause increase in PRL?</p>

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

<p>Are pit tumors usually cancerous/metastatic?</p>

A

<p>NOPE</p>

36
Q

<p>Which predominates on GH production: GHRH or SS? </p>

A

<p>GHRH: net increase</p>

37
Q

<p>When can GH bind to PRL receptors?</p>

A

<p>When GH is in excess</p>

38
Q

<p>How does testosterone affect GH production? Why?</p>

A

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

39
Q

<p>How does estrogen affect GH production? </p>

A

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

40
Q

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

A

Via IV

SMP - MNE Exam 1 (25 decks)

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