Flashcard Set Preview
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| 1 |
What type of hormone is Growth Hormone?
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Polypeptide.
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| 2 |
Describe its biochemical properties.
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- 191 AAs (22 kDA)- 2 x disulphide bridges- Released from Somatotrophs (50% cell mass)
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| 3 |
Which cells release GH and where are they found?
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- Somatotrophs- Makes up 50% of adenohypophyseal tissue (anterior pituitary)
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| 4 |
How much GH is produced by an adult? How is this different in a developing adolescent?
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- 400 micrograms- Twice as much in developing adolescent-
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| 5 |
Describe the release of GH from the anterior pituitary.
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GHRH from hypothalamus (which nuclei?)Hypophyseal portal systemBinds to GH receptors on somatotrophscAMP...
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| 6 |
What other molecule causes release of GH and how does it act? Where is it produced?
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- Grehlin- Binds to separate receptor (IP3 mechanism leading to [Ca2+]i to be increased...
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| 7 |
What other important factor is released in parallel with GH levels?
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IGF-1 (Somatomedins)**NB - IGF-2 also released in smaller concentrations and is less important.
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| 8 |
Which tissues produce IGF-1 and which are most important?
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- Liver- Muscle- Bone(Bone and Muscle most important)
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| 9 |
How is GH release regulated?
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- Negative feedback (from both GH and IGFs)- Somatostatin is inhibitory and is triggered...
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| 10 |
GH is subject to a diurnal rhythm, what is this?
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- Cycle of release- 2-3hrs lasting and is released 5-8 pulses/day- Biggest release is shortly...
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| 11 |
Which factors stimulate GROWTH HORMONE release?
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- Hypoglycaemia- Stage II and III sleep- Exercise- Stress- Alpha-adrenoceptor agonists (clonidine)-...
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| 12 |
Which factors inhibit GROWTH HORMONE release?
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- Hyperglycaemia- Increased FFA consumption- Pregnancy- Beta-adrenoceptor agonists- Somatostatin-...
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| 13 |
What are the main effects of Growth Hormone?
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Diabetogenic- Increased hepatic gluconeogensis- Increased lipolysis- Increased glycogenolysisMuscle-...
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| 14 |
What are the effects of IGF-1?
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IGF-1 is structurally similar to and mimics insulin. It is so structurally similar that it...
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| 15 |
What are the signs of acromegaly?
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- Prominent jaw and facial features- Gaps between teeth- Coarsening of facial features (nasal...
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| 16 |
What are the other symptoms of acromegaly?
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- Osteoarthritis- Sweating- Weight gain- Diabetes
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| 17 |
What causes acromegaly most commonly?
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Pituitary tumor affecting somatotrophs
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| 18 |
What is the key difference between acromegaly and gigantism?
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gigantism is over-activity of growth hormone before the growth plates fuse. Growing does not...
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| 19 |
Describe some types of dwarfism:
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- Laron dwarfism = mutation in GH receptors- Achondroplastic dwarfism = muitation in FGR3 receptor,...
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| 20 |
How can you test the activity of growth hormone?
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- Glucose supression test- Stimulates GH release (or SHOULD in health individual!)
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