Growth hormone signaling
This hormone is secreted as a downstream result of growth hormone signaling in the liver.
Insulin-like growth factor I (IGF-1)
How does GHD affect bone age?
Decreases it
What kind of receptor does IGF-1 bind?
Receptor tyrosine kinase
What causes psychosocial short stature?
Neglect and abuse
Where is somatostatin released from?
The hypothalamus
What hormone inhibits GH secretion?
Somatostatin
What is the pattern of growth hormone secretion during wake and sleep?
Pulsatile; with highest peaks during stages 3 and 4 of sleep
What happens to the IGF-1 receptor once IGF-1 binds to it?
It autophosphorylates itself
What behavior may accompany psychosocial short stature type IIA?
Hoarding, stealing, and overeating food
Why is the portal system important?
It prevents hypothalamic hormones from being diluted in the blood before reaching the pituitary
What two effects can growth hormone have on adipocytes?
Triglyceride breakdown (lipolysis) or ketogenesis
Why can GHD not be noticeable in children until they are older?
Nutrition and thyroid hormone are more important for growth in early months
How does IGF-1 affect cells?
It prevents apoptosis
Describe how short stature can affect social development in children
Being treated differently (infantilization) can cause insecurity, shyness, immaturity, and/or provocative behavior that hinders them socially
What is the difference in embryologic origin between the anterior and posterior pituitary?
Anterior pituitary originatse from the ectodermal layer
Posterior pituitray originates from the neuroectoderm
Briefly describe the JAK-STAT pathway in hepatocytes
GH binds tyrosine kinase like receptor --> conformational change --> cross-phosphorylation of JAKs --> JAK phosphorylates STAT --> STAT binds DNA to promote transcription
What components are necessary to make a diagnosis of growth hormone deficiency?
Clinical assessment/auxology, levels of IGF-1 and IGFBP-3, and GH stimulation tests
What adaptor proteins associate with IGF-1 receptor after it autophosphorylates?
Insulin receptor substrates (IRSs) and Shc
Which genetic cause of short stature is caused by a chromosome 15 abnormality?
Prader-Willi syndrome
What hormones are released by the arcuate nucleus (100pts each or 400 for all)?
Growth-hormone-releasing hormone, gonadotropin-releasing hormone, and dopamine