Somatic Growth Flashcards
What factors affect fetal growth?
Maternal genome
Maternal diet and metabolism
Uterine blood flow
Maternal environment
Adequate invation of the endometrium by the trophoblast
Placental hormone production
What hormones are important in regulating fetal growth?
IGF-1 and IGF-2
Insulin
Glucocorticoids
What are the two periods of rapid postnatal growth?
Birth-2 years
Puberty
What factors influence normal postnatal growth?
Genetic Factors
Adequate nutrition
Hormonal influences
What is the most important hormone in promoting postnatal growth?
Growth hormone, mediated by IGF-1
What is the effect of thyroid hormone on postnatal growth?
Required for normal linear growth
However, will not promote growth in the absence of GH
Thought to promote linear growth by increasing GH secretion
Growth rate increases in hyperthyroid children
What are the effects of sex steroids on growth?
Reason for the growth spurt at puberty
Stimulates GH secretion
What is the effect of estradiol on growth?
Stimulates growth plate maturation and fusion in both males and females
What is the role of androgens on growth?
Promote increased muscle mass in males
Thought to increase thickness of cortical bone
What is the effect of insulin on growth?
Promotes protein anabolism and inhibits protein catabolism
May have a permissive effect on GH-induced IGF-1 synthesis
What is the effect of glucocorticoids on growth?
Required for growth and overall health
Excessive amounts tend to interfere with growth
When the excess is removed, there is a period of catch-up growth
What is the cause GH deficiency originating from the hypothalmus?
GHRH deficiency
What is the cause of GH deficiency originating from the pituitary?
Somatotrope destruction by tumor
Production of a defective GH molecule
Decreased GH production
What is the cause of GH deficiency originating from target tissue?
GH receptor deficiency
Inability to produce IGF-1
What is Laron Dwarfism?
Caused by deletions or mutations in the gene for the GH receptor
Patients do not produce IGF in response to GH stimulation
High GH levels
