Hormones in Development Flashcards
The baby’s main source of hormones is from the mother T/F?
FALSE - not normally through the placenta
2 Examples of altered placenta metabolism
drugs
disease e.g. diabetes
What 4 hormones can influence foetal development?
insulin
GH -> IGF’s
thyroid hormones
glucocorticoids
What are the effects of Insulin, GH, and IGF in the foetus?
insulin - indirect on growth, direct on adipose tissue and proliferation and differentiation and prenatal maturation
GH - no direct effect but have an affect on insulin-like growth factors (IGF) - fetal met
How many IGFs involved and what do they do?
IGF-II - regulates early embryonic development
IGF-1 - growth of the newborn
What does foetal thyroid hormones and glucocorticoids do?
TH - brain development and other growth
glucocorticoids - tissue differentiation and development of organs - lungs, liver, intestines
In utero, which IGF is more important?
IGF-II is much more abundant
What are the 3 broad activities of the IGFs?
metabolic
mitogenic
differentiative
In more detail what do the IGF genes do?
IGF-II drive for intrauterine growth IGF-I regulates growth in relation to nutrient supply IGF uptake and ultilisation of nutrients
How can levels of IGF be reduced in the foetus?
under-nutrition and deficiency of nutritionally sensitive hormones such as insulin, thyroxine and glucocorticoids
What can amplify the effects of the IGFs?
IGF-binding proteins
IGF-1 acts as a ‘regulatory signal’ – expressed in the presence of undernutrition. T/F?
TRUE
IGF-II plays a key role in placental growth and nutrient transfer. T/F?
TRUE
Which IGF is unaffected by gestational age and undernutrition?
maternal IGF-II
At what day of pregnancy is fetal IGF-2 highest?
day 55
Hypothyroidism in mother -> foetal disease. T/F?
TRUE
Which gene is directly responsive to foetal thyroid hormone?
myelin basic protein gene
for fetal brain development
Explain the chain of events leading to the increased levels of thyroid hormones in pregnant women by TBG
increased [T4-binding globulin] stimulated by oestrogen
- > lower free [T4]: elevated TSH secretion by pituitary
- > increase in total T4 and T3: increased demand for thyroid hormones
- > increased demand for iodine: significant increased clearance
How does iodine intake recommendations change in pregnancy?
increase iodine intake
By what week does demand for thyroid hormones increase?
20 weeks till term
Explain thyroid stimulation by hCG
In what population may this be a problem?
hCG - chronic gonadotropin
placenta secretes huge amounts hCG, which is similar to TSH
hCG can use the TSH receptor on thyroid epithelial cells
blood levels of TSH often are suppressed
thyroid-stimulating activity of hCG actually causes some women to develop transient hyperthyroidism.
At what week can the foetus’ thyroid make thyroid hormones?
Placenta has deiodinase enzymes T/F?
What are the foetus’ source(s) of thyroid hormone?
- 12 weeks
- TRUE
- own thyroid and mother’s thyroid
What are some effects of isolated maternal hypothyroidism on the mother and foetus?
usually associated with infertility
when pregnancy does occur, there is a risk of intrauterine fetal death and gestational hypertension
What is cretinism? What is the effect of isolated foetal hypothyroidism? How do we prevent it?
congenital hypothyroidism due to failure of the fetal thyroid gland
- if not treated quickly, child will become mentally and growth retarded (cretinism = congenital deficiency of thyroid hormone)
screening
What’s the effect of iodine deficiency?
combined maternal and fetal hypothyroidism - causes mental retardation
What is hyperthyroidism often associated with in terms of pregnancy?
pre-eclampsia
premature labour
fetal or perinatal death
low birth weight
Thyroid hormones unaffected by undernutrition – T/F?
TRUE
What organ systems affected by the adrenal hormones?
placental oestrogen, ovary, brain and maturation of the lungs
When is intestinal maturation most glucocorticoid-sensitive?
late fetal and early neonatal period
Explain relationship of cortisol with: undernutrition, gestational age, IGF-1,
undernutrition - elevated
gestational - increased
IGF-1 - inversely correlated
In what time period does sexual differentiation occur?
3rd-12th week
In males, at what week do the XXX cells secrete testosterone. What happens at week 7?
Leydig cells at week 6
7th week- anti-Müllerian hormone (AMH) is secreted by Sertoli cells, induces the atrophy of the paramesonephric ducts (Müller).
In what conditions do the female gonads develop?
when the male differentiation conditions are absent
