Hormones in Development

Question 1

The baby’s main source of hormones is from the mother T/F?

Answer 1

FALSE - not normally through the placenta

Question 2

2 Examples of altered placenta metabolism

Answer 2

drugs

disease e.g. diabetes

Question 3

What 4 hormones can influence foetal development?

Answer 3

insulin
GH -> IGF’s
thyroid hormones
glucocorticoids

Question 4

What are the effects of Insulin, GH, and IGF in the foetus?

Answer 4

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

Question 5

How many IGFs involved and what do they do?

Answer 5

IGF-II - regulates early embryonic development

IGF-1 - growth of the newborn

Question 6

What does foetal thyroid hormones and glucocorticoids do?

Answer 6

TH - brain development and other growth

glucocorticoids - tissue differentiation and development of organs - lungs, liver, intestines

Question 7

In utero, which IGF is more important?

Answer 7

IGF-II is much more abundant

Question 8

What are the 3 broad activities of the IGFs?

Answer 8

metabolic
mitogenic
differentiative

Question 9

In more detail what do the IGF genes do?

Answer 9

IGF-II
drive for intrauterine growth 
IGF-I
regulates growth in relation to nutrient supply
IGF
uptake and ultilisation of nutrients

Question 10

How can levels of IGF be reduced in the foetus?

Answer 10

under-nutrition and deficiency of nutritionally sensitive hormones such as insulin, thyroxine and glucocorticoids

Question 11

What can amplify the effects of the IGFs?

Answer 11

IGF-binding proteins

Question 12

IGF-1 acts as a ‘regulatory signal’ – expressed in the presence of undernutrition. T/F?

Answer 12

TRUE

Question 13

IGF-II plays a key role in placental growth and nutrient transfer. T/F?

Answer 13

TRUE

Question 14

Which IGF is unaffected by gestational age and undernutrition?

Answer 14

maternal IGF-II

Question 15

At what day of pregnancy is fetal IGF-2 highest?

Answer 15

day 55

Question 16

Hypothyroidism in mother -> foetal disease. T/F?

Answer 16

TRUE

Question 17

Which gene is directly responsive to foetal thyroid hormone?

Answer 17

myelin basic protein gene

for fetal brain development

Question 18

Explain the chain of events leading to the increased levels of thyroid hormones in pregnant women by TBG

Answer 18

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

Question 19

How does iodine intake recommendations change in pregnancy?

Answer 19

increase iodine intake

Question 20

By what week does demand for thyroid hormones increase?

Answer 20

20 weeks till term

Question 21

Explain thyroid stimulation by hCG

In what population may this be a problem?

Answer 21

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.

Question 22

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?

Answer 22

• 12 weeks
• TRUE
• own thyroid and mother’s thyroid

Question 23

What are some effects of isolated maternal hypothyroidism on the mother and foetus?

Answer 23

usually associated with infertility

when pregnancy does occur, there is a risk of intrauterine fetal death and gestational hypertension

Question 24

What is cretinism? What is the effect of isolated foetal hypothyroidism? How do we prevent it?

Answer 24

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

Question 25

What’s the effect of iodine deficiency?

Answer 25

combined maternal and fetal hypothyroidism - causes mental retardation

Question 26

What is hyperthyroidism often associated with in terms of pregnancy?

Answer 26

pre-eclampsia
premature labour
fetal or perinatal death
low birth weight

Question 27

Thyroid hormones unaffected by undernutrition – T/F?

Answer 27

TRUE

Question 28

What organ systems affected by the adrenal hormones?

Answer 28

placental oestrogen, ovary, brain and maturation of the lungs

Question 29

When is intestinal maturation most glucocorticoid-sensitive?

Answer 29

late fetal and early neonatal period

Question 30

Explain relationship of cortisol with: undernutrition, gestational age, IGF-1,

Answer 30

undernutrition - elevated
gestational - increased
IGF-1 - inversely correlated

Question 31

In what time period does sexual differentiation occur?

Answer 31

3rd-12th week

Question 32

In males, at what week do the XXX cells secrete testosterone. What happens at week 7?

Answer 32

Leydig cells at week 6

7th week- anti-Müllerian hormone (AMH) is secreted by Sertoli cells, induces the atrophy of the paramesonephric ducts (Müller).

Question 33

In what conditions do the female gonads develop?

Answer 33

when the male differentiation conditions are absent