Endocrinology Flashcards
1) What is the precursor for Estriol?
DHEAS. The placenta lacks 17-alpha-hydroxylase, which is required for the synthesis of estrogens from cholesterol. Therefore, the fetal adrenal cortex synthesizes DHEAS from cholesterol (derived from maternal LDL), which surves as the precursor for placental estrogen synthesis. Of note, the fetal adrenal lacks 3-beta-hydroxylase, which is necessary for the synthesis of cortisol.
Enzyme placenta lacks
he placenta lacks 17-alpha-hydroxylase
Enzyme fetal adrenal lacks
Of note, the fetal adrenal lacks 3-beta-hydroxylase, which is necessary for the synthesis of cortisol.
2) What is the precursor for fetal steroid synthesis?
The fetus & placenta obtain cholesterol from maternal LDL in order to proceed with steroidogenesis.
3) What is LH critical for?
a) External genitalia
b) Pituitary
External genitalia. LH stimulates the testes to produce testosterone.
4) What is an obligate precursor for NO? What is the enzyme?
NO is a product of the conversion of L-arginine to L-citrulline, catalyzed by nitric oxide synthase.
5) Which is the largest phospholipid?
a) Phosphotidylinositol
b) Phosphatidylglycerol
c) Phosphatidylcholine
C. Phosphatidylcholine comprises >70% of surfactant.
HPL is like what two hormones in the mother?
hPL is homologous to prolactin & growth hormone. It is synthesized in cytotrophoblasts by 6 weeks. hPL is synthesized at a rate of 1/g day – the greatest amount of hormone synthesis in humans.
7) Which is least/most associated with adrenal insufficiency?
a) Increased Na
b) Hypotension
c) Increased glucose
A ) Adrenal insufficiency is characterized by a lack of cortisol & lack of mineralocorticoids. The presenting symptoms (acute) are hypotension, hyponatremia, hypoglycemia, & hyperkalemia.
8) Homolog to HPL?
a) LH/FSH
b) glucagon/ somatostatin
c) HGH/prolactin
C
11) Which substance is missing in the placenta but present in the fetal adrenal gland?
a) Glucose
b) Progesterone
c) 17-OH dehydrogenase
C. 17-alpha-hydroxylase is absent from the placenta but found in the fetal adrenal gland. Consequently, the fetal adrenal gland synthesizes DHEAS from cholesterol, and DHEAS serves as precursor to estrogen synthesis in placenta.
12) TRH is a
a) Polypeptide
b) Protein
A tripepetide hormone
13) All of the following are associated with maternal hyperparathyroidism except:
a) Fetal intracranial calcifications
b) Fetal hypocalcemia
c) Neonatal tetany
A. Intracranial calcifications.
Maternal hyperparathyroidism → maternal hypercalcemia → active transport of calcium across placenta → fetal hypercalcemia → ↓ fetal PTH→ delivery cuts fetus off from calcium supply → neonatal hypocalcemia → tetany.
