Lecture 12 - Endocrinology of Pregnancy and Parturition Flashcards
What is the structure of hCG? What receptors does it act on?
It is made of alpha and beta subunits. As the alpha subunit is identical to that of FSH, LH and TSH it can act on LH receptors.
What is the function of hCG?
It maintains the corpus luteum.
Stimulates DHEA production in the fetal adrenals which is converted to testosterone in males to produce masculinity.
Which part of the embryo secretes hCG?
the syncytiotrophoblast
What produces progesterone through pregnancy and what are its actions?
Progesterone is initially produced by the corpus luteum but then switches to placental production at 6-8weeks. Its action is to relax the myometrium (downregulation of contractile proteins) and maintain the decidua (pregnant endometrium). This means progesterone supresses birth.
What are the three types of oestrogen and what do they regulate?
Oestrone, E1: predominates in menopause
Oestrodiol E2: regulates menstruation
Oestriol E3: pregnancy specific
Where is the main source of oestrogens post implantation?
The placenta and fetal liver
What are the effects of increased E2 production after pregnancy?
Mainly maternal effects:
- causes vascular changes (vasodilation and increased clotting)
- increased contractile proteins
What is placental growth hormone and when is it produced?
It is produced from 15-20 weeks. modifies receptors to transport glucose to fetal compartment and causes increased maternal gluconeogenesis. Receptor only functional near term.
How can myometrial contraction be initiated?
By giving a progesterone antagonist
The cervical dilation is known as the active phase, what comes before this?
The latent phase which is when changes to the cervix (breakdown of collagen etc) take place.
What hormones contribute to breast development?
human placental lactogen and prolactin. HPL is homologous with growth hormone and prolactin and causes insulin resistance to increase.
What does suckling increase?
Prolactin production so continual milk production
Oxytoxin production that causes smooth muscle contraction and milk ejection
