HCG + PREGNANCY + Blastocyst + implantation

What produces hCG and when?

The trophoblast (after implantation) secretes hCG. It later develops into the placenta.

What is the function of hCG in pregnancy?

hCG maintains the corpus luteum so it continues producing progesterone.

Why is progesterone important in pregnancy?

It maintains the endometrium and supports pregnancy by preventing its breakdown.

How do pregnancy tests work?

They detect hCG in urine using monoclonal antibodies specific to hCG.

What is a blastocyst?

A hollow ball of cells formed after repeated mitotic divisions of the zygote.

What are the parts of a blastocyst?

• Inner cell mass → develops into embryo

• Trophoblast → develops into placenta

What is implantation?

The blastocyst embedding into the endometrium of the uterus.

What does the placenta do?

• Exchanges oxygen, nutrients, and waste

• Produces hormones

• Maintains pregnancy

Why is the placenta efficient?

It has chorionic villi which increase surface area for exchange.

What maintains pregnancy early on?

The corpus luteum secretes progesterone (maintained by hCG).

How does hormone production change later in pregnancy?

The placenta takes over progesterone production from the corpus luteum.

What does progesterone do during pregnancy?

Maintains endometrium and prevents uterine contractions.

What triggers childbirth?

Decreasing progesterone and increasing oxytocin release.

How does oxytocin control labour?

It stimulates uterine contractions.

What is the positive feedback loop in labour?

Contractions → more oxytocin → stronger contractions → even more oxytocin.

What is the hormonal pathway controlling puberty?

Hypothalamus (GnRH) → pituitary (FSH + LH) → gonads → sex hormones.

What do FSH and LH do?

hey stimulate the gonads (testes/ovaries) to produce sex hormones and gametes.

What hormones are produced by gonads?

• Testosterone

• Oestrogen

• Progesterone

What changes occur during puberty?

Development of reproductive organs, secondary sexual characteristics, and gamete production.