HSC BIO HORMONES

Progesterone (pregnancy)

Maintains the uterine lining (endometrium) for embryo implantation and prevents uterine contractions.

Oestrogen (pregnancy)

Helps develop the uterus and placenta; promotes growth of breast tissue for lactation.

hCG

Maintains corpus luteum in early pregnancy so it continues to produce progesterone; detected in pregnancy tests.

Progesterone (menstrual cycle)

Secreted after ovulation; thickens and maintains the endometrium to prepare for possible pregnancy.

Oestrogen (menstrual cycle)

Stimulates growth of the uterine lining in the first half of the cycle; triggers LH surge for ovulation. (ALSO IN CHARGE OF DEVELOPMENT OF FEMALE SECONDARY SEXUAL CHARACTERISTICS)

Testosterone

Develops male reproductive organs and secondary sexual characteristics (e.g. facial hair, deep voice); supports sperm production.

Relaxin

Produced During Pregnancy: Relaxes ligaments in the pelvis and softens the cervix to prepare for childbirth

Cortisol

Stress hormone that helps regulate metabolism, immune response, and blood pressure; also involved in fetal development during pregnancy. It stimulates the placenta to increase oestrogen (oestriol) production, which is a key trigger for labour.

Oestriol

• Oestriol levels rise sharply in the final weeks of pregnancy, signalling that the fetus is mature and labour is approaching.

• Increases uterine sensitivity to oxytocin, a hormone that stimulates contractions

• high levels indicate healthy fetal development and placenta function

Oxytocin

• Produced by: Hypothalamus, released by posterior pituitary

• Function: Stimulates strong uterine contractions during labour

• Feedback: Works via a positive feedback loop — more contractions → more oxytocin

• Post-birth: Helps expel placenta and reduces bleeding; also triggers milk let-down in breastfeeding

GnRH

• Pregnancy: Usually suppressed during pregnancy.

• Normal Function: Stimulates pituitary to release FSH and LH, initiating the menstrual cycle.

Insulin

Function: Lowers blood glucose levels by promoting glucose uptake into cells and storage as glycogen in the liver.

Glucagon

• Function: Raises blood glucose levels by promoting the breakdown of glycogen into glucose in the liver

Auxins

• Promote cell elongation and are involved in phototropism (growth towards light) and root development

Cytokinins

Promote cell division and growth, especially in shoots and buds; delay leaf aging

Gibberellins

Stimulate seed germination, stem elongation, and flowering

Abscisic acid

Inhibits growth, promotes dormancy, and closes stomata during water stress (drought response).

Ethylene

Promotes fruit ripening and leaf fall (abscission); also involved in response to mechanical stress