Females Hormones Levels in Humans

Female Hormone Levels in Humans:

 

  • In humans, the female hormone levels vary throughout the menstrual cycle and at different stages of life. 
  • The primary female hormones are oestrogen, progesterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH). 
  • Here's a breakdown of the hormonal changes:

Menstrual Cycle: 

- Reproductive cycle in female primates (e.g., humans) characterised by the release of one ovum (ovulation) and recurring menstruation.

- Menarche: Onset of the first menstruation at puberty.

- Menstrual Cycle Length: Average interval between two menstrual periods is around 28/29 days.

- Major Events in Menstrual Cycle: Menstrual phase (3-5 days of menstrual flow), follicular phase, ovulation, and luteal phase.

1. Menstrual Phase:

  • Menstrual flow occurs due to the breakdown of the endometrial lining of the uterus. 
  • Lasts for 3-5 days. Occurs if the released ovum is not fertilised.
  • Lack of Menstruation: Lack of menstruation may indicate pregnancy or other underlying causes like stress or poor health.

2. Follicular Phase: 

  • Primary follicles in the ovary grow into mature Graafian follicles. 
  • Endometrium of the uterus regenerates. 
  • Changes induced by pituitary and ovarian hormones.
  • Hormone Levels in Follicular Phase: Gonadotropins (LH and FSH) gradually increase, stimulating follicular development and oestrogen secretion by the growing follicles.
  • LH Surge and Ovulation: LH levels peak around the 14th day of the cycle, leading to the rupture of the Graafian follicle and release of the ovum (ovulation). Estrogen levels peak just before ovulation.

3. Luteal Phase: 

  • Remaining parts of the Graafian follicle transform into the corpus luteum. 
  • Corpus luteum secretes progesterone, essential for maintaining the endometrium for potential implantation of a fertilised ovum.

 

Diagrammatic representation of various events during a menstrual cycle

Menstruation or Pregnancy: 

  • If fertilisation doesn't occur, the corpus luteum degenerates, causing disintegration of the endometrium and menstruation. 
  • During menstruation, the decreasing levels of oestrogen and progesterone lead to the shedding of the uterine lining, resulting in menstrual bleeding. 
  • Hormone levels gradually start to rise again as the menstrual cycle progresses into the follicular phase.
  • In pregnancy, all events of the menstrual cycle cease.
  • During pregnancy, the placenta produces high levels of oestrogen and progesterone to support the development of the foetus.
  • Oestrogen and progesterone play crucial roles in maintaining the uterine lining and preventing menstruation during pregnancy.

Menopause:

  • Menopause is a natural stage in a woman's life when menstrual cycles cease, usually occurring between the ages of 45 and 55.
  • During menopause, there is a significant decline in oestrogen and progesterone production. FSH and LH levels may rise.