HHDPhysical characteristics of youths’ development

(Part 2)

The Menstrual Cycle

Signifies a woman’s ability to bear children

Menarche usually occurs between 11-14 years of age

On average, a menstrual cycle lasts 28 days

Involves a delicate interplay of hormones

Oestrogen, Progesterone, FSH and LH are all present during the menstrual cycle. However, the release of and contribution of these hormones occurs at different stages during the 28 day cycle.

The menstrual cycle explained

The Menstrual Cycle

Day 1-7- Bleeding commences- Lining of uterus (endometrium) is discharged- Pituitary gland releases FSH which travels in bloodstream to

the ovaries- FSH stimulates an ovum to start maturing in follicle- Follicles are small sacs that contain an immature ovum as it

developsFallopian Tube

Day 7-12- As follicles begin to mature, oestrogen is released by the

ovaries- Oestrogen travels to the uterus where it stimulates the

growth of a new blood lining to prepare for possible pregnancy

(blood lining)

Oestrogen

Day 13-15- High Oestrogen levels cause the pituitary gland

to switch from making FSH to LH, which stimulates ovulation

Oestrogen

LH

Day 14. Ovulation- The LH hormone causes the follicle to burst,

releasing an egg from an ovary into the fallopian tube.

- This process is called ovulation - Peak fertility time - The empty follicle is now called the corpus

luteum

Day 15-28- Ovum travels down fallopian tube and into uterus- Follicle keeps on making Oestrogen and Progesterone which

causes the endometrium to continue to thicken in case conception occurs

- If ovum is fertilised by sperm it implants into endometrium- Unfertilised egg dies- At end of cycle, hormone levels drop and next menstrual

cycle beings on day 28

Endometrium continues to thicken

Ovum

Follicle

Progesterone

Oestrogen