Puberty

Puberty is the stage of human growth and development in which a person becomes physically mature.

The changes are as follows:

For boys:

• Facial hair starts to grow and hair appears in pubic region and under armpits.
• The sex organs increase in size.
• Production of sperms start.
• Larynx enlarges and voice deepens.

For girls:

• Hair appears in the pubic region and under armpits.
• The breasts and uterus enlarge, hips broaden.
• Menstruation and ovulation start.

The girls will also start going through what is called a menstrual cycle.

The changes of the Graafian follicle: 

The Graafian follicle is the basic unit of the female reproductive biology, each of which is composed of roughly spherical aggregations of cells found in the ovary.

1. Graafian follicle

• contains egg surrounded by follicle cells and a fluid-filled space
• egg has haploid number of chromosomes

1. Ovulation

• about 14th day from the beginning of menstruation, Graafian follicle ruptures and releases the egg into the oviduct funnel

1. Corpus Luteum

• over ovulation, Graafian follicle develops into a corpus luteum
• Corpus luteum prodeces progesterone that prepares body for pregancy

1. Corpus Luteum breaks down

• fertilisation occurs, Corpus Luteum breaks down

The stages:

1. Menstrual flow stage (day 1-5)

• Uterine lining (endometrium) breaks down and flows from the uterus out of the body through the vagina

- Anterior pituary gland secrets follicle-stimulating hormone (FSH) into the bloodstream

1. Follicle stage (day 6-13)

Effects of the FSH

• FSH stimulates the development of the follicles in the ovaries. One follicle matures to become the Graafian follicle in one of the ovaries during each cycle
• It stimulates the follicles in ovaries to secrete oestrogen

1. Effects of oestrogen

• Causes the repair and growth of endometrium 
• Endometrium becomes thick and spongy with blood vessels
• High concentration of oestrogen in bloodstream

. inhibits FSH production, preventing ripening and growth of more follicles

. ripening and growth of more follicles 

. stimulates pituitary gland to secrete luteinising hormone (LH)

1. Ovulation (day 14)

Effects of LH

• LH causes ovulation
• Causes the formation of the corpus luteum
• Corpus luteum secretes progesterone and some oestrogen

1. Corpus luteum stage (day 15-28) 

Effects of progesterone

• Maintains the uterine lining by causing it to thicken further and be supplied with blood capillaries, preparing it for the fertilised egg
• It inhibits ovulation
• It inhibits FSH production