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The functions of the reproductive organs are strongly influenced by hormones. The main reproductive hormones differ between males and females:
Adolescence is the period when a person approaches sexual maturity. During this time:
Puberty is the point at which sexual maturity is reached. This typically occurs a few years earlier in girls than in boys.
It's important to note that reaching puberty does not mean complete adulthood, as brain development and changes continue beyond this point.
Testosterone is secreted by the testes in males. During adolescence, the quantity of testosterone secreted greatly increases, triggering the development of secondary sexual characteristics.
The increased testosterone levels during puberty cause:
Oestrogen is secreted by the ovaries in females. This hormone is responsible for the development of female secondary sexual characteristics during puberty.
Oestrogen causes:
The menstrual cycle is a recurring sequence of events that prepares the female body for potential pregnancy. Understanding this cycle requires knowledge of changes in both the ovaries and the uterus lining.
Follicles are small structures within the ovaries where eggs develop. After puberty, typically one egg is released from a follicle into the oviduct every month through a process called ovulation.
Preparation Phase: Before the egg is released, the lining of the uterus becomes thick and spongy to prepare for a potential zygote. This lining is rich in tiny blood vessels that would supply the embryo with nutrients and oxygen if fertilization occurs.
Menstruation: If the egg is not fertilised, the spongy lining is not needed. It gradually breaks down and is lost through the vagina. This process is called menstruation or a period, and it typically lasts about five days.
Rebuilding Phase: After menstruation, the uterus lining builds up again to be ready to receive the next egg if it is fertilised.
The menstrual cycle can be divided into four main stages:
Stage 1 - Follicle Development: Inside the ovary, a follicle containing an egg cell develops. Simultaneously, the uterus lining is repaired after menstruation.
Stage 2 - Ovulation: The follicle bursts, releasing an egg cell from the ovary. This is when fertilisation could take place.
Stage 3 - Corpus Luteum Formation: The follicle transforms into a structure called the corpus luteum (also known as a yellow body). The uterus lining becomes more vascular and thicker, ready to receive an embryo.
Stage 4 - Menstruation (if no fertilisation): If the egg has not been fertilised, the thick uterus lining is not needed. It breaks down and is gradually lost through the vagina.
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