Your sexual response

Hormones are substances that affect how your body works. They act as messengers carrying information and instructions from one group of cells to another. Hormones control many of the body’s functions, including growth, development and reproduction.

Male sex hormones

The major male sex hormone is testosterone, which is produced mostly in the testicles and also in the adrenal glands (found on top of the kidneys). Testosterone causes a man’s reproductive organs to develop and is responsible for other sexual characteristics, such as a deep voice and facial hair. Cancer treatments that lower a man’s hormone levels, such as testosterone-blocking drugs for prostate cancer, can affect his ability to get or keep an erection and reduce his desire for sex.

Female sex hormones

The major female sex hormones are oestrogen and progesterone. Oestrogen keeps the vagina moist and supple, while progesterone controls reproduction. Both these hormones are produced mostly in the ovaries until menopause, when the ovaries cease releasing eggs and periods stop. A small amount is made in the adrenal glands (found on top of the kidneys) before and after menopause. Some cancer treatments can affect women’s hormone levels in the short and long term, sometimes causing early menopause or menopause-like symptoms.

In women, the ovaries and adrenal glands also make small amounts of the male sex hormones (androgens). Androgen levels seem to be linked with a woman’s sexual desire. They decrease during and after chemotherapy and can drop abruptly if the ovaries are removed.

A man’s external sex organs (genitals) are the penis and scrotum:

• penis – the main male sex organ. It has three parts: the root, where the penis joins the abdomen; the shaft, the length of the penis; and the glans, the cone-shaped end. The glans is covered by a loose layer of skin called the foreskin, unless the foreskin has been removed by circumcision. The ridge on the underside of the glans, called the frenulum, is usually the most sensitive part of the penis. At the tip of the glans is a slit opening to the urethra, through which semen and urine pass
• scrotum – a loose pouch of skin at the base of the penis that holds the testicles. It acts as a ‘climate-control system’ for the testicles, keeping them slightly cooler than the rest of the body to allow for normal sperm development.

There are several other parts in a man’s reproductive system:

• testicles (also called testes) – two egg-shaped glands held in the scrotum. They make and store sperm and produce the male sex hormone, testosterone.
• epididymes – coiled tubes on the outer surface of the testicles. The immature sperm travel from each testicle to the epididymes, where they mature
• prostate – a small gland about the size of a walnut that sits below the bladder, deep in the pelvis. It surrounds the urethra, which carries urine from the bladder. The prostate produces fluids that form part of the semen
• seminal vesicles – glands that lie very close to the prostate and produce secretions that form part of the semen
• vas deferens – the tubes joining the testicles and the penis.

A woman’s external sex organs (genitals) are collectively referred to as the vulva:

• clitoris – the main sexual pleasure organ for women. It is located where the labia minora join. The clitoris is made up of highly sensitive erectile tissue and becomes erect during arousal
• mons pubis – the area of fatty tissue covered with pubic hair
• labia majora – the outer lips of the vulva
• labia minora – the inner lips of the vulva
• Bartholin glands – two small glands near the opening of the vagina. They produce mucus to lubricate the vagina.

Beneath the clitoris is the urethra, for passing urine. Further back is the entrance to the vagina. Beyond that is an area of skin called the perineum, and beyond that is the anus.

Several parts of a woman’s reproductive system are inside her body:

• vagina (birth canal) – a muscular sheath or canal that extends from the neck of the uterus (cervix) to the vulva
• uterus (womb) – a hollow muscular organ where a fertilised egg (ovum) is nourished to form a baby
• cervix – the neck of the uterus
• fallopian tubes – two long, thin tubes that extend from the uterus and open near the ovaries. These tubes carry sperm to the eggs, and carry the eggs from the ovaries to the uterus
• ovaries – two small glands found on either side of the uterus, near the end of the fallopian tubes. The ovaries contain eggs and produce the female sex hormone, oestrogen and progesterone, as well as small amounts of male sex hormones (androgens).

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