The male's sex organ comprises the penis and two testicles. The testicles are contained in a bag of skin called the scrotum.
The internal structure of the penis contains three long tubes:
Two corpora cavernosa which run along the length of the penis
The corpus spongiosum, which runs along the underside of the shaft of the penis. This includes the urethra through which urine and semen pass.
The head of the penis is called the glans. This is covered by a sleeve-like layer of loose skin called the foreskin. A fold of skin, the frenulum, joins the foreskin to the underside of the glans. Sometimes, a ring of small spots appears around the glans, usually in early adulthood. These are known as pearly papules and are harmless.
The muscles located at the base of the penis have a role to play in erection. In addition, these move rhythmically during orgasm.
The testicles contain two different types of cells. One produces testosterone and the other produces sperm. Sperm moves from the testicles into the epididymis (a collection of small tubes) and then into another tube called the vas deferens. When vasectomies are performed it is the vas deferens that is cut.
Behind the bladder, the male has a storage area for sperm. Two small glands (seminal vesicles) produce seminal fluid, which is mixed with the sperm and other fluid from the prostate to form semen. This is ejaculated during orgasm. The clear fluid sometimes seen during the period of early arousal is produced by other glands but may contain enough sperm to lead to pregnancy in the partner.
When a man is sexually aroused, the penis becomes erect. This is caused by increased blood flow to the penis, while simultaneously, blood flow out of the penis stops. The muscles at the base of the penis contract to maintain the erection.
When orgasm occurs, the semen that has collected at the top of the urethra is forced down and out of the tip of the penis by muscular action. After orgasm the man becomes unresponsive to further sexual stimulation and may often want to sleep. This period can vary from minutes to hours.
Painful sex in men is nearly always physical and usually caused by a skin problem, such as an infection. Psychological problems are more likely to lead to problems with erection.
There are a number of possible reasons for painful sex including:
Infections (thrush, sexually transmitted diseases)
Trauma to the penis
Over-active cremaster muscle
Priapism (failure of the erection to subside for hours).
Problems with the penis
Premature ejaculation (coming too soon) is the most common of all sexual difficulties. The cause is usually psychological and the most effective way of dealing with this is to become familiar with techniques to control ejaculation. However, if the problem develops suddenly, prostate or neurological problems may need to be considered and advice from a doctor should be sought.
Erectile problems may occur for a number of reasons. However, if medical advice is sought, it can be successfully treated in most cases.
Peyronie's disease (bent penis) is a disorder in which hardened cells form under the skin on one side of the penis. It begins as a localised inflammation and can develop into a hardened scar, which causes the bend. It can cause loss of erection and pain. Penetration during sexual intercourse may become impossible. Medical advice is necessary.
Balanitis (inflammation of the glans) is caused by infection, irritation, tight foreskin or trauma to the penis. The main symptoms are a painful or itchy feeling. Occasionally there may be penile discharge or a burning sensation when urinating. Medical advice is useful and creams or antibiotics may be needed to clear this up.
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