Everything about The Erection totally explained
The
erection of the
penis,
clitoris or a
nipple is its enlarged and firm state. It depends on a complex interaction of psychological, neural, vascular and endocrine factors.
The ability to maintain the erectile state is key to the reproductive system and many forms of life couldn't reproduce in a natural way without this ability.
Penis erection
A penis erection occurs when two tubular structures that run the length of the penis, the
corpora cavernosa, become engorged with venous blood. This may result from any of various
physiological stimuli, also known as sexual arousal. The
corpus spongiosum is a single tubular structure located just below the
corpora cavernosa, which contains the
urethra, through which
urine and
semen pass during
urination and
ejaculation, respectively. This may also become slightly engorged with blood, but less so than the corpora cavernosa. After a man has ejaculated during sexual encounter or
masturbation, his erection usually ends, but this may take time depending on the length and thickness of the penis.
Penis erection usually results from exposure to sexual stimulation from
sexual arousal, but can also occur by such causes as a full
urinary bladder or spontaneously during the course of a day or at night, often during REM sleep (see "
nocturnal penile tumescence"). An erection results in swelling, hardening and enlargement of the penis. Erection enables
sexual intercourse and other
sexual activities (
sexual functions), though it isn't essential for all sexual activities. An erection may also occur once woken up, called
nocturnal penile tumescence. The scrotum may also become tightened during an erection.
Autonomic control
In the presence of mechanical stimulation, erection is initiated by the
parasympathetic division of the
autonomic nervous system (ANS) with minimal input from the central nervous system. Parasympathetic branches extend from the
sacral plexus into the
arteries supplying the erectile tissue; upon stimulation, these nerve branches initiate the release of nitric oxide, a
vasodilating agent, in the target arteries. The arteries dilate, filling the
corpora spongiosum and
cavernosa with blood. Erection subsides when parasympathetic stimulation is discontinued; baseline stimulation from the
sympathetic division of the ANS causes constriction of the penile arteries, forcing blood out of the erectile tissue.
The
cerebral cortex can initiate erection in the absence of direct mechanical stimulation (in response to visual, auditory, olfactory, imagined, or tactile stimuli) acting through erectile centers in the lumbar and sacral regions of the spinal cord. The cortex can suppress erection even in the presence of mechanical stimulation, as can other psychological, emotional, and environmental factors.
The opposite term is .
Shape and size
An erect penis can take on a number of different shapes and angles, ranging from a straight tube angled at a 45-90 degree angle, to a curvature to the left or right (see image), up or down. A tightly curved penis, known as
Peyronie's disease, is identified by a severe curve in the erect penis. This may cause physical and psychological effects for the affected individual, which could include
erectile dysfunction or pain during erection. Treatments include oral medication (such as Vitamin E) or surgery, which is most often reserved as a last resort.
Generally the size of an erect penis is fixed throughout post-
pubescent life. Its size may be increased by surgery, although the procedure is controversial, and mostly the results are disappointing. Penile enlargement is a controversial subject. See
Penis enlargement.
Erectile dysfunction
Erectile dysfunction (also known as ED or '(male) impotence') is a
sexual dysfunction characterized by the inability to develop or maintain an erection. It can occur due to both
physiological and
psychological reasons, most of which are amenable to treatment. Common physiological reasons include
cardiovascular leakage and
diabetes. Some drugs also may cause erectile dysfunction in patients who received them such as
lithium,
paroxetine, etc.; often unnecessary since in most cases the matter can be helped. There is a strong
culture of silence and inability to discuss the matter. In fact around 1 in 10 men will experience recurring impotence problems at some point in their lives.
The study of erectile dysfunction within medicine is covered by
andrology, a sub-field within
urology.
Clitoral erection
Clitoral erection is a part of
sexual arousal in women. The
clitoris is the anatomically homologous counterpart of the penis, and the physiological mechanism of its erection is similar.
Swelling and enlargement may also occur during a clitoral erection but because a large proportion of the clitoris is within the body and its drastically reduced size, it's often not as obvious.
Nipple erection
Nipple erection may result from three kinds of response. It happens in females during
breast feeding. It is also an early part of the sexual response in females and males. Both of these are caused by the release of
oxytocin. Nipple erection can also be caused by a tactile response to cold temperature in both males and females. The erection of nipples isn't due to
erectile tissue, but due to the contraction of
smooth muscle under the control of the
autonomic nervous system. It is more akin to a
hair follicle standing on end than to a sexual erection.
Further Information
Get more info on 'Erection'.
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