Diagram of the Male Reproductive System

Ejaculation is the ejecting of semen from the penis, and is usually accompanied by orgasm. Physiological aspects Internal and external fertilization Depending on the Species, spermatozoa can fertilize The penis (plural penises, penes An orgasm (sexual climax is the conclusion of the plateau phase of the sexual response cycle, and may be experienced by both males and females It is usually the result of sexual stimulation, which may include prostate stimulation. Sexual stimulation is any stimulus that leads to sexual arousal or Orgasm. The prostate (from Greek προστάτης - prostates, literally "one who stands before" "protector" "guardian" is a Rarely, it is due to prostatic disease. Ejaculation may occur spontaneously during sleep (a nocturnal emission). Sleep is a Natural state of bodily rest observed throughout the animal kingdom A nocturnal emission is an Ejaculation of Semen experienced by a male during Sleep. Anejaculation is the condition of being unable to ejaculate.

Sequence of a male ejaculation.

Phases

Realtime video example of "ejaculation proper".

Ejaculation has two phases: emission and ejaculation proper. The emission phase of the ejaculatory reflex is under control of the sympathetic nervous system, while the ejaculatory phase is under control of a spinal reflex at the level of the spinal nerves S2-4 via the pudendal nerve. The Sympathetic Nervous System ( SNS) is a branch of the Autonomic nervous system along with the Enteric nervous system and Parasympathetic nervous Tendon reflex (or T-reflex) is a feedback mechanism that controls increasing muscle tension by causing muscle relaxation before tension force becomes so great it may damage the The term spinal nerve generally refers to the mixed spinal Nerve, which is formed from the dorsal and ventral roots that come out of the Spinal cord. The pudendal nerve is a Nerve in the pelvic region that innervates the external genitalia of both sexes as well as sphincters for the bladder and the Rectum A refractory period succeeds the ejaculation, and sexual stimulation precedes it.

Emission

During emission, the two ducts known as vas deferens contract to propel sperm from the epididymis where it was stored up to the ampullae at the top end of the vas deferens. The vas deferens (plural vasa deferentia also called ductus deferens, ( Latin: "carrying-away vessel" is part of the Male Anatomy A spermatozoon or spermatozoan ( pl spermatozoa) from the Ancient Greek σπέρμα (seed and ζῷον (living being and more commonly known The epididymis is part of the Human Male Reproductive system and is present in all male Mammals It is a narrow tightly-coiled Tube At the fundus of the bladder the Ductus deferens becomes enlarged and tortuous and this portion is termed the ampulla. The beginning of emission is typically experienced as a "point of no return," also known as point of ejaculatory inevitability. The sperm then passes through the ejaculatory ducts and is mixed with fluids from the seminal vesicles, the prostate, and the bulbourethral glands to form the semen, or ejaculate. The Ejaculatory ducts ( ductus ejaculatorii) are paired structures in male Anatomy, about 2 cm in length The seminal vesicles ( glandulae vesiculosae) are a pair of simple tubular glands posteroinferior to the Urinary bladder of males The prostate (from Greek προστάτης - prostates, literally "one who stands before" "protector" "guardian" is a A bulbourethral Gland (or Cowper 's gland) is one of two small Exocrine glands present in the Reproductive system of human males Physiological aspects Internal and external fertilization Depending on the Species, spermatozoa can fertilize During ejaculation proper, the semen is ejected through the urethra with rhythmic contractions. In Anatomy, the urethra (from Greek ουρήθρα - ourethra) is a tube which connects the Urinary bladder to the outside of ^[1]

Ejaculation proper

These rhythmic contractions are part of the male orgasm. They are generated by the bulbospongiosus muscle. Bulbospongiosus ( bulbocavernous in older texts is one of the superficial Muscles of the Perineum. The typical male orgasm lasts about 17 seconds but can vary from a few seconds up to about a minute. After the start of orgasm, pulses of semen begin to flow from the urethra, reach a peak discharge and then diminish in flow. The typical orgasm consists of 10 to 15 contractions, each bringing an extremely pleasurable sensation to the head of the penis. Once the first contraction has taken place, there is nothing the male can do to prevent ejaculation taking place. The rate of contractions gradually slows during the orgasm. Initial contractions occur at an average interval of 0. 6 seconds with an increasing increment of 0. 1 second per contraction. Contractions of most men proceed at regular rhythmic intervals for the duration of the orgasm. Many men also experience additional irregular contractions at the conclusion of the orgasm. ^[2]

Semen content

Sertoli cells, which nurture and support developing spermatocytes, secrete a fluid into seminiferous tubules that helps transport spermatozoa to the genital ducts. The Ductuli Efferentes possess cuboidal cells with microvilli and lysosomal granules that modify the semen by reabsorbing some fluid. Once the semen enters the Ductus Epididymis the principle cells, which contain pinocytotic vessels indicating fluid reabsorption, secrete glycerophosphocholine which most likely inhibits premature capacitation. This article is about a biological process related to reproduction for the other use see Capacitation (NGO. The accessory genital ducts, the seminal vesicle, prostate glands, and the bulbourethral glands, produce most of the seminal fluid. The seminal vesicles ( glandulae vesiculosae) are a pair of simple tubular glands posteroinferior to the Urinary bladder of males The prostate (from Greek προστάτης - prostates, literally "one who stands before" "protector" "guardian" is a A bulbourethral Gland (or Cowper 's gland) is one of two small Exocrine glands present in the Reproductive system of human males The seminal vesicles produce a yellowish viscous fluid rich in fructose and other substances that makes up ~70% of human ejaculate. The prostatic secretion, influenced by dihydrotestosterone, is a whitish, thin fluid containing proteolytic enzymes, citric acid, acid phosphatase and lipids. The bulbourethral glands secrete a clear secretion into the lumen of the urethra to lubricate it. In Anatomy, the urethra (from Greek ουρήθρα - ourethra) is a tube which connects the Urinary bladder to the outside of Semen begins to spurt from the penis during the first or second contraction of orgasm. For most men the first spurt occurs during the second contraction. A small sample study of seven men showed between 26 and 60 percent of the contractions during orgasm were accompanied by a spurt of semen. ^[3]

Refractory period

Most men experience a lag time between the ability to ejaculate consecutively, and this lag time varies among men. Age also affects the recovery time; younger men typically recover faster than older men. During this refractory period it is difficult or impossible to attain an erection, because the sympathetic nervous system counteracts the effects of the parasympathetic nervous system. In sexuality the refractory period is the recovery phase after Orgasm during which it is physiologically impossible for an individual to have additional orgasms The erection of the Penis, Clitoris or a Nipple is its enlarged and firm state The Sympathetic Nervous System ( SNS) is a branch of the Autonomic nervous system along with the Enteric nervous system and Parasympathetic nervous

Stimulation

See also: Sexual stimulation

There are wide variations in how long sexual stimulation can last before ejaculation occurs. Sexual stimulation is any stimulus that leads to sexual arousal or Orgasm.

When a man ejaculates before he wants to it is called premature ejaculation. Premature ejaculation (PE also known as rapid ejaculation, rapid climax, premature climax or early ejaculation, is the most common sexual If a man is unable to ejaculate in a timely manner after prolonged sexual stimulation, in spite of his desire to do so, it is called delayed ejaculation or anorgasmia. Delayed ejaculation, also known as retarded Ejaculation and ejaculation incompetence is the inability to ejaculate or persistent difficulty in achieving Orgasm despite Anorgasmia (often related to Delayed ejaculation in males is a form of Sexual dysfunction sometimes classified as a Psychiatric disorder in which the patient An orgasm that is not accompanied by ejaculation is known as a dry orgasm. An orgasm (sexual climax is the conclusion of the plateau phase of the sexual response cycle, and may be experienced by both males and females

Volume

The force and amount of ejaculate vary widely from male to male. In Physics, a force is whatever can cause an object with Mass to Accelerate. A normal ejaculation may contain anywhere from 1. 5 to 5 milliliters. The litre or liter (see spelling differences) is a unit of Volume. ^[4] Adult ejaculate volume is affected by the amount of time that has passed since the previous ejaculation. Larger ejaculate volumes are seen with greater durations of abstinence. However, a recent Australian study has suggested a positive correlation between prostate cancer and infrequent ejaculation and/or prostate milking, which performs essentially the same function. Prostate massage and prostate milking are terms used to describe the Massage or stimulation of the Prostate gland in males either for medical or Sexual That is, frequent ejaculation appears to reduce the risk of prostate cancer. Frequent ejaculation is more easily obtained and sustained over time with the aid of masturbation and it is these ejaculations which are important, not the mechanism. ^[5] Also, the duration of the stimulation leading up to the ejaculation can affect the volume. Abnormally low volume is known as hypospermia, though it is normal for the amount of ejaculate to diminish with age. Hypospermia is the medical term when a man has an unusually low Ejaculate (or Semen) volume it is the logical opposite of Hyperspermia.

Quality

Main article: Semen quality

The number of sperm in an ejaculation also varies widely, depending on many factors, including the recentness of last ejaculation, the average warmth of the testicles, the degree and length of time of sexual excitement prior to ejaculation, the age, testosterone level, the nutrition and especially hydration and the total volume of seminal fluid. Semen quality is a measure of the ability of Semen to accomplish Fertilisation. A spermatozoon or spermatozoan ( pl spermatozoa) from the Ancient Greek σπέρμα (seed and ζῷον (living being and more commonly known The testicle (from Latin testiculus, diminutive of testis, meaning "witness" virility plural testes) is the male Testosterone is a Steroid hormone from the Androgen group In mammals testosterone is primarily secreted in the testes of males and the Ovaries The volume of any solid plasma vacuum or theoretical object is how much three- Dimensional space it occupies often quantified numerically An unusually low sperm count, not the same as low semen volume, is known as oligospermia, and the absence of any sperm from the ejaculate is termed azoospermia. Oligospermia stands for low semen volume and is often mistaken for Oligozoospermia, which means few "animals" (spermatozoa in semen - a medical Symptom Azoospermia is the Medical condition of a male not having any measurable level of sperm in his Semen.

Pleasure

Each contraction is associated with a wave of sexual pleasure, especially in the penis and loins. The loins are the sides between the lower Ribs and Pelvis, and the lower part of the Back. The first and second convulsions are usually the most intense in sensation, and produce the greatest quantity of semen. Thereafter, each contraction is associated with a diminishing volume of semen and a milder wave of pleasure.

Ejaculate development during puberty

The first ejaculation in males occurs about 12 months after the onset of puberty. This first ejaculate volume is small. The typical ejaculation over the following three months produces less than 1 ml of semen. The semen produced during early puberty is also typically clear. After ejaculation this early semen remains jellylike and unlike semen from mature males fails to liquify. Most first ejaculations (90 percent) lack sperm. Of the few early ejaculations that do contain sperm, the majority of sperm (97%) lack motion. The remaining sperm (3%) have abnormal motion. ^[6]

As the male proceeds through puberty, the semen develops mature characteristics with increasing quantities of normal sperm. Semen produced 12 to 14 months after the first ejaculation liquifies after a short period of time. Within 24 months of the first ejaculation, the semen volume and the quantity and characteristics of the sperm match that of adult male semen. ^[6]

Central nervous system control

To map the neuronal activation of the brain during the ejaculatory response, researchers have studied the expression of c-fos, a proto-oncogene expressed in neurons in response to stimulation by hormones and neurotransmitters ^[7] Expression of c-fos in the following areas have been observed: ^[8],^[9]

• medial preoptic area (MPOA)
• lateral septum, bed nucleus of the stria terminalis
• paraventricular nucleus of the hypothalamus (PVN)
• ventromedial hypothalamus, medial amygdala
• ventral premammillary nuclei
• ventral tegmentum
• central tegmental field
• mesencephalic central gray
• peripeduncular nuclei
• parvocellular subparafascicular nucleus (SPF) within the posterior thalamus

Fertilization

Main article: Fertilization

During heterosexual intercourse, the vagina provides sexual stimulation to the penis, typically resulting in orgasm and ejaculation. For soil improvement see Fertilization (soil. Sexual intercourse, in its biological sense is the act in which the male reproductive organ (in humans and other higher animals enters the female reproductive tract The vagina (from Latin, literally " Sheath " or " Scabbard " is a fibromuscular tubular tract leading from the Uterus Normally, ejaculation is required for emission of sperm; if ejaculation happens while the penis is either near or within the woman's vagina, sperm can then travel into the uterus and fertilize an egg if present, impregnating the woman. A spermatozoon or spermatozoan ( pl spermatozoa) from the Ancient Greek σπέρμα (seed and ζῷον (living being and more commonly known An ovum (plural ova) is a Haploid Female reproductive cell or Gamete. For soil improvement see Fertilization (soil. However, almost all men produce a small amount of pre-ejaculate fluid when their penis is erect and they are sexually stimulated, and this pre-ejaculate may contain some sperm which can also lead to pregnancy. Pre-ejaculate (also known as pre-ejaculatory fluid or Cowper's fluid, and colloquially as pre-cum) is the clear colorless viscous fluid that For this reason, coitus interruptus may still lead to unwanted pregnancies for couples engaging in vaginal intercourse if other forms of birth control are not used as well. Coitus interruptus, also known as withdrawal or the pull-out method, is a method of Contraception in which a couple has Sexual intercourse Birth control, sometimes synonymous with contraception, is a regimen of one or more actions devices or Medications followed in order to deliberately prevent See also artificial insemination. AIH redirects here For the indie rock band abbreviated AIH see Architecture in Helsinki Artificial insemination (AI is the process by which

See also

• Aspermia
• Azoospermia
• Coitus interruptus
• Coitus reservatus
• Delayed ejaculation
• Female ejaculation
• Retrograde ejaculation
• Keri - ejaculation in Jewish law

References