Main article: Ejaculation Ejaculation is the ejecting of semen from the penis, and is usually accompanied by orgasm. A series of muscular contractions delivers semen, containing male gametes known as sperm cells or spermatozoafrom the penis.
It is usually the result of sexual stimulation. Rarely, it is due to prostatic disease. Ejaculation may occur spontaneously during sleep known as a nocturnal emission or wet dream. Anejaculation is the condition of being unable to ejaculate. Ejaculation has two phases: emission and ejaculation proper. The pénisz szerkezetének diagramja phase of the ejaculatory reflex is under control of the sympathetic nervous systemwhile the ejaculatory phase is under control of a spinal reflex at the level of the spinal nerves S2—4 via the pudendal nerve.
A refractory period succeeds the ejaculation, and sexual stimulation precedes it.
Vonalak a pénisz tengely, Törpe szalagféreg életciklus diagramja
The purpose of these adaptations pénisz szerkezetének diagramja to maximise reproductive success and minimise sperm competition. Sperm competition is where the sperm of two males simultaneously resides within the reproductive tract of a female and they compete to fertilise the egg. Pénisz szerkezetének diagramja is the process whereby males unwittingly invest their resources into offspring of another Elvesztettem az érzékenységet a péniszemben and, evolutionarily speaking, should be avoided.
As a result, this adaptation also leaves the sperm less vulnerable to sperm displacement and semen loss. Another reason for this adaptation is that, due to the nature of the human posture, gravity creates vulnerability for semen loss. Therefore, a long penis, which places the ejaculate deep in the vaginal tract, could reduce the loss of semen. These varied in height, body shape and flaccid penis size, with these aspects being examples of masculinity.
This is reflected in the association between believed sexual prowess and penis size and the social judgement of penis size in relation to 'manhood'. The human testicles are moderately sized when compared to other animals such as gorillas and chimpanzees, placing somewhere midway.
Human males live largely in monogamous societies like gorillas, and therefore testis size is smaller in comparison to primates in multi-male breeding systems, such as chimpanzees. The reason for the differentiation in testis size is that in order to succeed reproductively in a multi-male breeding system, males must possess the ability to produce several fully fertilising ejaculations one after another.
Ejaculates can travel up to 30—60 centimetres at a time which, when combined with its placement at the highest point of the vaginal tract, acts to pénisz szerkezetének diagramja a male's chances that an egg will be fertilised by his sperm as opposed to a potential rival male's spermthus maximising his paternal certainty.
Size The number of sperm in any given ejaculate varies from one ejaculate to another.
A male will alter the number of sperm he inseminates into a female according to his perceived level of sperm competition,  inseminating a higher number of sperm if he suspects a greater level of competition from other males. In support of ejaculate adjustment, research has shown that a male typically increases the amount he inseminates sperm into his partner after they have been separated for a period of time. Increasing the number of sperm a male inseminates into a female acts to get rid of any rival male's sperm that may be stored within the female, as a result of her potential extra-pair copulations EPCs during this separation.
Through increasing the amount he inseminates his partner following separation, a male increases his chances of paternal certainty. This increase in the number of sperm a male produces in response to sperm competition is not observed for masturbatory ejaculates. Research has pénisz szerkezetének diagramja, for example, that simply viewing a sexually explicit image of a female and two males i. Female phenotypic quality A female's phenotypic quality is a key determinant of a male's ejaculate investment.
Increasing investment in females with high quality phenotypic traits therefore acts to offset the ejaculate investment of others. Through assessing a female's phenotypic quality, males can judge whether or not to invest or invest pénisz szerkezetének diagramja in a particular female, which will influence their subsequent ejaculate adjustment.
Semen displacement The shape of pénisz szerkezetének diagramja human penis is thought to have evolved as a result of sperm competition.
This means that in the event of a rival male's sperm residing within the reproductive tract of a female, the human penis is able to displace the rival sperm, replacing it with his own. Firstly, by displacing a rival male's sperm, the risk of the rival sperm fertilising the egg is reduced, thus minimising the risk of sperm competition. However, males have to ensure they do not displace their own sperm. It is thought that the relatively quick loss of erection after ejaculation, penile hypersensitivity following ejaculation, and the shallower, slower thrusting of the male after ejaculation, prevents this from occurring.
Research pénisz szerkezetének diagramja studied how much semen is displaced by differently shaped artificial genitals. It does this by forcing the semen under the frenulum of the coronal ridge, causing it to collect behind the coronal ridge shaft. It must be combined with adequate thrusting to be successful.
It has been shown that the deeper the thrusting, the larger the semen displacement. No semen displacement occurs with shallow thrusting. Males and females report greater semen displacement pénisz szerkezetének diagramja following allegations pénisz szerkezetének diagramja infidelity. In particular, following allegations of infidelity, males and females report deeper and quicker thrusting during sexual intercourse.
Circumcision causes the coronal ridge to be more pronounced, and it has been hypothesised that this could enhance semen displacement.
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Females report that their vaginal secretions diminish as intercourse with a circumcised male progresses, and that circumcised males thrust more deeply. It can result from fluid trapped in a foreskin left retracted, perhaps following a medical procedure, or accumulation of fluid in the foreskin because of friction during vigorous sexual activity.
In Peyronie's diseaseanomalous scar tissue grows in the soft tissue of the penis, causing curvature. Severe cases can be improved by surgical correction. Pénisz szerkezetének diagramja thrombosis can occur during periods of frequent and prolonged sexual activity, especially fellatio.
It is usually harmless and self-corrects within a few weeks. Infection with the herpes virus can occur after sexual contact with an infected carrier; this may lead to the development of herpes sores.
Pudendal nerve entrapment is a condition characterized by pain mechanikus pénisznövelő sitting and the loss of penile sensation and orgasm.
Occasionally there is a total loss of sensation and orgasm. The pudendal nerve can be damaged by narrow, hard bicycle seats and accidents. This can also occur in the clitoris of females. Penile fracture can occur if the erect penis is bent excessively. A popping or cracking sound and pain is normally associated with this event.
Emergency medical assistance should be obtained as soon as possible. Prompt medical attention lowers the likelihood of permanent penile curvature. In diabetesperipheral neuropathy can cause tingling in the penile skin and possibly reduced or completely absent sensation.
The reduced pénisz szerkezetének diagramja can lead to injuries pénisz szerkezetének diagramja either partner and their absence can make it impossible to have sexual pleasure through stimulation of the penis. Since the problems are caused by permanent nerve damage, preventive treatment through good control of the diabetes is the primary treatment. Some limited recovery may be possible through improved diabetes control. Erectile dysfunction is the inability pénisz szerkezetének diagramja develop and maintain an erection sufficiently firm for satisfactory sexual performance.
Diabetes is a leading cause, as is natural aging. A variety of treatments exist, most notably including the phosphodiesterase type 5 inhibitor drugs such as sildenafil citrate, marketed as Viagrawhich work by vasodilation.
Priapism is a painful and potentially harmful medical condition in which the erect penis does not return to its flaccid state. Priapism lasting over four hours is a medical emergency.
Szalagféreg életciklus- diagramja. Szalagféreg életciklus diagramja - spalettaetterem.hu
The causative mechanisms are poorly understood but involve complex neurological and vascular factors. Potential complications include ischaemiathrombosisand impotence. In serious cases the condition may result in gangrenewhich may result in amputation. However, that is usually only the case if the organ is broke out and injured because of it. The condition has been associated with a variety of drugs including prostaglandin.
Contrary to common knowledge, sildenafil Viagra will not cause it. It tends not to share the common blue tint with a vein however. It can be pénisz szerkezetének diagramja as a hardened lump or "vein" even when the penis is flaccid, and is even more prominent during an erection.
Törpe szalagféreg életciklus diagramja
It is considered a benign physical condition. It is fairly common and can follow a particularly vigorous sexual activity for men, and tends to go away if given pénisz szerkezetének diagramja and more gentle care, for example by use of lubricants.
Pénisz szerkezetének diagramja of the penis is rare with a reported rate of 1 person inin developed pénisz szerkezetének diagramja. Some sources state that circumcision can protect against this disease, but this notion remains controversial among medical circles. Hypospadias can also occur iatrogenically by the downward pressure of an indwelling urethral catheter. A micropenis is a very small penis caused by developmental or congenital problems.
Diphalliaor penile duplication PDis the condition of having two penises.