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Classified in Biology

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Stages of reproduction:
The formation of gametes, fertilisation in order to form the zygote, and the development of the embryo.
Ovarian cycle:
Oogenesis occurs regulary in women from puberty onwards, every 28 dys, takes place in 3 stages:
Follicular fase: lasts 14 days
Ovulation: consist of the release of an ovum through the ovary as a consecuence of the production of the hormone LH by the hypophysis
Secretory phase: once the ovum is released, the corresponding area transforms into a mass of cells that produces and secretes the hormone progesterone.
Fertilisation:
Takes place inside the female reproductive system, usually in the fallopian tubes. Every ejaculation, more than 300 million of spermas are expulsed but only one of them would fertalise the ovum. When spermas surround the ovum they secrete certain substances that separate its cells. Next after both gametes recognize each other, the spermas join in the pellucid of the ovum. When the first sperma penetrates the ovums membrane the nuclei of the gametes fuse. It is then when the zygote is formed. Then a protective cover is formed that stops other sperms from coming in.
Contraceptive methods:
There are two groups, natural and artificial:
Natural: 
Basal temperature: this method entails measuring womans temperature giving them after ovulation.
Ogino: observing menstrual cycles for several months calculating when ovulation takes place
Billings method: estimates the approximate time of ovulation by observing changes in the vaginal discharge from de cervix
Sympto.Thermal: combination of the ones before
Coitus interruotus: remove the penis from vagina before ejaculation.



Artificial: barrier, chemical and surgical:
Barrier:
Male condom, female condom, diaphragm (rubber cap at the uterus), UID(cooper and plastic device for intoxicate sperms)
Chemical:
Spermicides (a substance able to destroy sperms), hormone contraceptives (pills for stoping ovulation), morning after pill (high concentration of hormones prevent implantation of the bastula), 5day morning after pill (similar to the one above)
Surgical: 
Tubal ligation (fallopian tubes in female are cutted an joined, this makes female permanently sterilised), vasectomy (the ductus deferens in males are cut and joined in order for sperms not be able to reach the semen.
Diseases:
Hepatitis B: caused by HBV virus, causes fatigue, fever, can cause serious liver damage and cancer.
Genital herpes: caused by the VHS virus, painful blisters on the genitals and sometimes periodically recurring chronic infections.

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