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Posted on May 5, 2022 in History
1. REPRODUCTION AND SEXUALITY
The birth of new ndividuals. Reproduction is a key function.
2 characteristics
·the new individual iis formed from a single cell, called a zygote.
· a zygote originates from the union (fertilisation) of two gametes or sex cells.
male and female reproductive system are different, they bothhave gonads.
humans have two kinds of gametes: sperm and ova.
1.becomes an adult able to produce gametes.
2.internal fertilisation. takes place inside the female reproductive system
3.the development of the embryo takes place inside the mother’s body (viviparous)
4.during sexual reproduction, genetic information from both parents is united. new being will not be identical to their parents.
2. CHANGES DURING OUR REPRODUCTIVE LIFE
Stages of reproductive life: puberty, adolescence and the end of the reproductive life.
2.1 puberty
Begins in men with the first ejaculation (spermache) and in women when the first menstruation takes place (menarche). follicle stimulating hormone (FSH) and luteinizing hormone) (LH), stimulate the production of gametes. Hormone secretion produces anatomical, physiological and een psychological changes that transform the boy or girl into an adolescent.
2.2 Adolescence
Physical and psychological changes. develop their sexuality and makes them capable of reproducing. in women, hormones (Estrogen and progesterone) from the ovaries. n men release of sperm and sexual hormones (testosterone) in the testicles. Physical changes increase in size of the sexual organs. pubic and armpit hair beginns to grow, men also develop facial hair. Breasts develop and their pelvses widen, whilst men’s pelvises narrow and shoulders broaden. Larynx and vocal cordsd of men thicken.
2.3 the end of reproductive life
ovaries normally stop functioning completely when women reach 50 years of age, the activity of men’s testicles decreases from that age onwards. physical and psychological changes that are known as the menopause (for women) and the andropause (for men)
3.1 THE MALE REPRODUCTIVE SYSTEM
Is formed by the testicles, penis, reproductive tract and the male accessory glands.
3.1.1 the testicles
Are the organs that produce male gametes or sperm. seminiferous tubes are the cells that produces sperm, male sexual hormones (androgens). testicles are covered by a layer of skin known as scotum.
3.1.2 the reproductive tract
·Epididymis: formed by the seminiferous tubes in each testicles.
·ductus deferens: used to store sperm that remain there until they exit the body.
·urethra: connecting the bladder to the exterior. release of sperm and urine.
3.1.3 the penis
the penis is the male copulatory organ. Deposit the sperm.
3.1.4 Accessory glands
·Seminal vesicles: Secrete spermatic fluid containing glucose, a nutrient for sperm.
·Prostate: Secretes prostatic fluid which consists of substances to protect sperm from the acidity of the vagina.
·Cowper glands: Secrete a lubricating fluid that facilitates sexual intercourse.
3.2 THE FEMALE REPRODUCTIVE SYSTEM
Is formed by the ovaries and reproductive tracts: the fallopian tubes, the uterus, the vagina and the vulva.
3.2.1 The ovaries
Gonads of the female reproductive system are the ovaries. Female gametes or ova are poduced in the ovaries.
Ovaries produce female sex hormones, estrogen and progesterone, essential for adequate sexual development and reproductive ability.
3.2.2 Reproductive tract
·Fallopian tubes: These tubes collect the ovum released by the ovaries and it is here where fertilisation normally occurs.
·Uterus: Lower part, called the cervx. The gestation of a new human being takes place in the uterus.
·Vagina: It secrete lubricating substances. Sperm are placed inside the vagina during sexual intercourse.
·Vulva: Female external genital organ.
4. STAGES OF REPRODUCTION
4.1 Gametogenesis
Ther formation of ova is known as oogenesis and the formation of spermatozoids is known as spermatogenesis.
| spermatogenesis | oogenesis |
|---|
| seminifereous tubes in the testicles | follicles of the ovaries |
| spermatogonia | oogonia |
| starts during puberty and continues for the rest of life | restarts during puberty, and ends every 28 days until the menopause occurs. it takes about 14 days |
| Four sperm from every spermatogonium | one ovum from each oogonium |
4.1.1 Ovarian cycle
It purpose each time is the formation, maturation and release of an ovum.
·Follicular phase: Hormone that stimulates the follicle (SHF). SHF stimulates the ·development of one or several follicles.
·Ovulation: Release of an ovum through the ovary. LH
·Secretory phase: Once the ovum is released, that produces and secretes the hormone progesterone.
4.1.2 Uterine or menstrual cycle
Its purpose is to prepare the uterus to host the embryo in case the ovum is fertilised.
·The menstrual phase or period: Decrease of the ovary’s hormonal secretions, thick mucus of the uterus breaks off and is released to the exterior along with blood from the blood vessels.
·Proliferation phase: Uterine mucus is reconstructed thanks to the action of the estrogens produced by the ovaries.
·Secretory phase: The uterus reaches its maximum thickness and is prepared to host and feed the fertilised ovum.
4.2 Fertilisation
Fertilisation takes place inside the female reproductive system. When the first sperm penetrates the ovum’s membrane, gametes fuse.. Zygote forms.
4.3 GESTATION AND BIRTH
4.3.1 Gestation
The zygote after seven days it arrives at the uterus and joins with the endometrium.
Gestation refers to the time that occurs between fertilisation and birth.
During the first weeks, the cell mass, embryo. When the embryo develops a human shape it is known as the fetus.The development of the embryo has 3 stages:
·germinal: After a series of divisions the zygote transforms into a cell mass known as morula, becomes hollow and creates another structue known as blastula.
·Embryonic: 3 layers of cells are formed from the blastula: the inner layer (endoderm), a middle layer (mesoderm) and an outer layer (ectoderm).
·Fetal: All body structures are formed and the embryo becomes a fetus.
The embryo develops in the interior of a membrane known as amnion, fills up with amniotic fluid that protects the fetus from bumps and external pressures. The embryo feeds through the placenta. The fetus is separated from the uterine lining and is attached to the placenta through the umbilical cord.
4.3.2 Birth
·Dilatation of the cervix: The cervix cells dilates, the myometrium experiences a series of contractions, pushing the fetus towards the vagina. Oxytocin ir responsible for these uterine movements. Amnion ruptures, releasing the amniotic fluid. This is known as breaking water.
·Fetus release: The fetus pushes its head out first, if this does not happen the birth, the fetus is extracted through a caesarean section.
·Delivery of the placenta: After the baby is born, the uterus suffers more contractions in order to release the placenta and umbilical cord. The birth ends.
The first days after birth, the breasts of the mother produce a very nutritious liquid called colostrum. Rich in antibodies. Third day onwards the mother starts to rpoduce breast milk.
·Fraternal twins: Two ova that are fertilised by two different sperm. Double ovulation occurs. Sexes can be different and not look any more alike than brothers or sisters from different pregnancies do.
·Identical twins: Single zygote, has divided itself into two cells. Are genetically identical indiciduals. Same sex and possess similar characteristics.
5.1 Natural contraceptive methods
· Basal temperature: Measuring the body temperature of the woman, given that after ovulation (and during the next few days) it increases by 0.2ºC and 0.5ºC.
· Ogino: Involves observing menstrual cycles for several months and then calculating the approximate day that ovulation will take place.
· Billings method: Estimates the apoximate time of ovulation by observing changes in the vaginal discharge from the cervix.
· Symptothermal: Combination of the ones described above: basal temperature is measured, cervical mucus is observed and the fertile days are then calculated.
· Coitus interruptus: Removing the penis from the vagina before ejaculation happens in order to avoid semen penetrating it.
5.2 Artificial contraceptive methods
5.2.1 Barrier contraceptive methods
Stop sperm reaching the ovum.
· Mal condom: Placed on the erect penis. It collects ejaculated semen.
·Female condom: Place inside the vagina and stops sperm from reaching the uterus.
· Diaphragm: Rubber cap that is placed at the entrance of the uterus in order to stop sperm.
· IUD: A plastic and copper device place in the uterus to stop the implantation of the blastula.
5.2.2 Chemical contraceptive methods
· Spermicides: Applied to the vagina, are able to destroy sperm.
· Hormone contraceptives: Female sexual hormones are incorporated in order to alter the ovarian cycle and stop ovulation.
· Morning-after pill: High concentration of hormones, prevent implantation of the blastula in the lining of the uterus.
· 5-day morning-after pill: Prevents the nesting of the ovum and alters the endometrium.
5.2.3 Surgical contraceptives methods
· Tubal ligation: Fallopian tubes in females are cut and joined to prevent the ovum from reaching the uterus
· Vasectomy: Ductus deferens in males are cut and joined in order for sperm not to be able to reach the semen.
7.1 Healthy reproductive system and sexuality
· Accept and value yourself. Avoid feeling guilty or embarrassed about your body.
· Respect everybody sexual orientation.
· Research the symptoms and consequences of sexually transmitted diseases. Visit a professional medical cente if necessary.
· Use condoms. Avoid having sexual relationships without a condom, especially if you suffer from sexually-transmitted disease.
| Syphilis | Bacterium Treponema pallidum. Damage to the nervous and ciculatory system |
|---|
| gonorrhea | Bacterium Neisseria gonorrhoeae. Infertility and blindness in a newborn |
| AIDS | HIV. Reduction in defence against microorganisms, infections and tumours |
| Hepatitis B | HBV virus. Serious liver damage and cancer |
| Genital herpes | VHS viruss, painful blisters |
| Genital warts | Human papillomavirus (HPV). Warts on the genitals. Cancer in this area |
| Vaginal yeast | Fungus Candida albicans, intense itching. |
| Trichomoniasis | Protozoan Trichomonas vaginalis. Abnormal vaginal discharge and pain |
