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07 A szaporodás és az egyedfejlődés

2014.04.09

Reproduction

 

Humans:

  • Sexual reproduction
  • Separate sexes
  • Internal fertilization

Chromosomes:

  • Male: XY
  • Female:XX

Primary sexual characteristics: genitals

Secondary sexual characteristics: build, hairs, voice…

 

Male sex organs

Testicles

  • Tubular glands
  • Are situated in scrotum (muscular sac outside the body, 2-3oC cooler temperature)
  • Produce sperm cells (meiosis): head (DNA, enzymes), neck (mitochondria), tail (flagellum)
  • Secrete male sex hormone (testosterone)

Epididymis

  • Sperms are stored and matured

Spermatic duct

  • Muscular tubes
  • Transport the sperm cells (peristalsis)

Seminal vesicles

  • Produces alkalic mucus (rich in fructose)

Prostate gland

  • Surrounds the meeting point of spermatic ducts and urethra
  • Produces alkaline thin fluid

Urethra

Penis: copulatory organ

  • Radix
  • Cavernous bodies: spongy tissue filled with blood in case of sexual excitement (erection)
  • Glans: nerve endings
  • Foreskin: protects the glans (oil glands)

 

Female sex organs

Ovaries

  • Plum-shaped organs in the lower abdominal cavity
  • Contain oocytes (immature egg cells): 400,000 oocytes are produced before birth – they are matured after puberty (menstrual cycle: 1 egg cell in 28 days)
  • Secrete female hormones (oestrogen, progesterone)

Fallopian tube (oviduct)

  • Muscular tube with ciliated inner lining, transports the egg cell to the

Uterus

  • Pear-shaped organ with smooth muscle walls
  • It is the place of the development of the foetus
  • Cervix: opening of the uterus, leads to the

Vagina

  • Female copulatory organ
  • Glands produce acidic mucus (rich in lactic acid, protects against germs)
  • Labia minora (lesser lips): protection
  • Clitoris: nerve endings (orgasm)
  • Labia majora (greater lips): protection

 

Female cycle

Follicle: egg cell matures, produces estrogen (womb’s wall develops)

14th day: ovulation

Yellow body: produces progesterone (wall of the uterus thickens)

Menstruation: wall of the uterus sheds with bleeding (28th day)

 

Fertilization

Egg cell: after ovulation lives for 2 days

Sperm cells: can not survive in acidic conditions, about 1000 of 300 million can reach the egg cell

Fertilization: 1 sperm cell head enters the cell membrane of the egg cell – DNA gets in, neck and tail is lost

 

Birth control, contraceptive methods

  • Spermicid gels, balls
  • Interrupted coitus
  • Condom, pessary
  • Contraceptive pills
  • „Morning-after-pills”
  • Rythm method

 

Fetal (embrionic) development

Zygote: mitosis

Morula

Blastocyst

Implantation: fixes on the wall of the uterus (4-7th days)

Chorionic gonadotropin: produced by the embryo (villi of chorion) (maintains the yellow body to secrete progesterone) – detection of pregnacy

Embryo:

  • embryonic nodule – embryonic disc (ectoderm, mesoderm, entoderm)
  • Amniotic cavity, amnion (secretes amniotic fluid)
  • Yolk sac
  • Entoderm: digestive system, respiratory system
  • Mesoderm: bones, muscles, circulatory and excretory system
  • Ectoderm: skin, nervous system

1st month: blood vessels, heart, eye, limbs

2nd month: fingers, nails

Fetus: after 8 weeks

Placenta and umbilical chord: connection between the circulatory system of the fetus and mother (3rd month)

 

Pregnancy and labour

Pregnancy: 280 days

Labour:

  • Regular contractions of the uterus (oxytocin!)
  • Dilatation of cervix
  • Birth: expulsion of the baby (birth canal) and the placenta (10-15 minutes later)

 

Postembrionic (postnatal) development

Newborn: 10 days, decrese in weight, sleeps a lot, fed with breastmilk in every 3 hours

Babyhood: -1 year, walking, urination control, first teeth and first words

Infanthood: -6-7 years, limb elongation, 20 milk teeth (replacement may start)

Childhood: -12 years, more growth, sexual differences appear

Pubescence: -18 years, sexual maturation, menstrual cycle, beard, muostache, intense development, psychical problems

Adolescence: -25 years, grow stops

Adulthood: -60 years, anabolism and catabolism balanced, climax or menopause in women at age of about 50

Old age: -75, catabolism is faster than anabolism, decline

Senescence: till death

 

Disorders and sexually transmitted diseases

Syphilis:

  • Caused by a bacterium
  • 1. Painless red ulcer in the genitals
  • 2. Spots all over the body
  • 3. General paralysis (bones, joints, liver, nervous system is damaged): lethal
  • Treatment: antibiotics

Gonorrhea:

  • Caused by a bacterium
  • Painful urination, pus release

Trichomonas

  • Green-yellow stinky vaginal discharge
  • Painful coitus

Candida

Herpes: painful spot – vesicles - scab

Human Papilloma Virus: warts – cancer of the cervix

Cancer of the ovaries, uterus

Breast cancer

Prostate tumour

Aids acquired immune deficiency syndrome (AIDS):

  • Is caused by the human immunodeficiency virus (HIV)
  • Virus is transmitted by blood, semen, vaginal secretions
  • Transmission factors: sexual contact, infected blood or needles
  • T-lymphocites are blocked
  • Patient dies in pneumonia, cancer or other diseases