Reproduction, Fertility and Contraception

Contraception
1. Mechanical
  1. Condom
    1. Acts as a barrier to prevent sperm entering the woman
      1. Easily obtained and also protects against STD's
      2. Unreliable if not used properly
2. Chemical
  1. Contraceptive pill
    1. Taken regularly by the woman and prevents the ovaries from releasing eggs by changing hormone levels
      1. Very reliable
      2. Side effects like weight gain and can increase the risk of blood clots
3. Surgical
  1. Vasectomy
    1. Cutting of sperm tubes preventing sperm from entering penis
  2. Female sterilisation
    1. Cutting of the oviduct preventing the ova from moving through the oviduct and being fertilised
      1. Irreversible
      2. !00% reliable
4. Natural
  1. Avoid having sex around the time when the woman releases an ovum each month
The sperm and eggs
1. Sperm is much smaller than the egg and has the adaption of a tail for ease of mobility new sperm is produced continually, the eggs are in the female system from birth but aren't released until puberty
2. These gametes are formed by meosis
  1. The gametes have the haploid number (23 chromosomes)
3. Sperm is the male sex cell it is produced in the testes
  1. Sperm is produced under the influence of the hormone testosterone
4. Eggs the female sex cell are produced in the ovaries
  1. Eggs are produced under the influence of oestrogen
Fertilisation, pregnancy & development of the baby
1. The production of new living organisms by combining genetic information from two individuals of different sexes
2. The sperm and eggs meet and fuse in an oviduct, restoring the diploid number. the fertilized egg becomes the first cell
  1. This cell then divides by mitosis and grows into a ball of cells as it travels down the oviduct, the ball of cells becomes an embryo which implants itself into the wall of the uterus
    1. The uterus develops a thick lining that holds and nourishes the embryo. The placenta and umbilical cord also form. A protective membrane, the amniotic sac, it contains amniotic fluid, within which the growing embryo develops. This cushions the delicate developing embryo
3. The baby cannot breathe in the amniotic fluid so during pregnancy useful materials like oxygen and glucose pass from the mother. Waste excretory materials pass from the foetus back to the mother
  1. 1. The boundary between maternal blood and foetal blood
      1. The systems are not joined but are close together and separated by thin membranes to allow diffusion of gases and nutrients. the large surface area between the uterus wall and the placenta helps diffusion of materials between mother and foetus
    2. Umbilical cord
      1. umbilical artery: carries urea, carbon dioxide and other wastes back to the mother
      2. umbilical vein: carries oxygen, glucose, amino acids and other nutrients from the mother to the foetus
    3. Placenta
      1. Very rich in maternal blood vessels; mother's blood is rich in oxygen and other nutruents
Puberty
1. Males
  1. Facial and body hair
  2. Pubic hair grows
  3. Body becomes more muscular
  4. Voice deepens
  5. Genitals enlarge
  6. Sexual awareness and drive increase
2. Females
  1. Pubic hair gorws
  2. Hair grows in armpits
  3. Sexual organs enlarge
  4. Breasts develop
  5. Pelvis and hips widen
  6. Menstruation begins
  7. Sexual awareness and drive increase
Menstruation
1. Occurs in females from puberty until the end of reproductive life, the purpose of the menstrual cycle is to prepare the reproductive system for pregnancy by controlling the monthly release of an egg and renewing and replacing the uterine lining.
  1. The cycle is controlled by female hormones. the cycle is usually 28 days long. the cycle begins with menstruation days 1-5, this is when the blood-rich uterine lining breaks down and is passed out of the body.
    1. The uterine lining repairs itself & builds up again in preparation for if implantation occurs days 6-13
      1. Day 14 is ovulation - an egg is released, by this time the lining has been fully repaired and ready for pregnancy, if implantation and pregnancy occur an embryo will start to develop and a placenta forms, if not the uterine wall continues to thicken until day 28
Fertility Problems
1. Treatments
  1. Fertility Drugs
    1. These are given to the woman to increase the production of eggs
  2. In vitro fertilisation
    1. The woman is given fertility drugs and eggs are then collected from her ovaries surgically. sperm is donated and the sperm and the eggs are mixed in the laboratory. successful embryos are placed into the mother's uterus in hope that the embryo will implant itself in to the uterine lining
2. Reasons for fertility problems
  1. Failure of ovary to produce eggs
  2. Oviducts may be blocked/twisted
  3. STD's
  4. Uterus lining doesn't form
  5. Vagina hostile to sperm
  6. Low sperm count / unhealthy sperm
  7. Impotence / erectile disfunction

Medienanhänge

2e35e6cf-3756-4a57-9a16-d0e2b4a0fce6 (image/png)

Nächster

Reproduction, Fertility and Contraception

Beschreibung

Zusammenfassung der Ressource

Medienanhänge

ähnlicher Inhalt

	Erstellt von Rebecca McNaughton vor mehr als 9 Jahre