Embryonic development and PregnancyAnother term for pregnancy is the gestation

period

It lasts for about 280 days which is slightly more than 9 months

Embryonic development and PregnancyEmbryo increases in shape and size as it

grows

By 12 weeks the embryo has grown quite a lot, and will look clearly like a human baby

It is now called the foetus

Development of the extra-embryonic membranes

Soon after the blastocyst itself to the uterus wall, 2 membranes develop around it

Extra-embryonic membranes

Development of the extra-embryonic membranesThese membranes are:The chronian on the outside, forms

chronic villiAn amnion, on the inside, with amniotic

cavity filled with amniotic fluid

Development of the extra-embryonic membranesChronic villi with uterine tissue make up the placentaA hollow rope-like tube called umbilical cord,

attaches the embryo to the placenta

Development of the extra-embryonic membranes

The placenta has the following functions:Attachment of embryo to motherDiffusion of desolved food from mother to

foetus

Development of the extra-embryonic membranesDiffusion of oxygen from mother to foetus

and carbon dioxide from foetus to mother

Development of the extra-embryonic membranesAfter 12 weeks of pregnancy it secretes its

own progesterone which maintains pregnany

Development of the extra-embryonic membranesThe amniotic fluid has the following

functions:

Shock absorber

Prevents dehydration

Development of the extra-embryonic membranesKeeps foetus within a small temperature

range

Allows free foetal movement for growth and development

Development of the extra-embryonic membranesThe umbilical cord contains the umbilical

artery and veinThe artery carries deoxygenated blood

with nitrogenous wastes from the embryo to the placenta

The vein carries oxygenated blood and food

BirthOccurs about 280 days after fertilisation, this

happens in 3 stagesStage 1: Uterus contractsHead pushed against cervixMembranes breakCervix dilates

BirthStage 2:Baby forced out through birth canalUmbilical cord cutBaby handed to mother

Stage3:Placenta becomes loosePlacenta pushed out as the ”after-birth

ContraceptionMethod Description

Natural Methods

Withdrawal The penis is removed out of the vagina before ejaculation but it is not safe method because many sperms are released during sexual intercourse

Rhythm method

Sexual intercourse is avoided during ovulation. This is not a safe method of contraception because it is impossible to be 100 % sure when ovulation will occur

ContraceptionMethod Description

Barrier methods

Condom Act as a barrier to stop sperms from entering the vagina

Femidom Act as a barrier to stop sperms from getting into the uterus/Fallopian tubes

IUD/loop It prevents fertilised eggs/embryos from becoming attached to the uterine wall and is highly effective

Diaphragm It covers the cervical opening and prevents sperm from entering the uterus and is fairly effective

ContraceptionMethod Description

Chemical/drug treatment

Spermicides It contains a chemical substance that kills sperm and acts as a barrier/prevents sperm from entering the Fallopian tubes. They are not very reliable on their own.

Contraceptive pills

Contains artificially produced hormones which prevents the production of eggs/ovulation. Signalling the body that it is already pregnant. It changes the lining of the cervix/womb. It is a very reliable method.

Contraceptive injections

It contains progesterone/combination of oestrogen and progesterone which stops ovulation/changes the lining of the womv and the cervix. It works for 2 to 3 months and are very effective.

ContraceptionMethod Description

Surgical methods

Male Sterilisation

The sperm ducts are cut and tied. Semen without sperm is produced and is a very effective method of contraception.

Female Sterilisation

The Fallopian tubes are cut and tied during a small surgical operation preventing the fusion of sperm and egg

syphilisCaused by spiral bacterium, treponema

pallidumTransmission:Sex with infected partner, mother to child

Symptoms:Nodules on sex organsRash over the bodySore throat and aching muscles

syphilisCan attack tissue or organ including skinLead to blindness and deathTreatment:Antibiotics in early stages

gonorrhoeaCauses:Coccus bacterium, gonococus

Transmission:Sex with infected person

Symptoms:Frequent and painful urination, dischargeSterility in men and woman

gonorrhoeaTreatment:

Antibiotics, penicillin

More difficult to cure in late stages

Prevention of stdsMost stds are life-threateningFor many of them, there is no cureMedication, nutritious diet and healthy lifestyle

can slow down progress of the diseaseUse A B C methodAbstain from sexual activitesBe faithful to your partnerCondomise