Sperm and Ova
Sperm and ova are the male and female sex cells respectively
Is the full resulting from the fusion of the sperm and ova
When sperm penetrates the ovum. Zygote contains 23 chromosomes from the mother (ovum) and 23 chromosomes from the father (sperm). The new individual will have 23 pairs of chromosomes (46 chromosomes). Fertilisation usually takes place in the female fallopian tubes. Sperm is deposited in the vagina and swims towards the fallopian tubes.
When the ovum is extracted from a woman's body and fertilised by the sperm outside the body. If a zygote does get produced it is then implants back into the woman's body.
Fertilisation > zygote travels down he fallopian tubes and is constantly dividing > implantation
Implantation starts from day 5 to day 10-12
Between days 3-4 > about 16 cells are present and are constantly dividing, this is called morula
On day 5 > implantation starts and a morula is then called a blastocyst. The inner part of the blastocyst will become the embryo (the baby) and the outer lining will be called the placenta.
Between days 10-12 > implantation stage is complete and the zygote is now called an embryo
Cell differentiation occurs at this stage. Cells start taking on specialist roles e.g.. Heart cells, blood cells, liver cells. This stage is the most crucial part in the 9 months as the foetus is growing and developing organs and the brain. Even though the embryo is only 2 cm many of the body's internal organs, nervous system and circulatory system. Although these things begin to form they are not completed for another 8 weeks. By the 8th week the embryo becomes human looking but the head and neck are half the embryos length and the brain takes up half the body weight. Environmental influences can crucially affect this stage such as tobacco, alcohol and medication can affect the development of the foetus.
This is the 9th week of pregnancy and continues until birth. This is the stage when the baby grows to about 50 cm in length. This characterizes rapid growth and many other developmental milestones. All the organs and systems mature and start to function in the early stages of foetal development. The placenta is fully developed and is functions at about 14 weeks. It is a disc-shaped temporary organ which is made up of blood vessels and exchanges substances between the mother and the foetus. It supplies the baby with oxygen and acts as a liver, lungs and the digestive system. The provides the nutrients the baby needs to growth and develop over the 9 months and allows the excretion of waste. The umbilical cord provide nutrient-rich oxygenated blood from the placenta, they are both connected to the uterus (the mother) and this allows the exchange of nutrients and blood. The placenta also produces hormones to assist in maintaining pregnancy. Even though the sex of the child can be determined during conception, the sex organs will be fully developed and for a female producing eggs and a male will produce testosterone.
Factors that affect the health and development of an unborn child
Behavioural - Vaccinations - Alcohol - Diet\Nutrition - Drugs - Stress levels of parents
- Social economic status - Obstetric care - Smoking - Housing - Access to health care
- Genetics - Chromosomal abnormalities - Disability status of parents\mother
Positive Behavioural Determinants Negative Behavioural Determinants
- Vaccinations - No vaccinations
- High social economic status - Low social economic status
- No alcohol consumption - Alcohol consumption
- Good diet - Poor diet
- No drugs - No obstetic care
- Regular obstetic care - Substance abuse
- No smoking - Smoking regularly
- Good housing - Poor housing
- Good parental health status - Poor parental health status
- Good genetics - Poor genetics