Unit 2 Health & Human Development Sac

The point in time when the sperm fertilises the egg, the genetic material fuses and development begins

0-2 weeks

3-8 weeks

9-40 weeks

Starts at fertilisation and ends with implantation. When fertilised the newly formed cell (zygote) travels down one of the fallopian tubes while constantly dividing, the zygote takes a spherical shape and is now known as a Morula (3 to 4 days after fertilisation -16 cells) . At around 5 days after fertilisation where there is around 64 cells, the morula transforms to include an outer cell mass, an inner cell mass and a hollow, fluid-filled centrecalled the blastocyst cavity. This is then known as the blastocyst. The inner cell mass of the blastocyst will become the embryo and the outer cell mass will become the placenta.
When it reaches the uterus the blastocyst plants iteself into the endometrium, at this point it then becomes known as an embryo.

The embryonic stage starts at implantation and ends at the 8th week. This is where the cells start taking on specialised roles such as heart cells, skin cells, and bone cells.
This is one of the most critical stages as it is when the internal and external organs start forming, and the brain and spinal cord are almost complete by the end of it.

The foetal stages start at the 9th week and continues until birth at around 40 weeks.
All organs and systems formed in the embryonic stage (lungs, digestive system, liver and kidneys) mature and are functioning in the early stages of foetal development. The placenta is fully developed by 14 weeks, made up of blood vessels, that help the transfer of mother and child.
The placenta acts like a kidney, lung and digestive system for the foetus supplying it with oxygen, nutrients and immune support, and removing waste such as urine and carbon dioxide.
Sex organs start taking shape around the 15th week.
Senses begin to function 25 weeks after fertilisation and the foetus may respond to light, sound and touch.
Fat is deposited under the skin during the later weeks of the foetal stage to help assist with temperature regulation after birth.

Anything in the environment of the embryo that can cause defects in development. Examples include tobacco smoke, alcohol, shellfish, prescription medication and some diseases like measles.

Refers to the deaths of babies over 20 weeks old and up to 28 days after birth.

Often referred to as ‘birth defects’, they often occur because of missing or ill-formed body structures. They can be of genetic, environmental or infectious origin, but it often cannot be identified.

Are babies that are born with no signs of life

Are causes of morbidity among unborn children that go undiagnosed until after birth

Gestational diabetes is a form of diabetes that can occur during pregnancy in women who have not previously been diagnosed with diabetes. Like all forms of diabetes, gestational diabetes is characterised by high blood glucose levels.

Pre- eclampsia is a disorder of pregnancy characterised by hypertension, protein in the urine and fluid retention (also known as oedema) leading to swollen hands, feet and face.

An ectopic pregnancy occurs when, instead of implanting in the uterus, the embryo implants elsewhere in the mother reproductive system.