prenatal development

Question 1

germinal stage

Answer 1

0-2 weeks
starts at fertilisation and ends with implantation
when fertilised, the zygote travels down one of the fallopian tubes while constantly dividing
once implantation begins the placenta starts to perform

Question 2

germinal - 1 day

Answer 2

the zygote divides as it travels down the fallopian tubes

Question 3

germinal - 4 days

Answer 3

zygote contains around 6 cells (now called a MORULA)

Question 4

germinal - 5 days

Answer 4

morula now has 64 cells and turns into a BLASTOCYST
inner mass of the blastocyst will become the embryo
outer cell will become the placenta

Question 5

germinal - 7-12 days

Answer 5

once it reaches the uterus the blastocyst implants itself in the endometrium
becomes an EMBRYO

Question 6

embryonic stage

Answer 6

3-8 weeks
starts at implantation and ends at the 8th week
characterised by cell differentiation

Question 7

cell differentiation

Answer 7

when cells start taking on specialised roles such as heart cells, skin cells and bone cells

Question 8

characteristics of embryonic stage

Answer 8

• lasts from implantation until the end of week 8
• specific cells start taking on their specialised roles
• most critical stage for human development
• many internal and external organs and systems are formed, and by the end a spinal chord and brain develops
• TERATOGNES (alcohol, tobacco, medications) pose significant risk in this phase
• gender is determined, but sex organs will not complete growth until the foetal stage
• PROCIMODISTAL stage, limbs start out as buds growing from the torso and continue to develop
• embryo becomes human looking
• head and neck account for half the embryos total length
• brain makes up almost half its body weight

Question 9

foetal stage

Answer 9

9-38 weeks
starts at the 9th week of pregnancy and continues until birth at around 38 weeks
baby is referred to as a foetus

Question 10

characteristics of foetal stage

Answer 10

• longest of all prenatal phases
• massive growth, including the development of organs and body systems
• all muscles, organs and nerves begin to function
• kidneys, liver, lungs all work to filter blood
• lungs are filled with amniotic fluid
• placenta is formed and functioning at this stage