Pre-natal development Flashcards
Sex cells
Sperm and ova are the names given to the male and female sex cells
What happens to the sex cells during fertilisation
When sex cells are created, they each contain half of the individuals genetic material which will fuse into one cell called a zygote with a complete set of genetic material during fertilisation.
What is fertilisation?
Fertilisation is when a sperm cell penetrates an egg cell and their genetic material fuses to form one cell.
How long is pregnancy?
Gestation period is 38 weeks however menstrual period is also counted so it is 40 weeks
Where does fertilisation occur?
Fertilisation occurs within the fallopian tubes
Name of cell once sperm and ovum fuse together?
Zygote
Stages and weeks of prenatal development
Germinal (0-2 wks)
Embryonic (3-8wks)
Foetal (9-40 wks)
When does germinal stage begin and end
it begins at fertilisation and ends at implantation into the endometrium
summary of the germinal stage
the zygote divides whilst being gently pushed by cilia into the uterus where implantation occurs
Steps of germinal stage
- sperm penetrates egg
- cell divides for the first time
- now called a morula, is 16 cells large
- blastocyst containing 64 cells consists of an inner and outer compartment
- Blastocyst begins to implant into the endometrium (uterus lining
What is the main characteristic of the embryonic stage?
Development of major organs
Why is the embryo especially sensitive to teratogens?
because the major organs are forming during this stage
What are teratogens
environmental influences such as tobacco or alcohol
what happens during this stage? List 3 things
Any 3 of:
- Cells continue to rapidly divide and cells start taking on specialised roles.
- Tissues that will become brain & spinal cord begin to develop.
- Embryo secretes hormones to prevent mother from having a menstrual period and keep the endometrium maintained.
- Buds appear which will form the limbs, heart begins to beat
- Placenta has begun to develop but will not be functional until in a number of weeks
- Brain cells generated at around 100 per minute
- Spinal cord looks like a tail and head is large in proportion to the rest of the body
- Approximately 1.3 cm long
- Blood cells being made in the liver
- Facial features forming
- Tiny muscles formed
- Fingers & toes beginning to form
- Brain is active
- 2.5 cm in length
What is the foetal stage characterised by?
Rapid growth