Foetal development assessment Flashcards
define fertilisation
Is the fusion of the sperm and ova
define implantation
The process whereby an embryo (blastocyst) sinks into the endometrium
where does fertilisation occur
The fallopian tubes
where does implantation occur
Occurs at the endometrium
define zygote
The fertilised ovum from which a new individual develops
define embryo
The early stage of development of an organism in humans.
define foetus
The developing individual after the second period of pregnancy
Relate a zygote to the stages of development
A zygote goes through many divisions after fertilisation during the cleavage stage. 2 cells - 4 cells - 8 cells - 16 cells. A solid ball of cells will form called a morula. The morula moves down the fallopian tubes and changes to a blastocyst.
describe the embryonic cycle
After the cleavage stage, the blastocyst will embed itself into the endometrium. The embryonic knot will transform into the primary germ cells. The amniotic membrane and yolk sac will form. The germ layer will bend to form a cylinder shape, which causes the amniotic membrane to increase in size and the yolk sac to decrease in size.
define differentiation
The process of stem cells becoming specialised and developing special characteristics to suit their functions
define specialisation
When cells replicate over and over to give rise to specialised cells
what are the three germ layers
- ectoderm
- mesoderm
- endoderm
what is the function of the germ cell
Their function is to differentiate and specilise into different cells
what does the ectoderm form
- skin
- hair
- nervous system
what does the endoderm form
- alimentary canal
- the lining of the lungs
- epithelium of gall bladder
what does the mesoderm form
- bones
- muscles
- blood
what are the different stem cell classifications
- totipotent
- pluripotent
- multipotent
what are stem cells
stem cells are unspecialised. They are capable of repeated divisions by mitosis.
what are totipotent stem cells
form any part of the embryo and surrounding membranes
what are pluripotent stem cells
form any part of the embryo
what are multipotent stem cells
Give rise to cells with a particular function
the foetus development - monthly changes
3 months - - forelimbs develop - bone marrow formed 4 months - - arms and hands fully shaped - skeleton completed 5 months - - fine hairs cover the body - gripping reflexes developed 6 months - - respiratory movement s - eyebrows 7 months - - all systems functional - except respiratory 8 months - - accumulation of fat underneath the skin 9 months - - eyes open - nose well-formed
roles of the placenta and hormones to establish viable pregnancy
The placenta is an organ that supplies nutrients and removes wastes from the foetus. Chorionic villi develop from the chorion membrane and contain blood vessels. As the baby’s chorionic villi penetrate the endometrium, it becomes surrounded by the mother’s blood. The placenta is attached to the foetus via the umbilical cord, which consists of umbilical veins and arteries. The arteries release wastes and CO2 and absorb nutrients and O2 through the veins, all by diffusion and active transport.
the embryo development - structural changes
week 4 -
- development of muscle segments
- brain begins to form
- heart and liver begin to form
week 5 -
- arm and legs begin to form
week 6 -
- all organs are present (not all functional)
- eyes appear like slits
why are cells produced by initial cell divisions totipotent
These cells are totipotent as they must form parts of the embryo and surrounding membranes. Membranes include the amniotic membrane, yolk sac and chorionic membrane.
what is the function of the amniotic fluid
This fluid serves to protect the embryo against physical injury by acting as a shock absorber
how long is the embryonic period
8 weeks
how long is the foetal period
30 weeks
what is the major difference between both embryonic and foetal development
Differentiate greatly in terms of growth. During the embryonic period, the baby grew from 4mm to 3cm. During the foetal period with grows from 3cm to 50cm. The weight increases from4 grams to 3400 grams
what are 4 indications that a woman is pregnant
- Her growing abdomen
- Enlargement of breasts
- Increases heart size + increase in blood volume
- Increase in urine production
