2.1.1-5 Flashcards
steps of fertilisation
ovulation ovum swept into fallopian tube sperm penetrates ovum and tail detaches ovum becomes impenetrable genetic info combined fertilised egg implants in endometrium
what day is ovulation
day 14 of menstrual cycle
germinal stage time
conception - implantation (end week 2)
embryonic stage time
implantation (end week 2) - end week 8
foetal stage time
end week 8 - birth
germinal stage
zygote -> morula -> blastocyst
zygote travels down fallopian tube while constantly dividing to 16 cells
morula after 5 days, 64 cells
transforms into inner and outer mass and hollow centre
blastocyst, inner -> embryo, outer -> placenta
zygote
a fertilised ovum
0-16 cells
morula
solid ball of cells resulting from division of zygote
16-64 cells
blastocyst
inner mass will become embryo and outer mass will become placenta
64 cells
embryonic stage
no period b/c HCG hormone increase means detectable pregnancy
cell differentiation and specialisation
most organs and systems are formed
brain and spinal cord almost complete
placenta and umbilical cord begin to function
embryo sensitive to teratogens
teratogens
anything in the environment of the embryo that can cause defects in development
e.g. tobacco, alcohol, medication
foetal stage
‘foetus’
all organs and systems are formed, mature and are functioning (lungs, digestive system, liver, kidneys)
placenta fully developed
sex identifiable: 15th week
reflexes highly responsive and continue to develop
senses function: 25 weeks
placenta
supplies the foetus with oxygen, nutrients and immune system support
trimesters
first: 1-13
second: 14-27
third: 28-birth
perinatal mortality
relates to the death of babies before birth (over 20 weeks gestation) and up to 28 days after birth
leading causes of perinatal mortality
congenital abnormalities
spontaneous preterm births
unexplained antepartum deaths
congenital abnormalities
birth defects
spontaneous preterm births
relates to births where labour begins without medical intervention between the 20th-37th weeks of pregnancy
organs born prematurely and not fully developed
unexplained antepartum deaths
related to babies who are born with no signs of life
prenatal morbidity
usually goes undiagnosed until birth
leading causes of prenatal morbidity
neural tube defects
down syndrome