Congenital defects and human embryology Flashcards
what is the leading cause of infant mortlality? [1]
birth defects
what can cause congenital defects? [3]
About 70% of all birth defects have an unknown cause or it is multifactorial
13-15% of congenital defects are chromosomal: i.e. down syndrome is usually trisomy of chromosome 21
medication that cause congenital defects (e.g. thalidomide)
Environmental agents: infectious agents (Zika, rubella, CMV), chemical agents, alcohol (leading cause of birth defects in W. world)
what is spina bifida? [1]
what is it caused by? [1]
how do you prevent it? [1]
what is spina bifida? [1]
Spina bifida is when a baby’s spine and spinal cord does not develop properly in the womb, causing a gap in the spine
what is it caused by? [1]
lack of folic acid
how do you prevent it? [1]
take folic acid 3 months before pregnancy
which congential defects are increasing? [2]
give a reason for each? [2]
: 1. gastroschisis (cigarette smoke)
- Downs syndrome (due to maternal age increasing)
apart from spnda bifida, what does a diet with folic acid reduce the possibility of? [2]
explain the physiology of why folic acid is important x [1]
how much does a pregnant person need? [1]
apart from spnda bifida, what does a diet with folic acid reduce the possibility of? [2]
- *cleft lip and palate**
- *pre-eclampsia**
explain the physiology of why folic acid is important x [1]
Folic acid gets metabolised to folate –> involved in DNA synthesis
how much does a pregnant person need? [1]
need 400 microrams daily
how much vit D should preg. person take? [1]
10 micrograms a day
at what stage during development are you at highest risk of developing a congenital defect?
explain your answer [2]
At 5 weeks of age you are 4mm, and this is the limit of diffusion. 5 weeks is the peak risk of congenital defects
In embryonic period: most of the organ systems develop (apart from the lungs). It’s the critical period for the development of these structures
during developement
when is the embryonic period?
when is the foetal period?
during developement
when is the embryonic period: 3-8 weeks
when is the foetal period: 8-38 weeks
what is the difference between major and minor congenital malformation?
main differentiator is that major congential defects require surgery to rectify
what is Anencephaly [1]
what is Hypospadia [1]
Anencephaly
major congenital defect where there is absence of a major portion of the brain, skull and scalp and occurs during embryonic development.
You are left with a brainstem so you can survive due to basic reflexes in this brainstem so they can live a couple of years.
Hypospadia:
is when the penis hasn’t fully fused and the urethra opens externally, and sometimes the hole at the tip may be larged and unfused or found in areas not in the middle
Hypospadia is major as it needs surgical intervention to close it up, but it isn’t life threatening.
what is cryptorchidism [1]
(undescended testis) affects 1-4% of live male births yet spontaneously correct within 3 months. If it is still undescended at 1 year of age it will increase the changes of testicular malignancies. Can increase risk of developing testicular cancer
give an example of where the severity of the same defect can vary
Holoprosencephaly severity can be mild to severe and cause can be genetic or environmental (alcohol consumption). This is a loss of the midline structures down the centre of the body.
what is Congenital diaphragmatic hernia?
This is where the diaphragm, separating the thorax and abdomen, doesn’t close so loops of the intestine can come into the thorax, and this can restrict the development of the lungs
what is Gastroschisis
Gastroschisis, when the ant abdominal wall is open, and loops of intestine forming can come out. They are exposed to the physical trauma of rubbing against uterine wall so they become inflamed.
which of the following is the cytotrophoblast?
A
B
C
which of the following is the cytotrophoblast?
A
B
C
which of the following is the will develop into a blastocyst?
A
B
C
which of the following is the will develop into a blastocyst?
A
B
C
which of the following is the syncytiotrophoblasts ?
A
B
C
which of the following is the syncytiotrophoblasts ?
A
B
C
which of the following is the will develop into a blastocyst?
A
B
C
which of the following is the will develop into a blastocyst?
A
B
C
what do inner cell masses of blastocyts differentiate into?
into epiblasts dorsally and hypoblasts ventrally
primary yolk sac is below
which of the following is the primitive streak
A
B
C
D
which of the following is the primitive streak
A
B
C
D
which of the following is the endoderm
A
B
C
D
which of the following is the endoderm
A
B
C
D
which of the following is the mesoderm
A
B
C
D
which of the following is the mesoderm
A
B
C
D
which of the following is the epiblast
A
B
C
D
which of the following is the ectoderm
A
B
C
D
