abnormalities of human devleopment

Question 1

causes of maldevelopment

Answer 1

mostly due to many factors, but a third due to genetics

Question 2

identical twins vs chimaerism

Answer 2

one conceptus forms 2 sets of genetically identical cells vs 2 genetically different conceptuses combine to form one person

Question 3

define conceptus

Answer 3

everything that develops from zygote, including embryo

Question 4

what are conjoined twins

Answer 4

where there is only partial separation of inner cell mass

Question 5

what is mosacism (non-disjunction)

Answer 5

chromosomes not distributed evenly

Question 6

distribution of cells in baby and placenta

Answer 6

cells can distribute so that placenta is abnormal, but baby is not

Question 7

eye colour- chromosome, most common colour, and when differentiation ccours

Answer 7

chr15, brown, and day 22, so any abnormality must occur BEFORE day 22

Question 8

kleinfelters- chromsomes and main effect

Answer 8

XXY= less fertility

Question 9

what determines survival in downs

Answer 9

heart issues

Question 10

edwards syndrome- chr and severity

Answer 10

18, very few are born

Question 11

patau’s syndrome- chr and severity and how common

Answer 11

13, most die before- rarest out of the 3

Question 12

turners syndrome, and is YO viable

Answer 12

XO- female, short and infertile- NO

Question 13

any autosomal conditions of too few chromsomes

Answer 13

no ie loss of any autosomal chromsome= certain death

Question 14

XY linked translocation

Answer 14

XX male- where should be girl, but partial translocation of Y chromosome= male

Question 15

autosomal translocation effects

Answer 15

leads to tumours, as chromosomes control cell growth

Question 16

what occurs in holt oram syndrome- mutation and structures affected

Answer 16

mutation in TBX5 T.F= heart (division of atria issue) and hand defects

Question 17

achondroplasia- mutation and effect

Answer 17

FGFR3 mutation (increased function)= less cartilage converted to bone= short limb bones

Question 18

teratogens- define and examples

Answer 18

agents that disrupt development of fetus- infectious agents like HSV/HIV, physical like Xrays, and chemical like alcohol/lithium- heart/CNS/lungs vulnerable earlier

Question 19

polydactyly

Answer 19

extra finger- abnormality occurs at around day 25

Question 20

what factor controls limb development

Answer 20

sonic hedgehog

Question 21

cleft lip/palate- cause and treatment

Answer 21

lip/palate separated, as they form from two separate halves of the face- can be treated easily

Question 22

spina bifida- types

Answer 22

bulge of tissue from spine outside body- contains either only CSF (meningocele) or neural tissue (myelomeningocele)

Question 23

effect of surgery on spina bifida

Answer 23

helps with anatomical issues, but functional issues ie below lesion often can’t be repaired

Question 24

cause of spina bifida including time

Answer 24

spine forms a tube- if tube not sealed ie neurulation, leads to a hole at around day (called neuropore0 21-28=

Question 25

key nutrient decreasing incidence in spina bifida

Answer 25

folic acid- give 3 months before pregnancy (as egg takes 3 months)

Question 26

anencephaly- day and cause

Answer 26

defect in brain development due to formation of anterior neuropore ie at top of spine around day 22

Question 27

thalidomide- structures affected and cause including day

Answer 27

causes deformed limbs (especially upper)/eyes and heart- affects blood vessels, thus cells of limb bud die= limbs affected- day 28

Question 28

use of thalidomide

Answer 28

still used in leprosy+ cancer (as blood vessels affected)

Question 29

respiratory distress syndrome- effect and treatment

Answer 29

babies has no lung surfactant (develops in last trimeser)= lungs can’t expand: injection of glucocorticoids

Question 30

facial devleopment

Answer 30

facial structures develop on side of head, then move to middle-