Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Year 2 - LCRS - RDA > Development (21.02.2020) > Flashcards

Development (21.02.2020) Flashcards

1
Q

What are the causes of Mal-development?

A

Genetic – 30%

Environmental – 15%

Multifactorial – 55%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are some ‘common’ Mal-developments?

A
  • trisomy 13 (patau)
  • trisomy 18 (Edward)
  • cleft lip
  • eye mosaic (heterochromia)
  • chimerism
  • additional finger
  • thalidomide?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Multiple pregnancies - what are the different types?

A
  • Identical twins / triplets: one conceptus forms 2 / 3 inner cells masses to form 2 / 3 genetically identical individuals
  • Chimerism: 2 genetically distinct conceptuses combine to form one individual
  • Changes in the numbers of conceptuses or fetuses that develop (very early in development)
  • Twins
  • Triplets
  • Chimaera (2 genetically different patterns in one human)
  • conjoined twins (incomplete inner cell mass separation) - the extent of conjointment determines future

=> very gross changes in development

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Conjoined twins

A
  • incomplete inner cell mass separation

- the extent of conjointment and how much shared tissue there is and what the tissue is determines survival

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Cells and chromosomes + cellular distributions

A
  • The distribution of cells and chromosomes can change development.
  • Changes to chromosomes can affect gene expression.
  • Mosaicism (non disjunction) – differences between cells within one individual (e.g. different eye colours)
  • Distribution of cells between inner cell mass & trophectoderm (placenta)
  • Chimerism - fused multiple zygotes
    Non-identical zygotes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Mocaisism

A

(non disjunction) – differences between cells within one individual

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Eye colour

A
  • Human chromosome 15.
  • Brown most common colour; others mostly in Caucasians.
  • Differentiation of eyes begins about Day 22 PF.
  • Event that changes something must predate Day 22.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the most common eye colour?

A

brown

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the possible chromosomal problems?

A
  • Too many, too few, translocations.
  • ALL give rise to syndromes
  • Cross-talk between systems
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

changes in chromosome numbers - too many

A
  • XY linked
  • Kleinfelter’s syndrome (XXY). Decreased fertility
  • XXYY, XXXY, XXXYY, etc – severe forms related to KS
  • XYY (XYYY) – very variable (taller, learning problems)
  • XXX. Limited effects, some mental changes -> this has something to do with X-inactivation (a single X chromosome is inactivated)
  • XXXX, XXXXX. More severe effects
  • in females one X chromosomes is inactivated, in males the other X chromosomes may still have effects

Autosomal

  • Down’s syndrome (ch21) (1 / 1000 live births)
    - Heart problems determine survival.
  • Edward’s syndrome (ch18) (1 / 6000 live births)
    • Most die before birth, very few live-born, live ≤2 weeks.

Patau’s syndrome (ch13) (1 / 15,000 live births)
- Most die before birth, 80% live-born die within 1 year.

  • Others not found in live birth, most detected in some spontaneous pregnancy loss tissues.
  • Ch1 trisomy not found in pregnancy loss tissues, lost pretty much immediately after fertilisation in trisomy.
  • Mosaic or partial extra chromosomal material
  • Less severe symptoms than in complete trisomies.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Chromosomal problems - too few

A

XY linked

  • Turner’s syndrome - X0. Female, short stature, infertile
  • Y0 not viable!!!

Autosomal

  • No complete losses are viable
  • Partial chromosome loss syndromes known and characterised
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Chromosomal problems - altered distributions / translocations

A

XY linked
- “XX male” – XY translocation

Autosomal
- Linked with development of tumours; lymphoma; leukaemia; sarcoma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Function of gene product problems

A
  • Mutations
  • Altered expression
  • Many genes are found in both animals and humans.
  • some gene problems can have very limited effects.Others can have a range of problems (e.g. holt-oram syndrome causing hand and heart defects)/
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Holt-Oram syndrome - heart/hand defects

A
  • Phenotype due to mutation in TBX5 (transcription factor) – required as both structures develop.
  • Atrial septation defects
  • Range of hand abnormalities
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Achondroplasia

A
  • Gain of function mutation in FGFR3
  • constantly active in achondroplasia?
  • Achondroplasia means “lack of cartilage”
  • Defect is in conversion of cartilage to bone & lack of bone growth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are birth defects?

A
  • Birth defect = congenital malformation = congenital abnormality
  • Changes in the PATTERN of development
  • Teratology or dysmorphology
  • Major abnormalities ~3% of pregnancies (cause 25% of infant deaths.
  • Minor abnormalities ~15% (little health impact)
17
Q

What are teratogens?

A

Any agent that can disturb the development of an embryo or foetus

  • most vulnerable in the 1st trimester when tissues are dividing fast
  • some tissues are vulnerable for longer or at a later stage
18
Q

What are teratogen classes?

A

Infectious agents
physical agents
chemical agents

19
Q

List some infectious agents that are teratogens.

A

Rubella virus - Cataracts, glaucoma, heart defects, deafness, teeth
Herpes simplex virus - Microphthalmia, microcephaly, retinal dysplasia
HIV - Microcephaly, growth restriction
Syphilis - Mental retardation, deafness
Zika virus – microcephaly

flu?

20
Q

List some physical agents that are teratogens.

A

X-rays & other ionising radiation - Microcephaly, spina bifida, cleft palate, limb defects

21
Q

List some chemical agents that are teratogens.

A

Thalidomide - Limb defects, heart malformations
Lithium - Heart malformations
Amphetamines - Cleft lip and palate, heart defects
Cocaine - Growth restriction, microcephaly, behavioral abnormalities
Alcohol - Fetal alcohol syndrome, maxillary hypoplasia, heart defects

22
Q

Systems to consider in development

A 
Limbs and digits (e.g. polydactyly)
Urogenital
Heart
Central nervous system (spine and head) (e.g. spina bifida)
Face (e.g. cleft lip)
Lungs
23
Q

Limb development

A
  • Forelimb bud appears at d27/8
  • Hindlimb bud at d29
  • Grow out from lateral plate mesoderm rapidly under control of special signalling regions
  • Fully formed and patterned by d56.
  • day 35 hand plate is formed
  • day 44 5 digital rays

possible mal-developlent: polydactyly

sonic hedgehog (shh) controls the limb development

Rotation in limb development

24
Q

Development of the face

A
  • We start with our eyes on the side (like birds and fish)
  • there is controlled breakdown of tissue in the middle
  • gradual formation of face
  • If the clefts are not filled properly you get cleft palate.
  • surgical repair heals very well if done early, very good repair
25
Q

Spina bifida

A
  • can be due to folate deficiency
  • cause early in pregnancy, sealing up of the tube imperfect around days 22-28 gives rise to spina bifida (there is a neuropore)
  • 1-2 per 1000 pregnancies
  • usually occurs at the base of the spine, can also be in multiple places
  • bulge of tissue
  • it may just be CSF but it may also contain neural tissue
    Neural tissue controls the development of the vertebrae above the spinal cord
  • Surgery can help anatomical, but not functional

Summary
- It is variable, but can be severely disabling
- The primary problem is failure to complete neurulation (posterior neuropore)
- The problem is present within 4 weeks of fertilisation
problems

26
Q

When should folate be given?

A
  • around 3 months before conception or more (because the early conceptus has nutrients and energy supplies from the egg)
  • however it would be good to have sufficient folate in your daily diet
27
Q

Anencephaly

A
  • Defect in skull and brain development
  • Incidence: 1 – 8 per 10,000 births
  • Female babies affected more commonly than male
  • usually brainstem is okay
  • top of the spine has not closed (anterior neuropore has not closed)
  • Folic acid (given at the right time) may show benefit
  • Implies similar causes to spina bifida
  • Anterior neuropore closure incomplete
28
Q

Thalidomide

A
  • drug for morning sickness - taken by women in 1st trimester of pregnancy in the 1960s
  • ~10,000 affected infants known, ~50% initial survival rate.
    Limbs affected.
  • In addition, deformed eyes and hearts, deformed alimentary and urinary tracts, blindness and deafness.
  • Used in some leprosy and cancer treatments at present.
  • interferes with BV development in the developing limb.
    • prolonged exposure leading to widespread cell death and all signalling cells are lost
    • phocomelia: shoer exposure leading to uniform cell death and only partial loss of AER signalling which recovers
  • Thalidomide – affects rapidly developing blood vessels, notably those of upper limbs
  • variable impact
  • Blood vessel affects can be generic, hence the range of effects observed. -> cancer treatment
29
Q

Respiratory distress syndrome

A 
- Overall incidence ~1% of all births
     ~100% at GA 24 weeks
     ~50% at GA 26-28 weeks
     ~25% at GA 30-31 weeks
- high surface tension, lungs won't expand properly (because not enough surfactant)
- inject steroids
30
Q

What is pre-implantation development?

A
  • normally occurs within the Fallopian tube (oviduct) over a period of ~6 days
  • characterised by a series of cleavage divisions, which to produce a ball of undifferentiated cells (the Morula).
  • The Morula differentiates so that the inner cells differ from those on the outside
  • This then develops into the Blastocyst, a structure that has an outer layer of trophectoderm, an inner cell mass, and a fluid-filled cavity.
31
Q

Implantation

A
  • after preimplantation the Blastocyst hatches from the Zona Pellucida (within which it has developed up to this time, about day 6 PF),
  • begins to implant in the uterine lining, a process which is complete about 10 days PF.
  • By this time the inner cell mass, which was a group of undifferentiated cells has become a bilayer disk, composed of hypoblast and epiblast cells
  • This bilayer disk gives rise to all the tissues of the human fetus, through a complex series of changes (i.e. gastrulation
32
Q

Gastrulation

A
  • converts the bilayer of hypoblast and epiblast cells into a trilaminar embryo
  • containing the three layers of Germ Cells (Ectoderm, Mesoderm and Endoderm)
  • occurring during days 14-18 PF
  • proliferation of epiblast cells, which then differentiate to form mesoderm cells;
  • these move into the space between the epiblast and hypoblast.
  • These mesoderm cells are thought to differentiate further to generate the endoderm, which replaces the hypoblast cells which are lost by apoptosis.
33
Q

When does gastrulation occur?

A

during days 14-18 PF

34
Q

What are the 3 layers of germ cells? What do they differentiate into?

A
  • Ectoderm (skin and CNS)
  • Mesoderm (muscles, blood, skeleton, heart, kidney)
  • Endoderm (gut, liver, lungs)
  • Muscular and vascular tissue are generally of mesodermal origin, so tissues are normally a mixture of germ layer types (e.g. muscle in the skin and gut).
35
Q

Neurulation

A
  • Neurulation has been initiated before gastrulation is complete.
  • Neurulation is the differentiation of the Ectoderm (Epiblast) to generate the CNS (Brain and Spinal cord), under the control of the notocord in the mesoderm of the developing embryo.
  • The early stages: development of the neural plate; this develops two folds, which increase in size until the meet over the neural groove and fuse to form the neural tube
36
Q

What is more common, excess digits or too few digits?

A
  • excess digits are more common
  • oligodactylyl = too few
  • polycactylyl = too many

Year 2 - LCRS - RDA (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions