RDA; Lecture 1, 2 and 3 - Complexity of Labour, Embryology and Child development Flashcards Preview

Y2 LCRS 1 - Pharm, Endo, Reproduction > RDA; Lecture 1, 2 and 3 - Complexity of Labour, Embryology and Child development > Flashcards

Flashcards in RDA; Lecture 1, 2 and 3 - Complexity of Labour, Embryology and Child development Deck (245)
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What is the difference between the gestational age and post-fertilisation?

  • Gestational age starts from the first day of the last period;
  • post-fertilisation is 2 weeks less than gestational age -> makes a difference at the beginning of the pregnancy, but not really at the end of the pregnancy.
Difference between IVF gestational age and non-IVF GA (around 2/2.5wks) -> important as it can change whether the baby will be resuscitated or not (24 vs 22 wks)


What are the main size gains that occur in each trimester?

Last 2 trimesters are for growth of foetus, but first trimester is for development


What are the carnegie stages of human development?



What occurs in the first trimester?



How are the carnegie stages broken up into weeks of pregnancy?



What is the difference between a blastocyst, embryo and foetus?

Red area is the liver as the RBC are produced in the liver in the embryo as there is no bone marrow, yolk is used for nutrition -> very translucent. Embryo is baby up to week 8, foetus is baby for rest of pregnancy


What is a conceptus?

Everything produced from a fertilized egg


What is an embryo?

Cells that give rise to everything at the beginning not just the baby -> terms are used in 2 different ways; baby up to week 8 of development OR for the first week then whole conceptus is embryo, after blastocyst differentiation, then only baby tissue is foetus


Why does cell proliferation occur?

Changes in response to ‘growth factors’

Changes in receptor expression

May be due to changes in cell survival

All paracrine or autocrine regulation


Why do cells move?

Chemo-attractants (local production, paracrine effects), cognate receptors (expressed on target cells) -> needs facilitation, requiring change in tissue structures; remodelling of tissues (ECM) and proteases and inhibitors need to be produced and activated


What are the steps of differentiation that occur in foetus?

Paracrine regulation

Receptor expression

Necessary in target cells

Loss of proliferation

Not necessarily in embryo or fetus

Cells can differentiate and proliferate at the same time


How does cell loss occur in foetus?

Apoptosis -> regulated cell death, controlled by paracrine factors mainly


How can concentration of paracrine stimulus affect regulation of cells?

Some cells exposed to different regulators and different concentrations, which by working together can bring out how cells behave -> occurs in 3D (shown here in different planes) and looks like a limb bud (occurs in embryo proliferation)


How can different regulators work together in the embryo?



How do genetic factors regulate development?

Controlled by signals from genes.

Complex gene interactions occur throughout development to form a normal fetus.

Hox genes, with retinoic acid controlling activation of Hox genes


What does embryonic development need?

Gradients of factors

Combinations of factors

Temporal changes in factors or responses to them


What is the bilaminar disc (~9d PF)?

Epiblast (yellow) and hypoblasts (blue) -> circular disc cut in the middle


What is gastrulation?

Becomes more elongated -> Gastrulation is a phase early in the embryonic development of most animals, during which the single-layered blastula is reorganized into a trilaminar ("three-layered") structure known as the gastrula. These three germ layers are known as the ectoderm, mesoderm, and endoderm.


How is the germ layer formed?

Proliferating and differentiating to form mesoderm cells, which move towards the hypoblast -> forming the germ layers; hypoblast is bumping into mesoderm cells which then undergo another differentiation stage, forming the endoderm, with hypoblast being lost via apoptosis


What does gastrulation result in?

Epiblast becomes ectoderm, mesoderm is in the middle, endoderm is where the hypoblast was


What do the 3 germ layers become?

NB: very few tissues are of one specific type -> skin is both ectoderm and mesoderm


What is neurulation?

Occurs at the same time as gastrulation -> can see the primitive streak;

Neurulation refers to the folding process in vertebrate embryos, which includes the transformation of the neural plate into the neural tube.

The embryo at this stage is termed the neurula.

Notochord (acts as negative regulator, not allowing certain things to happen) formed from mesoderm, and upper epiblast layer is turning into neural plate which forms the CNS.

Proliferation cells, grow and meet in the middle forming the neural tube which will then become the CNS. Skin overlies the CNS, which explains why some neuroblastomas can affect the skin as well as the NS, as they have the same embryological origin.

By day 21, 3D embryo is developing, with mesoderm becoming more dimensional


How does the body cavity close?

Umbilical cord is a gap in the body wall, where the yolk was


How does the embryo fold head to tail?



What occurs in the 2nd month of development?

Faces developing, hands developing, eyes developing from an early stage; apoptosis used to remove webbing in between fingers and remove our tail


When do each of the systems develop?



How does the CNS develop?

Brain development occurs in 2 separate halves -> with fusion of tissues and elaboration occurs -> neuropores then fuse to give a complete tube that is the CNS


What is spina bifida?

Twin/two spines, with 2 areas of tissue -> bulges of tissue and depending where they are and what is in them decides the problems that it is going to cause -> above the point is normal;

Incidence of 1-2 per 1000 pregnancies;

Surgery can help anatomical but not functional problems and folic acid (need to take it earlier to have enough reserve for baby) can prevent it, primary problem is failure to complete neurulation and problem is present within 4 weeks of fertilisation


How is spina bifida caused?

A gap is left where the fusion would have occurred -> posterior neural chord hasn't closed properly


What are the types of spina bifida?

Occulta has a patch of hair, with vertebra not being formed properly; in meningocele is a bulge of CSF; myelomeningocele includes neural tissue and CSF -> development of bones of spine are controlled by neural tissue, which means it doesn't cut off the neural tissue in spina bifida

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