108 Flashcards
108
what is accretion
increase in size by gradual addition of smaller parts
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what is apoptosis
programmed cell death
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what is differentiation
the process by which cells aquire a cell type
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what is ectoderm
the outermost of the three germ layers giving rise to skin and other tissue
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what is an embryo
the organism between the first division of the zygote until it becomes a foetus at 8 weeks
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what is gastrulation
the stage of development when the embryo is restructured by cell migration ( giving rise to the 3 germ layers)
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what is induction
the action of inducing cells to change, usually in response to signalling molecules
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what is mesoderm
the middle of the three germ layers that gives rise to connective tissue, muscles and the circulatory system.
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what is a morphogen
a substance that governs morphogenesis by eminating from a localized source to form a concentration gradient during embryonic development.
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what is the neural crest
cells from the ectoderm migrate and generate many differentiated cell types
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what is the neural plate
a thick flat bundle of ectoderm which develops in the empbyo into the neural tubeand subsequently the nervous system.
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whats an alantois
extension of the primitive gut or yolk sacinto the umbilical cord
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what are amnioblasts
calls of the amniotic membrane from the epiblast
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what is an amnion
a thin tought membraneous sac that encloses the embryo or fetus. Filled with serous fluidin which the embryo is suspended
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what is a blastocyst
the early embryoas a sphere of cells with a fluid filled central cavity
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what are blastomeres
any cell resulting from cleavage of a fertilised egg early in embryo development
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what is chorionic
the outermembrane enclosing the embryo
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what is a coelom
fluid filed body cavity lined by cells derived from mesoderm
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what is a cytotrophoblast
the innder layer of the trophoblast
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what is the ectoderm
the outermost germ layer from which the epidermis, nervous tissue and sense organs develop
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what is an embryoblast
any of the germinal disk cells of the inner mass in the blastocystthat form the embryo
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what is the notocord
a rod of cells constituting the foundation of the axial skeleton
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what is an oocyte
a cell from which an eggor ovum develops by meiosis.
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what is the syncytiotrophoblast
the syncytical outer layer of trophoblast
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what is the trophoblast
the outermost layer of cells on the blastocyst that attaches the fertilised ovum to the uterine walland serves a nutritive pathway for he embryo.
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autosomal recessive condition
cystic fibrosis, sickle cell, tay sachs, spinal muscular atrophy
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x linked recessive diseases
duchenne muscular dystrophy, haemophilia A, red-green colour blindness
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autosomal dominant diseases
huntingtons, marfan, familial hypercholesterolaemia, spinocerebellar ataxia, long QT syndrome
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% risk of offspring getting an autosomal dominant disease
50%
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% risk of offspring getting an autosomal recessive disease
25%
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carriers and affected in x linked recessive disorders
50% of sons affected, 50% daughters are carriers
