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30 Cards in this Set
- Front
- Back
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Define mitosis.
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The process of cell division in which one cell divides into 2 identical daughter cells.
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Define cell differentiation.
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The process by which a cell develops from a less specialised to a more specialised type.
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What is a haploid cell?
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A cell which has half the usual number of chromosomes (23 in humans) e.g. female unfertilised egg & male sperm cell.
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What is a diploid cell?
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A cell which has the full number of chromosomes (46 in humans)
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Define embryo.
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'that which grows' - a developing human baby from weeks 0-8 of development.
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Define foetus.
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'offspring' - a developing human baby from the 9th week of development to birth.
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What is the endometrium?
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the innermost layer of the uterus into which the embryo implants
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What is a germ cell?
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a precursor that gives rise to gametes.
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What is a gamete?
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haploid reproductive sex cell (haploid) which joins with a gamete of the opposite sex to form a fertilised human cell/zygote. ovum & sperm
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Define zygote.
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Fertilised human cell which divides & develops to form an embryo.
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Define 'troph'.
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grow/nourish
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Define 'blast'.
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immature
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What is the trophoblast?
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the early placenta (immature structure that will eventually nourish the embryo
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what is a cyst?
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fluid-filled sac
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Define blastocyst.
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'immature cyst' - embryo at day 5-6 of development.
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Define epiblast & hypoblast.
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epiblast - immature structure above
hypoblast - immature structure below Embryoblast divides into epi & hypo blast layers in 2nd week of development |
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What are germ layers & name them.
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3 basic layers formed from the epiblast from which all tissues of the embryo develop. Ectoderm, mesoderm & endoderm.
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Define ectoderm & list what structures derive from it.
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Outer layer of cells.
Form: epidermis of skin, hair, mammary glands, mouth & anus, nerves & brain. |
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Define endoderm & list what structures derive from it.
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Inner layer of cells.
Form: GI tract & most related organs, & lungs. |
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Define mesoderm & list what structures derive from it.
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Middle layer of cells.
Form: many inner body structures including bones, muscle, dermis of skin, connective tissues, blood, heart, lymphatics, urogenital system, spleen, peritoneum. |
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What is the yolk sac?
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Early cavity, linked to the gut, which provides early nourishment to the embryo before the placenta takes over.
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Define umbilical.
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'relating to the centre'. Umbilicus is the site at which the developing baby is attached to the placenta via the umbilical cord.
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Define synctium/synctio-.
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Relating to cells which have coalesced together to form a multi-nucleated mass
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What is the synctiotrophoblast?
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Part of the placenta (trophoblast) which has formed a synctium, & which invades into the uterine wall.
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What is the cytotrophoblast?
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Part of placenta closest to the embryo which consists of cells.
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What is the amnionic cavity?
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Fluid-filled cavity which surrounds & protects developing embryo/foetus inside the uterus.
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What is a coelum & what are the 2 major coelomic cavities in the human body?
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Coelum = cavity lined by epithelium derived from mesoderm.
Peritoneal cavity - surrounds & cushions abdominal organs, lined by 2 layers of mesodermal membrane: visceral & parietal peritoneum. Pleural cavity - syrrounds lungs, lined by visceral & parietal pleura. |
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Explain the key events of gastrulation.
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The early embryonic disc develops into 3 layers.
Flattened embryonic disc becomes folded. |
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What is the process of implantation?
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Embryo begins to burrow into the uterine wall towards the end of week 1 of development.
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Blastocyst development DIAGRAM
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