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20 Cards in this Set
- Front
- Back
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How many somites do we have?
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42-44
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How many of each type of somite do we have?
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4 occipital
8 cervical 12 thoracic 5 lumbar 5 sacral 8-10 coccygeal |
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what are the 3 parts of a somite?
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Dermatome (dermis of skin)
Myotome (skeletal muscle) Sclerotome (bone) |
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the myotomes in the thorax and abdomen are split into 2 regions called:
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-the epaxial division (back and neck muscles)
-the hypaxial division (trunk and limb muscles) |
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the epaxial division of the trunk and abdominal somites is innervated by...
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the dorsal rami
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the hypaxial division of the trunk and abdominal somites is innervated by...
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the ventral rami
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Does vertebral column undergo intramembranous or endochondral ossification?
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endochondral
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at what week does muscle differentiation begin? i.e. what week do myoblasts form?
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week 4-5 (myoblasts form)
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at what week do limbs begin to develop?
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week 4
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what is the apical ectodermal ridge?
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a region of thickenined epithelium at the tip of a limb bud
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which determines the form and feather distribution: mesoderm or ectoderm?
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mesoderm
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which determines the feather type: mesoderm or ectoderm?
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ectoderm
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define amelia
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failure to develop a limb
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define meromelia
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development of a partial limb
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limb bud development is controlled by the homeobox genes. T/F?
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T
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What is the role of retinoic acid and morphogenetic proteins? If they fail to perform their role, what happens?
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They determine the pattern of limb development and programmed cell death.
If they fail to perform their role, either polydactyly (too many digits) or syndactyly (fused digits) occurs. |
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at what week do nerves grow out to innervate developping muscles?
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week 5 (right when the myoblasts are forming)!
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fill in the blanks.
When the nerve cord develops, it as _____ (more/less) neurons than it needs. If a given neuron finds a target it will _____ (die/survive). Else it will (die/survive) |
more. survive. die.
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How many arteries to each somite?
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1 (segmental artery)
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of the 3 limb axes, what is the order in which they develop?
ant/post axis proximal/distal axis ventral/dorsal axis |
1. ant post
2. dorso-vental is determined 2nd 3. proximal-distal is determined last |
