Lecture 7 Flashcards
what are the steps of development of muscular system
- determination
- migration
- proliferation
- differentiation
- fusion
- maturation
what occurs in determination
myogenic precursor cells originate from the mesoderm germ layer of the embryo and collect into dense clusters known as somites
what occurs in migrations
cells migrate to portions of the embryo destined to be muscles of the limbs or body wall
what occurs in proliferation
once these myogenic precursor cells proliferate resulting in a tremendous increase in numbers
what occurs in differentiation
at a key point the cells become post mitotic and begin to synthesize muscle specific proteins such as actin, myosin, and desmin. these cells are now referred to as myoblasts
what occurs in fusion
under influence of additional chemical and genetic signals, myoblasts fuse with adjacent myoblasts and form myotubes or immature muscle fiber. this fusion is what provides muscle fibers with their characteristic of being multinucleated
what occurs in maturation
further muscle specific protein synthesis enables formation of the characteristic sarcomere units that represent the organism repeating unit comprising the skeletal muscle fiber
what factors are in determination and migration
MRFs
what factors are in proliferation
GFs
what factors are in differentiation
MRFs and GFs
what factors are in maturation
MRFs and innervation
what are myogenic regulatory factors
small proteins or peptides serve as molecule switches activating transcription of a series of muscle specific genes thus specifying cells to become myogenic cells
how can fibroblast cells be forced to convert to muscle cells
addicting of cancer causing agents
how are factors upregulated
activity or exercise
what are somites
focused collection of the mesoderm
