Pgs. 218-219
Muscular Dystrophy
 Weakening/breakdown of the voluntary muscle cells
 A group of over 30 types of inherited muscular
diseases
 Duchenne’s MD:
 Recessive; Sex-linked
 More common in boys
 Affects a protein that maintains the sarcolemma
Disorders of the
Neuromuscular Junction
 Myasthenia Gravis:
 Auto-immune disease
 Antibodies destroy or block the receptor sites on the
sarcolemma

Results in failed transmission of nerve impulses = atrophy
 Eaton-Lambert Syndrome:
 Problem w/Calcium channel in axon terminals


Results in decreased release of Ach
Potentially caused by cancer
 Black Widow venom:
 Causes a complete depletion of Ach
 Leads to temporary paralysis
Growing and Aging
 Gross motor skills dominate early in life followed by
fine motor skills
 Peak performance is around adolesence
 Training improves certain skills
 Older individuals begin to lose muscle mass
 Decrease of about 50% by age of 80
 Can counteract this with exercise; weight lifting
 Failure to use muscles can result in loss of muscle mass
or atrophy