Smooth muscle Flashcards
Smooth muscle characteristics
Widely distributed in the body Smaller cells than skeletal muscle fibers Single nucleus Spindle-shaped No striations
Dense bodies & Dense areas
where actin myofilaments are attached in smooth muscles.
Equivalent of Z disks
Intermediate filaments
Non contractile filaments that attch to the dense bodies
Contraction speed
Slower than skeletal muscle,
- Ca2+ diffuses at a slower rate
How are smooth muscle contractions stimulated?
Neurally adn hormonally
Calmodulin
A protein that Ca2+ binds with
Myosin kinase
enzyme activated by Ca bound with calmodulin; transfers a phosphate group from ATP to heads of mysoin molecules to form cross-bridges
Myosin phosphatase
The enzyme that causes the relaxation of smooth muscle
Types of smooth muscle (2)
Visceral
Multiunit
Visceral smooth muscle
More common
Digestive, reproductive, and urinary tracts
Multiunit smooth muscle
walls of blood vessels, arrector pili, capsule of spleen
only contracts when stimulated by hormones
Duchenne’s muscular dystrophy
Muscles in children atrophy and they are very week
Cardiact muscle characteristics
Striated
One nucleus
Intercalated disks
specialized cell-to-cell attachments
Sarcopenia
Muscle atrophy - age related reduction i muscle mass
Other skeletal muscle characteristics that occur in aging
reduced msucle mass
increase time to contract in response to simuli
reduced stamina
increased reovery time
FIbromyalgia
chronic, widespread pain in skeletal muscle with no known cure
Muscular dystrophy
genetic diorders that cause muscles to degenerate and atrophy
TEndinitis
imflammation of tendon due to overuse
Fibrosis
scarring of damaged cardiac or skeletal muscle due to deposition of connective tissue
Fibrositis
inflammation of fibrous connective tissue, resulting in soreness.
