smooth muscle Flashcards
is smooth muscle voluntary or involuntary control?
involuntary
smooth muscle contractions produce __________
constriction
smooth muscle is organized in _______________
multidirectional contractile units
how many nuclei do smooth muscle have?
one
how is smooth muscle classified?
1 - by location
2 - by contraction pattern
3 - by their communication with neighboring cells
what are the 2 contraction patterns of smooth muscles?
1 - phasic (ex. peristalsis)
2 - tonic (ex. sphincters)
what are the 2 classifications of communication between neighboring cells
1 - single-unit/unitary/visceral smooth muscle
2 - multiunit smooth muscel
__________ smooth muscle cells are connected by gap junctions, and the cells contract as a single unit
single-unit
_______ smooth muscle cells are not linked, and each cell must be stimulated independently
multi-unit
what is an example of a phasic smooth muscle that is usually relaxed?
esophagus
what is an example of a phasic smooth muscle that cycles between contraction and relaxation?
intestine
what is an example of a tonic smooth muscle that is usually contracted?
sphincter
what is an example of a tonic smooth muscle whose contraction is varied as necessary
vascular smooth muscle
smooth muscles are the _______ to contract and relax
slowest
(skeletal is the fastest and cardiac is in the middle)
T or F: smooth muscle has no sarcomeres
T
T or F: actin is more plentiful in smooth muscle
T
T or F: smooth muscle lacks troponin
T, but actin is still associated with tropomyosin in smooth muscle
T or F: myosin filaments are longer in smooth muscle and the entire surface of the filament is covered with myosin heads
T
T or F: smooth muscle has an extensive cytoskeleton consisting of intermediate filaments and dense bodies
T
T or F: in smooth muscle the amount of SR varies and is less organized
T