Cardiac & Smooth Muscles
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Like skeletal muscles, cardiac muscles are also __. Cells are __ than skeletal muscle and have __ nucleus
striated; smaller; one
Cardiac muscles also branch and interdigitate - can withstand high pressures.
__ and __ cells initiate & coordinate heart contractions.
The heartbeat is __ - generated by the heart muscle itself.
The ANS modifies the __ of pacemaker cells, but is not necessary for their function.
Smooth muscle is in most internal organs and is under __ control.
Neural influences on smooth muscle come from ANS
__ cells are arranged in sheets - have electrical contact via gap junctions.
Action potential in one cell can spread to all others in the sheet.
__ in digestive tracts cause __, causing contraction. __ causes the same cells to __, leading to fewer contractions.
- ACh; depolarization & action potentials;
- NE; hyperpolarize
ANS neurotransmitters can alter membrane resting potentials & affect the rate at which smooth muscle fire action potentials, thus controlling smooth muscle contraction.
(page 57 on slide)
Smooth muscle contraction:__ influx to sarcoplasm is stimulated by stretching, action potentials or hormones.
Smooth muscle contraction: Ca2+ binds with __, which activates __, which phosphorylates __, which then can bind & release __
- myosin kinase;
- myosin heads;
smooth muscle contraction story
- Ca2+ entering sarcoplasm binds & activates calmodulin.
- Activated calmodulin activates myosin kinase, which phosphorylates myosin heads (ATP to ADP)
- Phosphate group attaches to myosin head.
- Myosin head binds to actin.
(page 59 on slide)
__ causes the myosin head to unbind from actin.
Phosphate group is no longer attached to myosin.
(page 59 on slide)
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