Lecture 27: Cardiac & Smooth Muscle Flashcards
Are all single unit smooth muscle cells innervated?
No. Only inner layer, action potential spreads through gap junctions to the rest.
Are all multi-unit smooth muscle cells innervated?
Yes, allows for finer control in muscles like the eye.
What are examples of multi-unit and single-unit
Single unit: Digestive, urinary and reproductive tracts.
Multi Unit: Pili muscles skin, eye muscles, blood vessels
Explain the excitation/contraction process in smooth muscle.
Action potential or hormones trigger Ca2+ rise, Ca2+ binds to calmodulin.
Ca-calmodulin complex activates MLCK.
MLCK activates MLC which activates crossbridge.
What do MLC and MLCK stand for?
MLC: myosin light chain
MLCK: myosin light chain kinase.
Which type of junctions connect smooth muscle cells?
Gap junctions.
What’s the difference in shape and nuclei of muscle cells?
Skeletal: Long, cylindrical, multinucleate.
Cardiac: Mononucleate branching cells.
Smooth: Mononucleate spindle-shaped cells.
Which types of muscle are striated? (have striated sarcomeres)
Skeletal and cardiac, NOT smooth.
What is the function of striations?
To organise sarcomeres and provide a stronger force along one axis.
In which types of cell do action potentials spread from cell to cell?
Cardiac and single-unit Smooth muscle. NOT skeletal.
Which types of muscle offer voluntary movement?
Skeletal, NOT cardiac or smooth.
Rank the types of muscle in order of contraction speed. (high to low)
Skeletal, cardiac, smooth.
