Differences between smooth and skeletal muscle fibers

What is the shape of a single smooth muscle

Spindle shaped

Where is the nuclei of a smooth muscle f

The center

Does smooth muscle have the coarse CT sheaths that skeletal muscle has

No

Is there perimysium, endomysium, and/or epimysium in smooth muscle

There is small amount of endomysium found between smooth muscle fibers and contains blood vessels and nerves

Does smooth msucle have neuromuscular junctions

No, it has varicosities

What are varicosities

The numerous bulbous swellings in smooth muscle's Innervates nerve fibers of the autonomic nervous system

What do varicosities form in smooth muscle

They form diffuse junctions that have wide synaptic clefts

Do smooth muscles have an sER or t Tubulues like skeletal muscles do

No. They have a less elaborate sER with no terminal cisternae. There are no t tubulues

Does smooth muscle require calcium

Yes

How does calcium get to the smooth muscle fibers

The caveolae

What are the caveolae

Punchline infoldings of the smooth muscle that contain large amounts of Ca2+ channels. This is like the skeletal muscles t-tubules

How are smooth muscles fibers connected to each other

By gap junctions

Are there striations in smooth muscle

No

Are there sarcomeres in smooth muscle

No

Are there actin and myosin in smooth muscle

Yes. The myosin is much shorter

How do the myosin in smooth muscle differ from skeletal muscle (heads)

The myosin are much shorter, but have heads along the entire length

Is there troponin in smooth muscle

No, there is calmodulin

What is calmodulin

The calcium binding site in smooth muscle

Is there tropomyosin in smooth muscle

Yes

What helps to resist tension in smooth muscle

The intermediate filaments arranged in a lattice-like structure

What are dense bodies

They are tethered to the sarcolema and act as anchoring points for actin. They are the a-discs of smooth muscle.

How do smooth muscles look when contracted

Like a corkscrew

What causes the corkscrew contraction of smooth muscle

The contractile protein bundles crisscross within smooth muscle and spiral down the long axis of the cell like the stripes of a candy cane