Muscle phsyiology - smooth muscle Flashcards
Is smooth muscle striated or unstriated
Un striated hence the name
What does smooth muscle NOT have which the other two muscle types have ?
They have no sarcomeres, which is why there are no striations.
What are the cavelolae?
Caveolae stores the calcium in smooth muscle.
It doesn’t have a sarcoplasmic reticulum.
What are dense bodies ?
Dense bodies, one of the most prominent structures in smooth muscle cells, have been regarded as the anchoring sites for actin filaments, similar to the Z-disks in striated muscle
What do actin molecules attach to in smooth muscle ?
dense bodies
Smooth muscle has no troponin, what does it have instead ?
It is replaced by calmodulin.
Therefore calcium binds to the calmodulin.
Where is the smooth muscle in the body ?
- GI tract
- Urino-genital system
- Respiratory system - bronchioles
What are the two types of smooth muscles
- Single unit
- Multiple unit
What are single unit smooth muscles
- Arranged in the forms of large sheets
- Responds as a single unit
- Cells linked by gap junctions
- They are spontaneously active
What are multiple unit smooth muscle
What is the sliding-filament theory ?
Explain the production of force in smooth muscle
Smooth muscles have unique features in production of force:
- versatile
- very fatigue resistant
- low energy consumption
- allows muscle tone
- contract over much greater lengths (durations)
e.g. skeletal muscle 1/3 vs. smooth muscle 2/3
What is the innervation of smooth muscle ?
Nerve branches with small swellings known as Varicosities
