Guyton chapter 8 | Types of Smooth muscles, multi-unit smooth muscles, unitary smooth muscles | Lc43
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Smooth muscles are distinct from
Smooth muscles are distinct from skeletal muscles because their appearance is not striated rather, they appear smooth.
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The dark and light bands present on skeletal muscles are not present on smooth muscles.similarly the smooth muscle fibers are very small in diameter and length as compared to the skeletal muscle fibers.
Smooth muscles of different viscera are differentiated from each other depending upon their physiology appearance, their response to different types of stimuli, the type of innervation and their functions.
Broadly the smooth muscles are classified into two types.
1.Multi unit smooth muscles.
2.Unitary smooth muscles also known as syncitial smooth muscles or visceral smooth muscles.
Multi unit smooth muscles consist of seperate, independent, discrete muscle fibres that are inervated by separate nerve fibres. All the fibers of multi unit smooth muscles contract independently. As they are inervated separately. Best example of multi unit smooth muscles are muscles of iris and pupil in eye and muscles responsible for erection of hair in skin. Each muscle fiber of the United has special coting of connective tissue, that prevents spread of action potential or excitation from one fibre to the other.As they are inervated separately so they are more responsive to nervous stimuli as compared to other non nervous stimuli.
Unitary smooth muscles are composed of sheets of smooth muscle fibers, the membrane of each fiber is attached with the membrane of other fibers, as well as there are gap junctions between all fibers, so, impulse or action potential from one fiber can easily get transferred to the other. Hence they behave like a single unit and the whole unit contract at one and the same time. Unitary smooth muscles are present in viscera in abandandce so they are also Known as VISCERAL smooth muscles, and as the action potential in these fibers spread between each other and they contract like a single unit, that behave like SYNCYTIUM, that's why they are also Known as syncitial muscles.
Dr chamkani.
#physiology
#myology
https://amzn.to/3hQHHdR
The dark and light bands present on skeletal muscles are not present on smooth muscles.similarly the smooth muscle fibers are very small in diameter and length as compared to the skeletal muscle fibers.
Smooth muscles of different viscera are differentiated from each other depending upon their physiology appearance, their response to different types of stimuli, the type of innervation and their functions.
Broadly the smooth muscles are classified into two types.
1.Multi unit smooth muscles.
2.Unitary smooth muscles also known as syncitial smooth muscles or visceral smooth muscles.
Multi unit smooth muscles consist of seperate, independent, discrete muscle fibres that are inervated by separate nerve fibres. All the fibers of multi unit smooth muscles contract independently. As they are inervated separately. Best example of multi unit smooth muscles are muscles of iris and pupil in eye and muscles responsible for erection of hair in skin. Each muscle fiber of the United has special coting of connective tissue, that prevents spread of action potential or excitation from one fibre to the other.As they are inervated separately so they are more responsive to nervous stimuli as compared to other non nervous stimuli.
Unitary smooth muscles are composed of sheets of smooth muscle fibers, the membrane of each fiber is attached with the membrane of other fibers, as well as there are gap junctions between all fibers, so, impulse or action potential from one fiber can easily get transferred to the other. Hence they behave like a single unit and the whole unit contract at one and the same time. Unitary smooth muscles are present in viscera in abandandce so they are also Known as VISCERAL smooth muscles, and as the action potential in these fibers spread between each other and they contract like a single unit, that behave like SYNCYTIUM, that's why they are also Known as syncitial muscles.
Dr chamkani.
#physiology
#myology
4 سال پیش
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