Question

Difference between skeletal and smooth muscle contraction

Answer 1

1.Skeletal muscles are attached to the bones.
Smooth muscles line up the visceral organs viz. Intestines,blood vessels,pupils etc (therefore also known as visceral muscles.)

2.Skeletal muscles perform voluntary actions.
Smooth muscles are responsible for involuntary reflexes and actions.

3.Skeletal muscles are well striated.
Smooth muscles lack striation.
(Hence,the name-Smooth muscle)


4.Skeletal muscles are innervated by Peripheral Nervous System i.e. PNS

Smooth muscles are innervated by Autonomic Nervous System i.e. sympathetic and parasympathetic nervous systems.


5.Skeletal muscles help perform movements i.e walking,running,jumping,writing etc

Smooth muscles are responsible for vital body functions i.e. breathing,digestion,urine formation etc.

Note that cardiac activity does not depend upon smooth or striated muscles.Cardiac muscle is a special category assigned for this vital function.


6.Calcium is the most vital substance in the process of skeletal muscle contraction.
Neurotransmitters like Acetylcholine(parasympathetic innervation) or Norepinephrine(sympathetic innervation) play important role in smooth muscle contraction.

7.Types of skeltal muscles-
Red (also known as type1,slow,aerobic,tonic,oxidative)
White(also known as type 2,fast,anaerobic,phasic,glycolytic)

Types of smooth muscles-
Single unit(most of the smooth muscles are of this type)
Multi-unit eg-Ciliary muscles

8.Both types of muscles contain actin and myosin filaments,but in Skeletal muscles,Actin:Mysoin=2:1,while for smooth muscles,Actin:Mysoin=10:1.
Actin and Myosin are muscle filaments which contract or relax,causing the whole muscle to perform the desired action.

9.Troponin is present in skeletal muscles,while Calmodulin is present in smooth muscles.
Troponin and Calmodulin are a Ca-binding proteins which are responsible for muscle contraction.