Muscular system review

Comparative Physiology of Skeletal, Smooth & Cardiac Muscle Fibers

Skeletal MusclesSmooth MusclesCardiac Muscles
  • Voluntary
  • Attached to bones or skin
  • Very long, cylindrical, multi-nucleated cells
  • Striated: packed with orderly arrangement of myofibrils
  • Not self stimulating: each fiber is innervated by a branch of a somatic motor neuron as part of a motor unit
  • Under control of the nervous system
  • High energy requirement: Lots of mitochondria, phosphocreatine, myoglobin
  • Fast contracting
  • No rhythmic contractions
  • Strength increases with stretching
  • Fatigues easily
  • Involuntary
  • Lines walls of most internal organs
  • Single, tapering, mono-nucleated cells
  • Not striated: Fewer myofibrils of varying lengths
  • Self stimulating: not individually innervated, impulse spreads from cell to cell
  • Under the control of the nervous and endocrine systems and various chemicals and stretching
  • Lower energy requirement: fewer mitochondria, phosphocreatine, myoglobin
  • Slower in contracting and rhythmic in some organs producing peristaltic waves along the organ
  • Rhythmic contractions
  • Under stress has a relaxation response
  • Does not fatigue
  • Involuntary
  • Found only in the heart
  • Branching chains of cells connected by porous intercalated discs, with single nucleus and striations
  • Striated: many myofibrils in orderly arrangement
  • Self-stimulating: impulse spreads from cell to cell
  • Under control of nervous and endocrine systems and various chemicals
  • Intermediate energy requirement
  • Intermediate speed of contraction yet contraction spreads quickly through tissue due to intercalated discs
  • Rhythmic contractions
  • Strength increases with stretching
  • Doesn't fatigue
Information collected from:

Colville, T. & Bassert, J. M. (2016) Clinical Anatomy and Physiology for Veterinary Technicians, Third Edition. St. Louis, MO: Elsevier.

Roffey, H. (2019). Muscular System I & II [Powerpoint slides]. Retrieved from htts://

Roffey, H. (2019). Muscular System III [Powerpoint slides]. Retrieved from

Posted by chance
Muscle Contraction Process
A video providing detailed animation on how skeletal muscle contracts and the sliding filament mechanism.

Source: Video by McGraw-Hill Animations, an educational company that has made multiple videos about biological processes.
Original link
Posted by chance
Crash Course - Muscles Part 1
A crash course Anatomy & Physiology video where Hank discusses the following:
  • How smooth, cardiac, and skeletal muscles create movement
  • The sliding filament model
  • Skeletal Muscles are made of protein fibers
  • Actin and myosin filaments
  • How calcium and ATP causes binding and unbinding
Original link
Posted by chance
Sliding Filament Theory, Sarcomere, Muscle Contraction, Myosin
An article discussing how muscles contract and what molecules are necessary for a tissue to change its shape.

Source: Article published in Nature Education, by Krans.
Original link
Posted by chance