Completion of Skeletal Muscle and comparison to Smooth Muscle

Outline

Classification of Skeletal muscle Slow twitch versus fast twitch Oxidative versus glycolytic

Skeletal Muscle Genetic Diseases

Smooth Muscle Types of smooth muscle cells Smooth muscle contraction Smooth muscle relaxation

Smooth muscle compared to Skeletal Muscle

Classification of skeletal muscle

Speed of contraction

Resistance to Fatigue

Which type of muscle fibers are used for these two activities?

Fast Twitch Slow Twitch

Weight liftingPianist

Muscular Disease

Muscular Dystrophy Sex linked recessive Dystrophin is mutated

Myasthenia Gravis Decreased number of acetylcholine receptors

TYPES OF SMOOTH MUSCLE CELLS

SMOOTH MUSCLE CONTRACTION

NO SARCOMERES!Presence of Dense Bodies EXTRA CALCIUM STORAGE SITES

SMOOTH MUSCLE CONTRACTION at the MOLECULAR LEVEL

No sacromeres No troponin

Look inside the smooth muscle cell

Smooth Muscle Relaxation

Comparisons: Smooth versus Skeletal

Increase cytosolic calcium

Calcium binds calmodulin

Ca++Calmodulin activates MLCK

MLCK activates myosin ATPase

Shortening

Increase of cytosolic calcium

Calcium binds troponin

Alteration in troponin moves tropomyosin

Myosin binds actin

Shortening