Download - Muscular Contractions
MUSCULAR CONTRACTIONS
Contracting and Relaxing Skeletal Muscle
Anatomy of a Muscle Fiber (Cell)
Sarcolemma Myofibril Sarcomere Z line
Anatomy of a Sarcomere
Actin Myosin
Contraction Overview
Lovely artwork courtesy of David Goodsell and the RCSB Protein Data Bank
Steps of a Muscle Contraction
Nerve causes release of acetylcholine (ACh)
Steps of a Muscle Contraction
Reception of ACh causes an action potential (electrical nerve signal) in muscle cell
Steps of a Muscle Contraction
Action potential causes release of calcium in muscle cell
Meanwhile…
Steps of a Muscle Contraction
Calcium binds, forming troponin complex and revealing myosin binding sites.
Steps of a Muscle Contraction
Sliding filament theory
Contraction Overview
Lovely artwork courtesy of David Goodsell and the RCSB Protein Data Bank
Relaxation
Acetylcholinesterase breaks down Ach Active transport prepares the muscle cell for
future action potentials Active transport removes free calcium from
muscle cells ATP breaks actin-myosin linkage
Relaxation
Interference
Botox & botulism – block acetylcholine release
Rigor mortis – can’t keep calcium out of cells so muscles contract, lack of ATP prevents myosin from releasing actin