Exam 4 Flashcards
SKELETAL MUSCLES & PHYSICAL PERFORMANCE
Myology
scientific study of muscles & their parts
Generally speaking, 2 main units exist in the muscular system… what are they?
structural unit: muscle fiber or muscle cell
functional unit: motor unit
Skeletal muscle fibers are comprised of 2 primary constituents
- sarcoplasm: muscle cytoplasm
- myofibrils: sarcomeres in series-contractile elements
Gross muscles may be comprised of how many muscle fibers?
only a few or as many as 1 million
Structural unit
muscle fiber/muscle cell
Functional unit
motor unit
All muscle fibers are supplied with nerves (innervated) by terminal branches of a single ___ ___ ___?
alpha efferent axon
How many motor units are located in each gross muscle?
multiple
What does it mean if a motor unit is recruited?
all fibers w/in it are concurrently contracting
As force demands increase…
more motor units are recruited
Muscles containing a small # of muscle fibers per motor unit are capable of smaller/larger gradations (degrees, stages) in force output?
smaller
Sarcoplasm
~25% protein in a non-contractile configuration
~75% fluid
Myofibrils
various protein filaments configured to enable the contractile process
-series of sarcomeres
Main filaments involved in contractions
myosin & actin
Smaller filaments loosely bound to actin when the myofibril is relaxed
troponin & tropomyosin
Muscle fibers have how many nuclei?
multiple
multi-nucleated