Muscle Histology II Flashcards
Each myofiber is connected to a motor _______.
Neuron
What is the chemical neurotransmitter for skeletal muscle? (Full name and abbreviation)
Acetylcholine, ACh
A myofiber only contracts when stimulated by its nerve
Motor______ _____.
End Plate
At the end plate, the sarcolemma is extensively ______ to increase _______ ________.
Folded
Surface Area
What purpose does the motor end plate serve?
Provides a large surface area for millions of ACh receptors
What is a graded response with skeletal muscle?
Our muscle contractions are relatively smooth and can vary in strength as different demands are put on them. Variations in the degree of a muscle contraction are referred to as graded responses.
What does innervation ratio mean in the context of skeletal muscle?
The ratio of motor neurons to muscle fibers
What is an example of an innervation ratio for fine control?
Muscles for the eyes; 1:8 ratio
What is an example of an innervation ratio for strength an power?
Quad; 1:2,000 ratio
What is muscle recruitment?
To increase contractile power, more units are stimulated
Muscle units of a single motor unit are not clustered all together, but are dispersed throughout the _______ ______.
Whole muscle
When muscles are stimulated, this causes a _____ contraction over a wide area, not a localized twitch in a small region.
Weak
What is an advantage of multiple motor units within a muscle?
They are “able to work in shifts.” Muscle fibers fatigue when subjected to continued stimulation, and so other motor units take over while fatigued ones rest.
In muscle contraction, or the “sliding mechanism” what structures shorten?
Myofiber
Myofibrils
What defined area shortens during the “sliding” mechanism?
The sarcomere, or area from Z line to Z line
