Skeletal Muscle Flashcards
Organization of skeletal muscle
Whole muscle (organ)
Fascicles (bundles of muscle cells)
Muscle fibers (individual cells)
Myofibrils (intracellular structure)
Myofilaments (myosin and actin)
Sarcolemma
Cell membrane
Sarcoplasm
Cytoplasm
Sarcosomes
Mitochondria
Sarcoplasmic reticulum
Smooth endoplasmic reticulum
Radially oriented, tubular invaginations of the cell membrane
Transverse tubules -aka T tubules
Z line to Z line makes
Sarcomere
Titan and nebulin are
Giant accessory proteins
Difference between Titin and nebulin
Titan spans one Z disk to M line. Nebulin attaches to Z but does not extend M
I band is made of
Thin filament only
Made of regions where both thick and thin filaments overlap
A band
Clear band in the middle of A band
H zone
Represents the proteins to which thick filaments attach
M line
Accessory proteins that link the thin filaments together
Z disc
Provides elasticity and stabilizes myosin
Titin
Thick filaments are
Myosin
Thin filaments are
Actin
Force created by contracting muscle
Muscle tension
Weight that opposed contraction.
Load
Creation of tension in muscle (requires ATP)
Contraction
Release of tension
Relaxation.
Sliding filament theory
The actin and myosin connecting and contracting
Can the muscular function or muscles play a part in timing of death? T/F
True
A reversible condition in which an exercising muscle is no longer able to generate or sustain the expected power output
Fatigue
Fatigue is influenced by
- intensity and duration
- using aerobic or anaerobic metabolism
- muscle composition ( fast vs slow) twitch
- individual fitness level
Fatigue causes classified into
Central and peripheral
Slow twitch
Smaller diameter, darker color due to myoglobin, and fatigue-resistant
Fast twitch
Larger diameter, pale color, easily fatigue, glycolytic
Central fatigue mechanisms
Psychological effects
Protective reflexes
What type of fatigue is feeling tired
Central fatigue
Where does action potential begin
Neuromuscular junction
Z line to Z line =
sarcomere
when a muscle fiber is relaxed the cross bridge binding site on the actin is covered by what
tropomyosin
A bands are dark or light
dark
I bands are dark or light
light
how can you increase the force generated by a single muscle fiber
by increasing the frequency at which action potential stimulates the muscle fiber
does a single twitch represent the maximum tension that a muscle fiber can have
no
stimuli closer together do not allow the muscle to relax is
summation
tetanus
action potential stimulation of the muscle fiber occurs at a high frequency so that relaxation diminishes and it reaches its maximal contraction
incomplete (unfused) tetanus
muscle fiber does not reach maximum value and the fiber relaxes slightly between stimuli
complete tetanus
maximum tension is achieved and it stays there, muscle does not relax
basic unit of contraction in a skeletal muscle
motor unit
one somatic motor neuron and the muscle fibers it innervates
motor unit
muscles used for fine motor actions may only contain ___ muscle fibers
3-5
muscles used for gross motor actions may contain ___ muscle fibers
hundreds to thousands
DHP and RYR are in relation to
excitation- contraction coupling
botulinum neurotoxin prevents the release of ___ into the junction
ACh
effective in the treatment of conditions characterized by muscle hyperactivity
botox
myasthenia graves reduces the efficiency of
neuromuscular transmission
a standard acetylocholinestrase inhibitor drug used to treat myasthenia graves
neostigmine
