Exam 3 : Ch. 9 & 10 Muscles & Muscular System Flashcards
Functions of the Muscular System
MMGPS:
- Maintain Posture
- Move Bones
- Generate heat
- Produce movement
- Stabilize joints
NOT functions:
- protect the brain
- act as levers
- absorb heat
Continue this pattern from larger units to smaller units
Muscle Fascicle Muscle Fiber Myofibril Filaments
epimysium
fibrous connective tissue that surrounds the entire muscle
perimysium
surrounds a fascicle (bundle of muscle fibers)
endomysium
surrounds each muscle fiber (around each cell)
Muscle contraction involves the shortening of:
Muscle Fiber
Muscle Type Characteristics:
cells in branching, interwoven network; intercalated discs; involuntary action
Cardiac
Muscle Type Characteristics:
cells are fibers, usually cylindrical & multinucleate; voluntary action
Skeletal
Muscle Type Characteristics:
cells spindle-shaped, uninucleate; no distinct sarcomeres, involuntary action
Smooth
Describe mature smooth muscle cells
- not striated
- involuntary,
- found in walls of hollow organs (visceral)
- uninucleate
Describe Skeletal muscle cells
- striated
- voluntary; usually attached to the skeleton (except sphinters),
- multinucleated.
What neurotransmitter plays a key role in generating an action potential in the sarcolemma?
Acetylcholine (ACh)
Between neurons and muscle is a synapse with the special name of
neuromuscular junction.
One “unit” of a myofibril is
Sarcomere
Polarized
The resting sarcolemma of the muscle cell can best be described as
Depolarized
An action potential or impulse causes the sarcolemma to become:
For muscle contraction to occur, which energy source must be readily available?
Adenosine triphosphate (ATP)
Under the high power lens of the microscope, the “I bands” of skeletal muscle show as light strips, reflecting the fact that the “I bands” are in an area of:
Actin only (thin)
The “A bands” appear darker because of the presence of
c. both myosin and actin
Which is “rope like”
which is “sheet like”
rope (tendon)
sheet (aponeuroses)
Which attaches to “more movable part of bone”
which attaches to “less movable part of bone”
More Moveable = insertion
Less Movable = origin
What is meant by a “direct” connection of muscle to bone?
epimysium is fused to the periosteum (bone) or to the perichondrium (cartilage)
Steps in the contraction of a muscle
- nerve impulse
- acetylcholine release (ACH)
- action potential through sarcolemma & T-tubules
- Ca2+ release
- troponin changes shape
- tropomysosin moved from active site
- Contraction
What energy molecule is needed to power the cycle of attachment and detachment of the myosin-actin cross-bridges and the removal of Ca2+ by active transport into the sarcoplasmic reticulum?
ATP
