Muscle/Autonomic Nervous System Flashcards
the muscle used for posture and locomotion
Skeletal muscle
The muscle that enables out arms and legs to contract, under our conscious control
Skeletal muscle
The muscle responsible for the rhythmic contractions of the heart
Cardiac muscle
The muscle that causes involuntary contraction in blood vessels, gut, bronchi, and the uterus
Smooth muscle
Muscle is attached at each end to
Tendons
Tendons connect … to …
muscle to bone
Contraction of skeletal muscle pulls on the …. resulting in the …. of the joints
Contraction of skeletal muscle pulls on the tendons resulting in flexion of the joints.
Skeletal muscle is composed of
bundles of long (up to 1 ft) thin cells called muscle fibers.
bundles of long (up to 1 ft) thin cells
muscle fibers.
Mature muscle fibers
long thin cells with many nuclei
appearance of the fiber
striped
Muscle fibers are generated during development by the
fusion of a large number of small precursor cells called myoblasts
small precursor cells of muscle
myoblasts
Each myobast is a single/multi nucleated cell
single
Each muscle fiber is a single/multi nucleated cell
multi
Skeletal muscle fibers consist of
cylindrical bundles called
myofibrils
cylindrical bundles in muscle fibers
myofibrils
The striations within each myofibril are caused by
alternating light I-bands and dark A-bands
I bands
light region of myofibril
A bands
dark region of myofibril
Z-line
dark line in the center of each light band
sarcomere
distance from Z line to Z line
Contractile unit of skeletal muscle
M line
line in the center of each dark band
H zone
region of non overlapping A bands, just thick filament
Each sarcomere consists of two sets of
parallel and partially overlapping protein filaments
thick and thin
(thick/thin) filaments: extending from one end
of the A band to the other
Thick
(thick/thin) filaments: attached to the Z lines and extending across the I band and part way into the A band
Thin
Cross bridges
Attach the thick filaments to the thin filaments
The myofibril is a lattice of thick/thin/both filaments
the myofibril is a lattice of thick and thin filaments.
H Zone has thick/thin/both filaments
thick filaments
I Zone has thick/thin/both filaments
thick filaments
A band has thick/thin/both filaments
both filaments
overlap of thick and thin filaments
Thin filaments are made of
actin
each actin filament is formed from
two chains of globular actin subunits, twisted into a helix.
Thick filaments are made of
myosin
Thicks filaments consist of ______ bundles
myosin bundles
Sliding filament reaction is driven by
ATP hydrolysis
What occurs in the sliding filament model?
The thin filaments are pulled over the thick filaments by the myosin head groups, which repeatedly grab, pull and release the thin filaments.
What occurs when thin filaments slide over thick filaments
the sarcomere contracts
Contraction of the sarcomeres results in
the shortening of the entire myofibril
The amount of tension a muscle fiber can develop depends on
fiber length
length-tension relation reflects
the degree overlap between thick and thin filaments
The cross-bridge cycle is driven by
ATP binding and hydrolysis by the myosin head groups
How does the cross bridge release from the actin?
binding of ATP
Motor unit
A motor neuron and the group of muscle fibers it innervates.
Number of fibers innervated by a single motor neuron
Range from 10 to 100 to several thousand
Muscles with 10 fibers innervated by a single motor neuron
extraocular muscles
Muscles with 100 fibers innervated by a single motor neuron
muscles of the hand
Muscles with several thousand fibers innervated by a single motor neuron
large flexor and extensor muscles of leg
Neuromuscular transmission steps (5)
- Action potential in motor neuron
- Acetylcholine release at presynaptic terminal.
- Na+ influx through activated nicotinic acetylcholine receptors.
- Endplate potential.
- Fiber action potential
size of the motor synapse vs brain synpase
Motor synapse are much larger than brain synpase
What does. the action potential cause muscle to do?
contract