Skeletal Muscle Physiology 1 Flashcards
physiological functions of skeletal muscle?
posture maintenace respiratory movement heat production metabolism movement
what innervates skeletal muscle?
somatic nervous system
why are cardiac and smooth muscles involuntary?
are innervated by the autonomic nervous system
what initiates skeletal muscle contraction
neurogenic initiation
what initiates cardiac muscle contraction
myogenic initiation (pacemaker potential)
why does cardiac muscle not contain a neuromuscular junction
not dependent on somatic innervation; has gap junctions instead
which muscle type is most dependent on calcium from the sarcoplasmic reticulum for excitation contraction coupling?
skeletal
what is the name of the transmitter at the neuromuscular junction
acetylcholine
how are skeletal muscle fibres arranged?
in motor units
what is a motor unit
single alpha motor neuron and all the skeletal muscles it innervates
what would a motor unit with few muscle fibres suggest about the muscle itself?
muscle that is serving a fine movement eg eye or muscles of facial expression
what kind of muscle would have thousands of muscle fibres to one motor unit?
thigh muscles
which of actin and myosin appears lighter in the sarcomere?
actin
how is skeletal muscle typically attached to the skeleton?
via tendons
what is a functional unit of an organ?
the smallest component capable of performing all the functions of that organ
what is the functional unit of skeletal muscle?
sarcomere
between which “lines” is the sarcomere found?
Z lines
what is the A band?
basically the length of the sarcomere
what is the H zone?
area between actin filaments in a sarcomere
what is the M line
the vertical line down a middle of the sarcomere
what is the I band?
remaining portions of actin that don’t project in the A band
what are the 2 requirements for muscle contraction to happen?
ATP and calcium
when is Ca released in skeletal muscle?
when the surface action potential spreads down the transverse tubules (v close to sarcoplasmic reticulum)
why is Ca needed in skeletal muscle
to switch on cross bridge formation and allow contraction
