Muscles Flashcards
this type of muscle is multinucleated, contains mitochandria, is mainly voluntary, and its basic contractile unit is a sarcomere
skeletal muscle
true or false- the number of skeletal muscle fibers is set before you are born
true
enlargement of existing muscle fibers
hypertrophy
shrinkage of existing muscle fibers
atrophy
these two hormones stimulate hypertrophy
testosterone and GH
This motor protein makes up thick filaments
myosin
what are the 3 components of thin filaments in skeletal muscle?
actin
troponin
tropomyosin
what are the 3 subunits of troponin?
T- attaches to tropomyosin
I- inhibits binding of actin and myosin
C- binds calcium
These are two structure proteins in skeletal muscle that hold the filaments together and anchor them to the cell membrane
titin and dystrophin
what is the basic contractile units of skeletal muscle?
sarcomere
This is a voltage sensor in skeletal muscle that activates ryanodine receptors, allowing Ca2+ release
dihydropyridine (DHP)
this receptor forms a Ca2+ channel
Ryanodine receptor
What part of the thin filament blocks myosin from binding actin?
tropomyosin
________ occurs when Ca2+ is pumped back into the SR
relaxation
at neuromusclular junctions, motor neurons release ________ and it attaches to _______ ____ receptors
ACh; nicotinic ACh
this results from a single AP resulting in a fixed amount of Ca2+ release
twitch
this occurs due to a sustained contraction because of the repeated firing of a motor neuron
tetanus
this type of contraction occurs when the muscle contracts but does not shorten
isometric
this type of contraction occurs when the muscle changes length but the force remains the same
isotonic
This type of muscle is spindle-shaped, can divide throughout the lifetime, has a single nucleus and lacks troponin
smooth muscle
This type of muscle’s thin filaments are anchored to the plasma membrane or to dense bodies
smooth muscle
This is the molecule that Ca2+ binds to in smooth muscle
calmodulin
what molecule does calcium calmodulin activate?
myosin light chain kinase (MLCK)
What is the function of MLCK in smooth muscle?
phosphorylation of myosin, which allows the binding to actin
What enzyme is responsible for the dephosphorylation of myosin in smooth muscle?
myosin light-chain phosphatase (MLCP)
