voltage-gated calcium channels
When an action potential arrives at the axon terminal of a motor neuron, which ion channels open?
chemically gated sodium
Binding of the neurotransmitter causes ________ _____ ________ channels to open in the motor end plate
binding of ATP
What causes the myosin head to disconnect from actin?
hydrolysis of ATP
What energizes the power stroke?
Release of acetylcholine from axon terminals at the neuromuscular junction is an event that _________ excitation-contraction coupling, which begins with "excitation" of the T-tubules.
A muscle that is lengthening while it produces tension is performing a(an) ________ contraction.
to lower objects (such as lowering a book from the shelf, or lowering the barbell during a bench press).
When do we use eccentric contractions?
During _________ contractions muscle lengthens as is generates tension, but not enough force to overcome the load.
The ___________ _________ functions in the storage, release, and reuptake of calcium ions.
A ______ is composed of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum.
Voltage-gated sodium channels play a role in the generation and propagation of _________ _________.
Potassium leak channels are important to the _________ ________ potential of neurons.
A series of proteins that control calcium release.
A triad is composed of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum. How are these components connected?
_______ _______ are bulging sacs of sarcoplasmic reticulum.
What is the name given to the regularly spaced infoldings of the sarcolemma?
what ion is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers?
hydrolysis of ATP
How does the myosin head obtain the energy required for activation?
Cross bridge cycling _____ when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin.
________ are made up of several sarcomeres.
The second, more forceful contraction that occurs before the muscle has completely relaxed is an example of wave __________.
__________ refers to the increased force generated by the activation of increasing numbers of motor units.
load placed on the muscle
Which of the following factors influence the velocity and duration of muscle contraction?
Synaptic vesicles fuse to the plasma membrane of the axon terminal and release acetylcholine.
Calcium entry into the axon terminal triggers which of the following events?
Acetylcholine binds to its receptor in the sarcolemma and triggers the opening of ________-______ ______ channels.
diffusion of Na+ into the muscle fiber
what event is most significant in initiating the "wave of depolarization?"
Contraction of skeletal muscle is controlled by ________ motor neurons.
diffusion of Ca2+ into the axonal terminus
What event directly triggers the exocytosis of neurotransmitter?
so they don't get crushed when the muscle contracts.
why are the nuclei of skeletal muscle on the outside?
TRUE or FALSE: food does NOT digest by gravity.
excitable means it is _______.
irritable means it is _______.
big sheet covering a bunch of muscle.
dense regular connective tissue surrounding entire muscle.
fibrous connective tissue surrounding fasicles (groups of muscle fibers).
fine areolar connective tissue surrounding each muscle fiber.
TRUE or FALSE: the epimysium can cover several muscles.
a thick fascia that connects two muscle bellies like that of the occipitalis and frontalis making the occipitofrontalis.
muscle can attach ______ to bone or ______ by tendons or aponeurosis.
muscle protein that holds onto O2 for muscle cell use.
a _________ is a sac of glycogen
________ is composed of a bunch of glucose. EX. multiple beads make necklace. Pop off a bead as needed.
TRUE or FALSE: myofibrils are NOT cells.
dark A bands and light I bands
what gives skeletal muscle striations?
densely packed, rodlike elements.
thick filaments are __ bands.
thin filaments are __ bands.
the __ disc is a sheet of proteins that anchors the thin filaments and connects myofibrils to one another.
the __ zone is the lighter midregion where filaments do not overlap.
the __ line is a line of protein myomesin that holds adjacent thick filaments together.
name the protein in the M line.
heavy polypeptide chains
myosin tails contain 2 interwoven, ______ ___________ ______.
light polypeptide chains
myosin heads contain 2 smaller, ______ _____________ _______ that act as cross bridges during contraction.
ATP binds to the myosin _____.
TRUE or FALSE: actin has no head or tail.
__ actin bears active sites for myosin head attachment during contraction.
__ actin consists of G actin subunits. Also called fibrous actin.
TRUE or FALSE: troponin is bound to tropomyosin not to actin.
TRUE or FALSE: the SR is in contact with every myofibril so it is present when the muscle needs to contract.
what takes the action potential from the nerve to the cell?
t tubule proteins are _______ sensors.
SR foot proteins are gated channels that regulate ______ release from the SR cisternae.
TRUE or FALSE: just because there is contraction that does not mean there is shortening.
skeletal muscles are stimulated by ________ motor neurons.
axon terminal and muscle fiber are separated by a gel-filled space called the ________ _____.
TRUE or FALSE: in the generation of an action potential Na+ moves into the cell until it reaches the threshold. At that point the muscle contracts. It is all or none--like firing a gun. It only takes 1 force.
in ___________ Na+ channels close and voltage-gated K+ channels open.
TRUE or FALSE: during repolarization that muscle cannot contract.
what is the threshold number of muscle?
what is the resting number of muscle?
the ______ period is the time between AP initiation and the beginning of contraction.
it changes shape
what does voltage-sensitive tubule protein mean?
Ca2+ and ATP
What 2 things are required for cross bridge cycling?