Anatomy
thin filaments
Cross bridges are created when myosin heads bind to blank
Acetylcholinesterase
Enzyme that breaks down acetylcholine
synaptic celft
Gao between the axon terminals and the plasma membrane of a neighboring muscle cell
Bind to receptors in the sarcolemma of the muscle cell
In order to excite a muscle cell, acetycholine must ____.
Contractility
Muscle tissue has the ability to shorten when adequetly stimulated, a characteristic, known as blank
sarcoplasmic reticulum
The blank is an organelle that wraps and surrounds the myofibril and stores calcium
True
The effect of the neurotransmitter on the muscle cell membrane is so temporarily modify its permeability of ions such as Na+ and K+
synaptic cleft
The gap between the axon terminal of a motor neuron and the sarcolemma of a skeletal muscle cell is called the blank
synaptic cleft
The gap between the motor neuron and the muscle fiber it supplies as the neuromuscular junction is called the blank
cross bridges
The heads of the myosin myofilaments are called ________ when they link the thick and thin filaments together during skeletal muscle contraction.
a sliding of thin filaments past thick filaments
The mechanical force of contraction is generated by what?
True
The neurotransmitter used by the nervous system to activate skeletal muscle cells is acetylcholine
Calcium ions
The sarcoplasmic reticulum stores the chemical
True
The sarcoplasmic reticulum wraps like a sleeve around the myofibril and stores and releases calcium
False
Thick filaments are made of protein called actin
True
When a muscle fiber contracts, the I band diminish in size, the h zonez disappear, and the A bands move closer together but do not diminish in length
Z discs
When a skeletal muscle is fully contracted, the blank are closer to the thick filaments
Sarcomere
Which of the following can actually shorten during a muscle contraction?
Acetylcholine causes temporary permeability to sodium
Which of these events must occur first to trigger the skeletal muscle to generate an action potential and contract?
thick filaments
Which one of the following is composed of myosin protein?
calcium triggers the binding of myosin to actin
Why are calcium ions necessary for skeletal muscle contraction?
motor unit
A motor neuron and all of the skeletal muscle cells it stimulates are termed a blank
False
A muscle twitch results when the muscle is stimulated so rapidly that no evidence of relaxation is seen
False
A neuromuscular junction consist of one neuron and all the skeletal muscles it stimulates
The contractile unit between two z discs
A sarcomere is:
The muscle twitch is a brief but jerky movement, which the tetanic contraction is prolonged and continuous
A skeletal muscle twitch differs from a tetanic contraction in that blank
Fused, or complete, tetanus
A smooth, sustained contraction is called ________.
A neurotransmitter that stimulates skeletal muscle
Acetylcholine is blank
sarcoplasmic reticulum
An elaborate and specialized network of membranes in skeletal muscle cells that function in calcium storage is the blank
action potential
Electric current that travels the length of the muscle
Sodium ions
Chemical that enters a muscle cell upon excitation
actin filaments
During skeletal muscle contraction, myosin heads attach to binding sites associated with ________.
Axon terminals of the motor neuron
Neurotransmitters are released upon stimulation from a nerve impulse by the blank
Motor unit
One neuron and all the skeletal muscles it stimulates is known as a blank
Acetylcholine
Specific neurotransmitter that stimulates skeletal muscle cells