Practice Set 3A Flashcards
What are the functions of skeletal muscle?
Heat production
Blood sugar regulation
Control of body openings and passages
The endomysium is a connective tissue sheath that wraps around which of the following?
Muscle fiber
Which describes a muscle fascicle?
A bundle of muscle fibers surrounded by connective tissue
Which term refers to the loose connective tissue layer that surrounds skeletal muscle fascicles?
Perimysium
The structures indicated by the arrows are examples of which of the following?
Tendons
Which are functions of skeletal muscle?
Heat production
Movement
Joint stability
Which describes the endomysium?
A loose connective tissue layer around each individual muscle cell
Which term refers to bundles of muscle fibers, wrapped in connective tissue, within a muscle?
Fascicles
What is the perimysium?
A connective tissue sheath bundling many muscle fibers into a fascicle
In flexing the elbow, the prime mover is the ______.
brachialis
Connective tissue structures that attach bone to muscle are called _____.
tendons
Because skeletal muscle is under the conscious control it is said to be ______.
voluntary
Muscle cells contain _______ a red pigment that stores oxygen needed for muscular activity.
myoglobin
In a myofibril, a thick filament is composed of pairs of _______ molecules intertwined together.
myosin
Which term refers to a muscle that produces most of the force during a particular joint action?
Agonist
Skeletal muscle exhibits alternating light and dark bands called _______.
striations
The portion of a myofibril from one Z disc to the next is called a(n) _________.
sarcomere
True or false: Skeletal muscle contraction helps produce body heat.
True
What is a motor unit?
All of the muscle fibers innervated by a single motor nerve fiber
Muscle cells contain _______, a starch-like carbohydrate that provides energy during intense exercise.
glycogen
Which protein makes up the thick filaments of a myofibril?
Myosin
A synapse is the point where a nerve fiber meets a target cell. When the target cell is a muscle fiber, this type of synapse is called a _______ junction.
neuromuscular
What is the prime mover?
agonist
Within skeletal muscle cells, what extends from one Z disc to the next and constitutes one contractile unit?
Sarcomere
All of the muscle fibers innervated by a single nerve fiber constitute a ______ unit.
motor
What is the indented region of the sarcolemma that participates in the neuromuscular junction called?
Motor end plate
Muscle cells contain _______ , a red pigment that stores oxygen needed for muscular activity.
myoglobin
The synaptic knob does not touch the muscle fiber but is separated by which structure?
Synaptic cleft
What is a neuromuscular junction?
A site where a nerve fiber communicates with a muscle fiber
Which term refers to a muscle that produces most of the force during a particular joint action?
Agonist
Within a synapse, a neuron ends in a swelling called a(n) ______ terminal.
synaptic, axon, Axon, or Synaptic
A synapse is the point where a nerve fiber meets a target cell. When the target cell is a muscle fiber, this type of synapse is called a _______ junction.
neuromuscular
What is acetylcholine?
The neurotransmitter released at a neuromuscular junction
In flexing the elbow, the prime mover is the ______.
brachialis
Regarding skeletal muscle contraction, what is excitation?
The process by which action potentials in a nerve fiber lead to action potentials in a muscle fiber
At the synaptic knob of the motor neuron, calcium stimulates exocytosis of the synaptic vesicles to release the neurotransmitter ______ into the synapse.
acetylcholine
What is the indented region of the sarcolemma that participates in the neuromuscular junction called?
Motor end plate
The synaptic knob does not touch the muscle fiber but is separated by which structure?
Synaptic cleft
The neurotransmitter used in a neuromuscular junction is ______.
acetylcholine
What is the process by which action potentials of a nerve fiber lead to action potentials in the muscle fiber called?
Excitation
When a nerve signal arrives at a synaptic knob, which voltage-gated channels open in the knob?
Calcium
In an NMJ, after acetylcholine diffuses across the synaptic cleft, where does it bind to ligand-gated channels?
On the sarcolemma
Within a synapse, a neuron ends in a swelling called a(n) ________ terminal.
axon
What is excitation-contraction coupling?
The events that link the action potential of the sarcolemma to the activation of the myofilament contraction
Action potentials spread across the sarcolemma and continue down which structures into the sarcoplasm?
T tubules
Regarding skeletal muscle contraction, what is excitation?
The process by which action potentials in a nerve fiber lead to action potentials in a muscle fiber
When acetylcholine binds to its receptors on the motor end plate, an ion channel opens and ______ ions diffuse quickly into the muscle cell.
sodium
Which phase of contraction links the action potential in the sarcolemma to the activation of the myofilament?
Excitation-contraction coupling
Action potentials cause the opening of voltage-gated sodium ion channels in the ________ tubules. This leads to the opening of calcium ion channels in the terminal cisternae of the sarcoplasmic reticulum.
transverse
What is the process by which action potentials of a nerve fiber lead to action potentials in the muscle fiber called?
Excitation
What must occur before tropomyosin can shift, revealing the active sites that allow myosin heads to bind to the actin filaments?
Calcium must bind to troponin.
When a nerve signal arrives at a synaptic knob, which voltage-gated channels open in the knob?
Calcium
During which phase of muscle contraction is calcium transported back into the cisternae and tropomyosin moves back to block the actin active sites?
Relaxation
In an NMJ, after acetylcholine diffuses across the synaptic cleft, where does it bind to ligand-gated channels?
On the sarcolemma
What is excitation-contraction coupling?
The events that link the action potential of the sarcolemma to the activation of the myofilament contraction
The enzyme that breaks down acetylcholine is called
acetylcholinesterase, AChE, or cholinesterase
Action potentials spread across the sarcolemma and continue down which structures into the sarcoplasm?
T tubules
What occurs when calcium binds to troponin?
The troponin-tropomyosin complex changes shape and exposes the myosin binding sites (active sites).
Steps of muscle relaxation in order.
What is the role of acetylcholinesterase?
It breaks down ACh, ending muscle stimulation.
During relaxation, active-transport pumps in the sarcoplasmic reticulum move which ion from the sarcoplasm into the cisternae?
Calcium
During which phase of muscle contraction is calcium transported back into the cisternae and tropomyosin moves back to block the actin active sites?
Relaxation
