The Neuromuscular Junction

Which structure directly receives acetylcholine released from synaptic vesicles at the neuromuscular junction?

• Myofibril inside muscle fiber

• Schwann cell around axon

• Motor end plate of sarcolemma

• Axon hillock of motor neuron

What best describes the synaptic cleft in the neuromuscular junction?

• Fluid-filled gap between neuron and muscle

• Channel that carries action potentials

• Calcium store inside the muscle fiber

• Insulating sheath around the axon

Match each component to its role at the neuromuscular junction.

• Membrane packets storing neurotransmitter

• Sarcolemma

• Muscle fiber plasma membrane

• Motor end plate

• Region with receptors and folds

• Acetylcholine

• Chemical that diffuses across cleft

• Synaptic vesicles

Which event triggers skeletal muscle fiber contraction at this junction?

• Nucleus of muscle fiber initiates action potential

• Axon branches physically pull on myofibrils

• Mitochondria release ATP into synaptic cleft

• Acetylcholine binds receptors on motor end plate

Which statement about axon branches contacting a single muscle fiber is most accurate?

• Branches wrap entirely around the nucleus

• Branches fuse with mitochondria to release energy

• Branches penetrate the myofibrils directly

• Each branch forms a synaptic cleft with the sarcolemma

Select all structures located within the axon terminal region shown in the diagram. There are 3 correct answers

• Myofibrils

• Synaptic vesicles

• Acetylcholine molecules

• Mitochondria

• Folded sarcolemma

What is this a diagram of?

• Muscle fiber nucleus—inside the axon sheath

• Motor end plate—inside the neuron axon

• Myofibrils—inside the muscle fiber made of actin and myosin

• Sarcolemma—inside the axon terminal

Match each labeled structure to its meaning

• neurotransmitter that fill the synaptic cleft

• Sarcolemma

• a section of the sarcolemma that connects with the motor neuron

• Acetylcholine

• where the motor neuron and muscle meet

• Neuromuscular Junction

• a space between the motor neuron and the sarcolemma

• Synaptic Cleft

• plasma membrane of a muscle cell

• Motor end plate

Which ion triggers acetylcholine release into the synaptic cleft?

• Calcium (Ca²⁺)

• Chloride (Cl^-)

• Potassium (K⁺)

• Sodium (Na⁺)

Name the structures that are responsible for the storage and release of the neurotransmitter acetylcholine at the neuromuscular juntion.

• Neurotransmitter receptors
• Synaptic Cleft

• Motor end plate

• Synaptic vesicles