Which of the following is an efferent neuron that is responsible for releasing a neurotransmiter that stimulates a muscle cell to contract?
A.
Motor neuron
B.
Interneuron
C.
Sensory neuron
D.
Neuroglia
The correct answer and Explanation is :
The correct answer is A. Motor neuron.
Explanation
Motor neurons are a type of efferent neuron responsible for transmitting signals from the central nervous system (CNS) to peripheral muscles or glands. These neurons play a crucial role in initiating and controlling voluntary and involuntary muscle movements.
Function of Motor Neurons:
- Signal Transmission: Motor neurons carry electrical impulses from the CNS, which includes the brain and spinal cord, to muscle cells. These impulses travel through the neuron’s axon and reach the neuromuscular junction, the synapse between the motor neuron and a muscle fiber.
- Neurotransmitter Release: At the neuromuscular junction, the motor neuron releases a neurotransmitter called acetylcholine (ACh). This chemical messenger crosses the synaptic cleft, the gap between the neuron and the muscle cell, and binds to receptors on the muscle fiber’s membrane.
- Muscle Contraction: The binding of acetylcholine to its receptors causes an influx of sodium ions into the muscle cell, leading to depolarization of the muscle membrane. This depolarization triggers a cascade of events within the muscle cell, ultimately resulting in muscle contraction.
Comparison with Other Neurons:
- Interneurons (B): These neurons are located within the CNS and are primarily involved in processing and relaying information between sensory and motor neurons. They do not directly stimulate muscle cells.
- Sensory Neurons (C): Sensory neurons carry information from sensory receptors towards the CNS. They are involved in detecting stimuli but do not directly cause muscle contractions.
- Neuroglia (D): Neuroglia, or glial cells, provide support and protection for neurons but do not participate in neurotransmission or muscle stimulation.
In summary, motor neurons are essential for muscle movement because they are responsible for transmitting signals from the CNS to muscles, releasing neurotransmitters that induce muscle contraction.