Question

1. The following figure shows that a sensory neuron detects the stimulation and sends a signal to a motor neuron. How does the sensory neuron pass a signal to the motor neuron? Start your answer from action potential propagation along the sensory axon. You want to include detailed steps of neurotransmitter release in your answer. (12 points) 2. What is the neurotransmitter used by the sensory neuron? (1 point) Sensory afferent Muscle sensory receptor Extensor muscle Motorefferent

Answer 1

Answer: 1

Sensory neuron: These are the nerve cells whose function is to convert the stimulus from the organism's external environment into the internal signals that are electrical in nature.

Motor neuron: These are the nerve cells whose function is to transfer the impulses from inside of the body (central nervous system) to the outside.

When the stimulus is given to knee at a particular point, this stimulus is detected by the sensory neuron and it activates the muscle spindle a structure present in the quadriceps muscle( muscles present in thigh). This stimulus from the sensory axon travels to the L3 and L4 nerve roots of the spinal cord. Now this gives chemical signal to the motor neuron by the release of neurotransmitter glutamate. Motor neuron after receiving chemical signal activates the contraction of the quadriceps muscle which in turn extends the lower leg at the knee joint. The stimulus at the sensory neuron also releases the another neurotransmitter namely glycine into motor neuron which pulls back the extended leg by relaxing the muscle.This is how the whole process is completed.

Answer:2

The neurotransmitter used by the sensory neuron is the glutamate.