11.REFLEX ACTION AND REFLEX ARC

Reflex action

The involuntary response to a peripheral nervous stimulation that occurs without conscious effort or thought and involves the central nervous system.

Reflex pathway

The series of neurons involved in a reflex action, including at least one afferent neuron (receptor) and one efferent neuron (effector or excitor) arranged in a specific order.

Afferent neuron

The neuron that receives signals from a sensory organ and transmits the impulse via a dorsal nerve root into the central nervous system (at the level of the spinal cord).

Efferent neuron

The neuron that carries signals from the central nervous system to the effector.

Reflex arc

The pathway followed by the stimulus and response in a reflex action, involving the afferent neuron, central nervous system, and efferent neuron.

Reflex action

The entire process of response to a peripheral nervous stimulation that occurs involuntarily, i.e., without conscious effort or thought and requires the involvement of a part of the central nervous system is called a ________.

Afferent neuron

The reflex pathway comprises at least one ________ (receptor) appropriately arranged in a series.

Efferent neuron

The reflex pathway comprises at least one afferent neuron (receptor) and one ________ (effector or excitor) neuron appropriately arranged in a series.

Reflex arc

The stimulus and response form a ________ as shown in the knee jerk reflex.

Knee jerk reflex

You should carefully study Figure 21.5 to understand the mechanism of a ________.