Biology
Answer
An automatic, spontaneous and mechanical response to a stimulus controlled by the spinal cord without the involvement of the brain is called a reflex action.
The path that an impulse takes in a reflex action is called a reflex arc. The reflex arc involves three neurons — sensory neurons, association neurons and motor neurons.
- If we touch a hot object, a stimulus triggers an impulse in a receptor on the skin.
- The impulse then travels from the receptor through a sensory neuron to the spinal cord.
- In the spinal cord, it passes through an association neuron to a motor neuron and finally reaches the muscles.
- The muscles of the effector organ contract moving it away from the hot object.
Below flow chart shows a simple reflex action of immediate withdrawal of hand on touching a hot object:
Related Questions
Explain the structure of a motor nerve cell with the help of a diagram.
Describe the human central nervous system along with its parts and functions.
The diagram represents the external view of the human brain. Study it and then answer the questions that follow.
- Name the parts numbered a to d.
- What is the main function of the parts numbered c and d?
The diagram shows a reflex arc. Study it and answer the following questions.
- Name the parts numbered a to d.
- Using the letters of alphabet shown in the diagram, indicate the direction in which the impulse enters and leaves part c. X to Y or Y to X?
- What is reflex action?
- With the help of a flow chart, show a simple reflex action.
