Automatic response to a stimulus not controlled by brain

Automatic response to a stimulus not controlled by brain

• A. White matter
• B. Hormone
• C. Reflex action
• D. Neuron

Answer: (C)

An automatic, rapid response to a stimulus that doesn’t involve conscious thought is a reflex action. This happens through a reflex arc, where a stimulus is detected by receptors and the impulse travels along a sensory neuron to the spinal cord. There, usually via an interneuron, the signal is passed to a motor neuron, which stimulates an effector such as a muscle to contract. Because the processing occurs largely in the spinal cord with few synapses and often without involving the brain, the reaction is fast and not under voluntary control. White matter is just bundles of nerve fibers, not an action. Hormones are chemical signals that travel through the bloodstream and produce slower, widespread effects, not the immediate, local response of a reflex. A neuron is the cell that transmits signals, but the term for the actual automatic response is reflex action.

An automatic, rapid response to a stimulus that doesn’t involve conscious thought is a reflex action. This happens through a reflex arc, where a stimulus is detected by receptors and the impulse travels along a sensory neuron to the spinal cord. There, usually via an interneuron, the signal is passed to a motor neuron, which stimulates an effector such as a muscle to contract. Because the processing occurs largely in the spinal cord with few synapses and often without involving the brain, the reaction is fast and not under voluntary control.

White matter is just bundles of nerve fibers, not an action. Hormones are chemical signals that travel through the bloodstream and produce slower, widespread effects, not the immediate, local response of a reflex. A neuron is the cell that transmits signals, but the term for the actual automatic response is reflex action.