Which of the following statement describes an autonomic nervous system

Step 1: Analyze the question The question asks which statement correctly describes the autonomic nervous system (ANS).

Step 2: Explain the concept The autonomic nervous system is the part of the peripheral nervous system that controls the involuntary activities of the body. It has two divisions:

• Sympathetic: prepares the body for "fight or flight" (raises heart rate, widens pupils).
• Parasympathetic: "rest and digest" (slows heart rate, promotes digestion).

Its effectors are smooth muscles (e.g. in the gut and blood vessels), cardiac muscle (the heart), and glands. Skeletal muscles are controlled by the somatic nervous system, not the ANS.

Step 3: Evaluate each option

• A. It always stimulates effectors: Wrong. The ANS can stimulate or inhibit. For example, the sympathetic system speeds up the heart, while the parasympathetic slows it down.
• B. Activities are voluntary: Wrong. ANS activities are involuntary, meaning you don't consciously control them.
• C. It deals with external stimuli and their responses: Wrong. This describes the somatic nervous system and the voluntary, conscious reactions to the environment. The ANS mainly regulates the body's internal environment.
• D. It affects glands, cardiac muscles and smooth muscles: Correct. These are exactly the effectors of the ANS.

Step 4: Answer The correct option is D.

Exam tip: Remember "Autonomic = Automatic." It works without your conscious control and handles the heart, gut, glands and blood vessels. If an option says "voluntary" or "skeletal muscle" in an ANS question, you can eliminate it quickly.