Parasympathetic and sympathetic axons extend from the ______ to the heart.

• A. skeletal muscles
• B. central nervous system
• C. endocrine glands
• D. lymphatic vessels

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the role of the parasympathetic and sympathetic nervous systems. These are divisions of the autonomic nervous system, which controls involuntary functions such as heart rate, digestion, and respiratory rate.
2. Step 2: Recall that both parasympathetic and sympathetic axons originate from the central nervous system (CNS). The CNS includes the brain and spinal cord, which serve as the control centers for autonomic functions.
3. Step 3: Note that skeletal muscles are controlled by the somatic nervous system, not the autonomic nervous system, and are therefore not involved in this process.
4. Step 4: Recognize that endocrine glands and lymphatic vessels are not the origin points for parasympathetic and sympathetic axons. These structures are influenced by the autonomic nervous system but do not serve as the source of its axons.
5. Step 5: Conclude that the correct answer is 'central nervous system,' as it is the origin of parasympathetic and sympathetic axons extending to the heart to regulate its activity.