PNS

Definition

The peripheral nervous system (PNS) is the part of the nervous system that lies outside the brain and spinal cord. It connects the central nervous system (CNS) to limbs and organs, serving as a communication network that transmits signals between the CNS and the rest of the body. The PNS is crucial for conveying sensory information to the CNS and executing motor commands from the CNS.

5 Must Know Facts For Your Next Test

1. The PNS is divided into two main parts: the somatic nervous system and the autonomic nervous system, each with distinct functions.
2. The autonomic nervous system is further categorized into sympathetic and parasympathetic systems, which regulate bodily responses during stress and rest, respectively.
3. Peripheral nerves in the PNS can regenerate after injury, unlike nerves in the CNS, making PNS injuries often less severe in terms of long-term effects.
4. Sensory neurons within the PNS carry information from sensory receptors to the CNS, while motor neurons transmit commands from the CNS to muscles and glands.
5. The PNS plays a vital role in reflex actions, allowing for quick responses to stimuli without involving higher brain centers.

Review Questions

• How does the structure of the PNS facilitate its function in communication between the body and the central nervous system?
  • The structure of the PNS includes a vast network of nerves that branch out from the spinal cord and brain to connect with various parts of the body. This extensive network allows for efficient transmission of sensory information from peripheral receptors to the CNS and conveys motor commands from the CNS back to muscles and organs. The diverse types of neurons in the PNS—sensory and motor—work together to ensure smooth communication, enabling rapid responses to environmental changes.
• Evaluate how damage to the PNS can impact bodily functions differently than damage to the CNS.
  • Damage to the PNS often leads to localized deficits such as muscle weakness or loss of sensation in specific areas, but these nerves have a notable ability to regenerate, allowing for recovery over time. In contrast, damage to the CNS can result in more widespread and permanent deficits because nerve cells in this region do not regenerate effectively. This difference highlights how injuries in these two systems can lead to varying levels of functional impairment, with PNS injuries generally offering better prospects for recovery.
• Synthesize how both divisions of the PNS interact with each other to maintain homeostasis in the human body.
  • The two divisions of the PNS—the somatic nervous system and autonomic nervous system—work together intricately to maintain homeostasis within the body. The somatic system controls voluntary actions such as movement, which can influence overall body function, while the autonomic system manages involuntary processes like heart rate and digestion. For example, during physical activity initiated by voluntary movements (somatic), sympathetic responses from the autonomic nervous system increase heart rate and redirect blood flow to muscles. This coordinated effort helps ensure that all bodily systems operate harmoniously under changing conditions.

Related terms

CNS: The central nervous system (CNS) consists of the brain and spinal cord, which integrate and process information from the peripheral nervous system.

Autonomic Nervous System: A division of the PNS that regulates involuntary bodily functions, such as heartbeat and digestion, without conscious control.

Somatic Nervous System: A subdivision of the PNS responsible for voluntary movements and transmitting sensory information to the CNS from the skin, muscles, and joints.