2.2: Nervous System

The nervous system coordinates body functions through its complex network of nerve cells, enabling sensation and movement. It is divided into two primary parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS is composed of the brain and the spinal cord. The brain acts as the body's control center, processing sensory information and coordinating responses. The spinal cord functions as a major signaling pathway for the brain and the rest of the body.

Extending from the CNS, the PNS reaches the limbs and organs, facilitating communication to the farthest parts of the body. The PNS is branched into the somatic nervous system and the autonomic nervous system.

• The somatic nervous system includes sensory neurons, which convey information from sensory receptors to the CNS, and motor neurons, which relay signals from the CNS to muscles to move. This system allows voluntary control over skeletal muscles and mediates reflex actions.
• The autonomic nervous system monitors involuntary processes, such as breathing, heart rate, digestion, and glandular activity. It is further subdivided into the sympathetic and parasympathetic nervous systems.
• The sympathetic nervous system prepares the body to handle stressful situations through the "fight or flight" response. This involves increasing heart rate, redirecting blood flow to muscles, and releasing stored energy to enhance physical performance and alertness.
• Conversely, the parasympathetic nervous system supports "rest and digest" functions, promoting energy conservation and facilitating maintenance activities like digestion, reducing heart rate, and enabling recovery from stress.

The intricate interaction between the CNS and PNS allows for coordinating complex behaviors and maintaining homeostasis. This dynamic system ensures that the body can adapt to internal and external stimuli, maintaining overall health and functionality.

The nervous system coordinates body functions through its complex network of nerve cells, enabling sensation and movement.

The nervous system has two primary parts: CNS, the central nervous system, and PNS, the peripheral nervous system.

The CNS is composed of the brain, which acts as the body's control center, processing sensory information, and the spinal cord, which relays signals between the brain and other parts of the body.

Extending from the CNS, the PNS reaches the limbs and organs, facilitating communication to the farthest parts of the body.

The PNS is divided into the somatic nervous system, which consists of sensory and motor neurons, and the autonomic nervous system, which controls involuntary processes such as breathing and heart rate.

The ANS can be subdivided into the sympathetic and parasympathetic nervous systems.

The sympathetic system activates the body's response during stress,  known as the "fight or flight" response, by increasing alertness and energy consumption.

The parasympathetic system promotes rest to conserve energy and support normal bodily functions.

• Nervous system – Body system that enables sensation, movement, and internal coordination.
• Central nervous system – Comprises the brain and spinal cord, controls body responses.
• Peripheral nervous system – Connects CNS to limbs and organs, enabling communication.
• Autonomic nervous system – Regulates involuntary processes like heartbeat and digestion.
• Somatic nervous system – Controls voluntary muscle movements and reflexes.

• Define nervous system – Explain its function in coordinating body actions (e.g., nerve cells).
• Contrast CNS vs PNS – Identify structural and functional differences (e.g., central vs peripheral).
• Explore autonomic vs somatic roles – Voluntary vs involuntary control (e.g., nervous control).
• Explain sympathetic and parasympathetic responses – Fight or flight vs rest and digest.
• Apply system functions – How the nervous system adapts to external and internal stimuli.

• What is the nervous system in the human body?
• How do the CNS and PNS differ in structure and role?
• What is the difference between sympathetic and parasympathetic responses?

• Students – Understand how the nervous system integrates sensory input and motor output.
• Educators – Provides a visual aid to teach nervous system structure and function.
• Researchers – Supports foundational learning for neurobiology and physiology studies.
• Science Enthusiasts – Offers insights into how the body maintains control and coordination.