Nervous System Tissue: Chapter 11

Overview of the Nervous System

The nervous system is a complex network responsible for coordinating the body's activities by transmitting signals to and from different parts of the body. It is essential for sensation, integration, and response to stimuli.

• Central Nervous System (CNS): Consists of the brain and spinal cord; serves as the main control center for processing information.

• Peripheral Nervous System (PNS): Includes all neural tissue outside the CNS; connects the CNS to limbs and organs.

Nervous System Organization

The nervous system is organized into structural and functional divisions, each with specific roles in communication and control.

• CNS: Brain and spinal cord; integrative and control centers.

• PNS: Cranial nerves and spinal nerves; communication lines between the CNS and the rest of the body.

Functions of the Nervous System

The nervous system performs three primary functions: sensory input, integration, and motor output. These functions work together to maintain homeostasis and respond to environmental changes.

• Sensory Input: Detects changes in the internal and external environment using sensory receptors and neurons. This information is sent to the CNS via the afferent division.

• Integration: The CNS processes and interprets sensory input, determining the appropriate response. This function is performed by interneurons within the CNS.

• Motor Output: The CNS sends signals through the efferent division to effectors (muscles or glands) to produce a response.

Example: Seeing a glass of water (sensory input), the brain processes the information (integration), and the arm muscles contract to pick up the glass (motor output).

Key Terms and Definitions

• Neuron: The basic structural and functional unit of the nervous system, specialized for transmitting electrical impulses.

• Neuroglia (Glial Cells): Supporting cells in the nervous system that provide structural and metabolic support to neurons.

• Afferent: Conducting or conveying toward a center (e.g., sensory neurons carrying information to the CNS).

• Efferent: Conducting or conveying away from a center (e.g., motor neurons carrying commands from the CNS to effectors).

• Integration: The process of combining sensory input, processing it, and formulating a response.

Summary Table: Nervous System Divisions and Functions

Additional info:

• The autonomic nervous system (ANS) is further divided into sympathetic and parasympathetic divisions, which have opposing effects on organ systems (e.g., sympathetic increases heart rate, parasympathetic decreases it).

• Neurons communicate via electrical impulses and chemical neurotransmitters at synapses.