Chapter 13 - Section 13.1 - Study Guide - Assess Your Learning Outcomes - Page 504: 8

The organization of spinal gray and white matter in cross-sections of the spinal cord is a distinctive feature of the central nervous system. The spinal cord consists of both gray and white matter, which serve different functions and are named based on their appearance. **1. Gray Matter:** - **Location**: Gray matter is found in the center of the spinal cord and appears as a butterfly or H-shaped region when viewed in cross-section. - **Composition**: Gray matter consists primarily of cell bodies of neurons, dendrites, glial cells, and unmyelinated axons. It is rich in neural cell bodies, giving it a grayish appearance under a microscope. - **Function**: Gray matter is responsible for processing and integrating sensory information, as well as initiating motor responses. It contains interneurons and motor neurons that transmit signals within the spinal cord and between the spinal cord and the brain. Sensory input is received in the dorsal (posterior) gray horns, while motor output is generated in the ventral (anterior) gray horns. **2. White Matter:** - **Location**: White matter surrounds the gray matter in the spinal cord and appears as a white, outer region. - **Composition**: White matter is primarily composed of myelinated axons, which are long nerve fibers covered in myelin sheaths. Myelin is a fatty substance that gives the axons a whitish appearance. - **Function**: White matter serves as a communication highway, transmitting signals between different regions of the spinal cord and between the spinal cord and the brain. It contains ascending (sensory) and descending (motor) tracts that carry sensory information from the periphery to the brain and motor commands from the brain to the muscles and glands. The terms "gray" and "white" matter are derived from the appearance of these regions when viewed in histological sections. Gray matter is darker due to the presence of cell bodies and other cellular components, while white matter appears lighter due to the myelin covering on axons. These color distinctions are also visible when examining the brain and other parts of the central nervous system. In summary, the spinal cord's gray matter is responsible for processing and integrating neural signals, while the white matter facilitates the transmission of signals between different parts of the nervous system. The terms "gray" and "white" matter are descriptive based on their appearance and composition in histological preparations.

The organization of spinal gray and white matter in cross-sections of the spinal cord is a distinctive feature of the central nervous system. The spinal cord consists of both gray and white matter, which serve different functions and are named based on their appearance. **1. Gray Matter:** - **Location**: Gray matter is found in the center of the spinal cord and appears as a butterfly or H-shaped region when viewed in cross-section. - **Composition**: Gray matter consists primarily of cell bodies of neurons, dendrites, glial cells, and unmyelinated axons. It is rich in neural cell bodies, giving it a grayish appearance under a microscope. - **Function**: Gray matter is responsible for processing and integrating sensory information, as well as initiating motor responses. It contains interneurons and motor neurons that transmit signals within the spinal cord and between the spinal cord and the brain. Sensory input is received in the dorsal (posterior) gray horns, while motor output is generated in the ventral (anterior) gray horns. **2. White Matter:** - **Location**: White matter surrounds the gray matter in the spinal cord and appears as a white, outer region. - **Composition**: White matter is primarily composed of myelinated axons, which are long nerve fibers covered in myelin sheaths. Myelin is a fatty substance that gives the axons a whitish appearance. - **Function**: White matter serves as a communication highway, transmitting signals between different regions of the spinal cord and between the spinal cord and the brain. It contains ascending (sensory) and descending (motor) tracts that carry sensory information from the periphery to the brain and motor commands from the brain to the muscles and glands. The terms "gray" and "white" matter are derived from the appearance of these regions when viewed in histological sections. Gray matter is darker due to the presence of cell bodies and other cellular components, while white matter appears lighter due to the myelin covering on axons. These color distinctions are also visible when examining the brain and other parts of the central nervous system. In summary, the spinal cord's gray matter is responsible for processing and integrating neural signals, while the white matter facilitates the transmission of signals between different parts of the nervous system. The terms "gray" and "white" matter are descriptive based on their appearance and composition in histological preparations.