Chapter 5 - Section 5.4 - Study Guide - Assess Your Learning Outcomes - Page 173: 2

Nervous tissue, found in the central nervous system (CNS) and peripheral nervous system (PNS), consists of two basic types of cells: neurons and glial cells (neuroglia). These cells have distinct functions within the nervous system: 1. **Neurons**: - **Function**: Neurons are the primary functional units of the nervous system. They are responsible for transmitting electrical signals and information throughout the body. - **Key Characteristics**: - **Excitability**: Neurons are highly excitable cells. They can generate and propagate electrical signals known as action potentials. - **Longevity**: Neurons are typically long-lived cells and can function for a person's entire lifetime. - **Amitotic**: Most neurons are amitotic, meaning they do not undergo cell division to replace damaged or lost neurons. Exceptions include some neurons in the PNS. - **Structure**: - Neurons consist of a cell body (soma), dendrites, and an axon. - The cell body contains the nucleus and most of the cell's organelles. - Dendrites receive incoming signals from other neurons or sensory receptors. - The axon transmits signals away from the cell body to other neurons or effector cells (e.g., muscles or glands). - **Functionality**: - Neurons receive signals at their dendrites, integrate these signals in the cell body, and transmit the resulting signal as an action potential down the axon. - The synapse is the junction where neurons communicate with each other or with target cells, such as muscles or glands, by releasing neurotransmitters. 2. **Glial Cells (Neuroglia)**: - **Function**: Glial cells provide support, protection, and maintenance for neurons. They play crucial roles in maintaining the overall health and function of the nervous system. - **Key Characteristics**: - **Non-Excitable**: Glial cells do not generate or transmit electrical signals like neurons. - **Abundance**: Glial cells outnumber neurons in the nervous system. - **Mitotic**: Most glial cells are capable of mitosis, meaning they can divide to produce new glial cells when necessary. - **Types of Glial Cells**: - **Astrocytes**: These cells provide physical and metabolic support to neurons, regulate the chemical composition of the extracellular fluid, and help form the blood-brain barrier. - **Oligodendrocytes (in CNS) and Schwann Cells (in PNS)**: These cells produce myelin, a fatty substance that insulates axons, allowing for faster electrical signal transmission. - **Microglia**: These are the immune cells of the CNS and are responsible for immune defense and maintenance of tissue homeostasis. - **Ependymal Cells**: These cells line the ventricles of the brain and assist in the production and circulation of cerebrospinal fluid. - **Functionality**: - Glial cells provide physical and metabolic support to neurons, maintain the ionic and chemical environment around neurons, and play roles in immune responses and repair. In summary, neurons are the specialized excitable cells responsible for transmitting electrical signals and information, while glial cells provide essential support and protection for neurons and maintain the overall health of the nervous system. Together, these two types of cells work in concert to enable the complex functions of the nervous system.

Nervous tissue, found in the central nervous system (CNS) and peripheral nervous system (PNS), consists of two basic types of cells: neurons and glial cells (neuroglia). These cells have distinct functions within the nervous system: 1. **Neurons**: - **Function**: Neurons are the primary functional units of the nervous system. They are responsible for transmitting electrical signals and information throughout the body. - **Key Characteristics**: - **Excitability**: Neurons are highly excitable cells. They can generate and propagate electrical signals known as action potentials. - **Longevity**: Neurons are typically long-lived cells and can function for a person's entire lifetime. - **Amitotic**: Most neurons are amitotic, meaning they do not undergo cell division to replace damaged or lost neurons. Exceptions include some neurons in the PNS. - **Structure**: - Neurons consist of a cell body (soma), dendrites, and an axon. - The cell body contains the nucleus and most of the cell's organelles. - Dendrites receive incoming signals from other neurons or sensory receptors. - The axon transmits signals away from the cell body to other neurons or effector cells (e.g., muscles or glands). - **Functionality**: - Neurons receive signals at their dendrites, integrate these signals in the cell body, and transmit the resulting signal as an action potential down the axon. - The synapse is the junction where neurons communicate with each other or with target cells, such as muscles or glands, by releasing neurotransmitters. 2. **Glial Cells (Neuroglia)**: - **Function**: Glial cells provide support, protection, and maintenance for neurons. They play crucial roles in maintaining the overall health and function of the nervous system. - **Key Characteristics**: - **Non-Excitable**: Glial cells do not generate or transmit electrical signals like neurons. - **Abundance**: Glial cells outnumber neurons in the nervous system. - **Mitotic**: Most glial cells are capable of mitosis, meaning they can divide to produce new glial cells when necessary. - **Types of Glial Cells**: - **Astrocytes**: These cells provide physical and metabolic support to neurons, regulate the chemical composition of the extracellular fluid, and help form the blood-brain barrier. - **Oligodendrocytes (in CNS) and Schwann Cells (in PNS)**: These cells produce myelin, a fatty substance that insulates axons, allowing for faster electrical signal transmission. - **Microglia**: These are the immune cells of the CNS and are responsible for immune defense and maintenance of tissue homeostasis. - **Ependymal Cells**: These cells line the ventricles of the brain and assist in the production and circulation of cerebrospinal fluid. - **Functionality**: - Glial cells provide physical and metabolic support to neurons, maintain the ionic and chemical environment around neurons, and play roles in immune responses and repair. In summary, neurons are the specialized excitable cells responsible for transmitting electrical signals and information, while glial cells provide essential support and protection for neurons and maintain the overall health of the nervous system. Together, these two types of cells work in concert to enable the complex functions of the nervous system.