Chapter 5 - Section 5.4 - Study Guide - Assess Your Learning Outcomes - Page 173: 3

Neurons are the fundamental structural and functional units of the nervous system. They have a unique and specialized structure that allows them to transmit electrical signals (action potentials) over long distances. The general structure of a neuron consists of several key components: 1. **Cell Body (Soma)**: - The cell body is the main part of the neuron. - It contains the cell's nucleus and various organelles, including the endoplasmic reticulum and Golgi apparatus, which are essential for protein synthesis and cell maintenance. 2. **Dendrites**: - Dendrites are branching extensions that extend from the cell body. - They are typically shorter and more numerous than the axon. - Dendrites receive incoming signals and transmit them toward the cell body. - These structures play a crucial role in integrating information from other neurons and sensory receptors. 3. **Axon**: - The axon is a long, slender projection that extends from the cell body. - It is responsible for transmitting the electrical signal (action potential) away from the cell body to other neurons, muscles, or glands. - The axon is often covered by a myelin sheath, which consists of multiple layers of a fatty substance called myelin. Myelin insulates the axon and speeds up the conduction of electrical impulses. 4. **Axon Hillock**: - The axon hillock is the junction between the cell body and the axon. - It plays a critical role in initiating the action potential, as it contains a high concentration of voltage-gated ion channels. 5. **Axon Terminals (Terminal Boutons)**: - At the end of the axon, there are numerous fine branches called axon terminals or terminal boutons. - Axon terminals are responsible for transmitting the neuron's signal to other neurons or effector cells (such as muscle fibers or gland cells) through structures called synapses. 6. **Synapses**: - Synapses are specialized junctions between the axon terminals of one neuron and the dendrites or cell body of another neuron or an effector cell. - At the synapse, the neuron communicates with other cells by releasing neurotransmitters, which can either excite or inhibit the activity of the receiving cell. 7. **Myelin Sheath (in some neurons)**: - Some axons are surrounded by a myelin sheath, which is formed by specialized glial cells called oligodendrocytes in the central nervous system (CNS) and Schwann cells in the peripheral nervous system (PNS). - The myelin sheath insulates the axon and allows for faster and more efficient propagation of the action potential. Overall, the unique structure of neurons, with their dendrites, cell body, axon, and synapses, enables them to transmit and process information in the form of electrical signals, facilitating the communication and coordination of activities within the nervous system.

Neurons are the fundamental structural and functional units of the nervous system. They have a unique and specialized structure that allows them to transmit electrical signals (action potentials) over long distances. The general structure of a neuron consists of several key components: 1. **Cell Body (Soma)**: - The cell body is the main part of the neuron. - It contains the cell's nucleus and various organelles, including the endoplasmic reticulum and Golgi apparatus, which are essential for protein synthesis and cell maintenance. 2. **Dendrites**: - Dendrites are branching extensions that extend from the cell body. - They are typically shorter and more numerous than the axon. - Dendrites receive incoming signals and transmit them toward the cell body. - These structures play a crucial role in integrating information from other neurons and sensory receptors. 3. **Axon**: - The axon is a long, slender projection that extends from the cell body. - It is responsible for transmitting the electrical signal (action potential) away from the cell body to other neurons, muscles, or glands. - The axon is often covered by a myelin sheath, which consists of multiple layers of a fatty substance called myelin. Myelin insulates the axon and speeds up the conduction of electrical impulses. 4. **Axon Hillock**: - The axon hillock is the junction between the cell body and the axon. - It plays a critical role in initiating the action potential, as it contains a high concentration of voltage-gated ion channels. 5. **Axon Terminals (Terminal Boutons)**: - At the end of the axon, there are numerous fine branches called axon terminals or terminal boutons. - Axon terminals are responsible for transmitting the neuron's signal to other neurons or effector cells (such as muscle fibers or gland cells) through structures called synapses. 6. **Synapses**: - Synapses are specialized junctions between the axon terminals of one neuron and the dendrites or cell body of another neuron or an effector cell. - At the synapse, the neuron communicates with other cells by releasing neurotransmitters, which can either excite or inhibit the activity of the receiving cell. 7. **Myelin Sheath (in some neurons)**: - Some axons are surrounded by a myelin sheath, which is formed by specialized glial cells called oligodendrocytes in the central nervous system (CNS) and Schwann cells in the peripheral nervous system (PNS). - The myelin sheath insulates the axon and allows for faster and more efficient propagation of the action potential. Overall, the unique structure of neurons, with their dendrites, cell body, axon, and synapses, enables them to transmit and process information in the form of electrical signals, facilitating the communication and coordination of activities within the nervous system.