뒤로Fundamentals of the Nervous System and Nervous Tissue
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Chapter 11: Fundamentals of the Nervous System and Nervous Tissue
Overview of the Nervous System
The nervous system is the master controlling and communicating system of the body. It is responsible for integrating sensory input, coordinating bodily functions, and facilitating rapid communication between different body regions.
Central Nervous System (CNS): Consists of the brain and spinal cord. It acts as the integration and command center.
Peripheral Nervous System (PNS): Composed of cranial nerves, spinal nerves, and ganglia. It connects the CNS to limbs and organs.
Example: The CNS processes information received from the PNS and sends out instructions for movement or response.
Structure of a Typical Neuron
Neurons are the basic structural and functional units of the nervous system. They are specialized for the conduction of electrical impulses.
Cell Body (Soma): Contains the nucleus and is the metabolic center of the neuron.
Dendrites: Short, branched processes that receive signals from other neurons and convey them toward the cell body.
Axon: A long process that transmits impulses away from the cell body to other neurons or effector cells.
Axon Hillock: The cone-shaped region of the cell body where the axon originates; important in the initiation of nerve impulses.
Myelin Sheath: A fatty layer that covers some axons, increasing the speed of impulse transmission.
Axon Terminals: The distal endings of the axon where neurotransmitters are released.
Example: Sensory neurons transmit information from sensory receptors to the CNS, while motor neurons carry instructions from the CNS to muscles.
CNS Versus PNS Terminology
Specific terms are used to describe similar structures in the CNS and PNS. Understanding these distinctions is essential for accurate communication in neuroanatomy.
TERM | DEFINITION |
|---|---|
Nucleus | A collection of neuron cell bodies in the CNS |
Ganglion | A collection of neuron cell bodies in the PNS |
Tract | A bundle of axons in the CNS |
Nerve | A bundle of axons in the PNS |
Example: The optic nerve is a PNS structure, while the corticospinal tract is a CNS structure.
Summary
The nervous system is divided into the CNS and PNS, each with distinct structures and functions.
Neurons are highly specialized cells with unique structures for receiving, processing, and transmitting information.
Terminology differs between the CNS and PNS for similar anatomical features, such as nuclei vs. ganglia and tracts vs. nerves.
Additional info: These notes are based on introductory slides and images from a standard Anatomy & Physiology textbook, providing foundational knowledge for further study of the nervous system.
