Anatomy & Physiology: The Unity of Form and Function, 7th Edition

Published by McGraw-Hill Education
ISBN 10: 0073403717
ISBN 13: 978-0-07340-371-7

Chapter 12 - Section 12.2 - Study Guide - Assess Your Learning Outcomes - Page 471: 4

Answer

Neurons come in various shapes and structures, and they can be categorized into different types based on their morphology and function. Here are the differences between four common types of neurons—multipolar, bipolar, unipolar, and anaxonic neurons—along with an example of each: 1. **Multipolar Neurons:** - **Structure:** Multipolar neurons have multiple processes extending from the cell body. They typically have one long axon and multiple shorter dendrites. - **Function:** These neurons are the most common type in the central nervous system (CNS) and are responsible for motor function and interneuron communication within the CNS. - **Example:** Pyramidal neurons in the cerebral cortex are multipolar neurons. They play a crucial role in higher cognitive functions like memory and decision-making. 2. **Bipolar Neurons:** - **Structure:** Bipolar neurons have two distinct processes: one axon and one dendrite, with the cell body in between. - **Function:** Bipolar neurons are specialized for sensory functions, particularly in the transmission of sensory information like vision, olfaction (smell), and hearing. - **Example:** Bipolar cells found in the retina of the eye are responsible for relaying visual signals from photoreceptor cells to ganglion cells, which then transmit signals to the brain. 3. **Unipolar Neurons (Pseudounipolar Neurons):** - **Structure:** Unipolar neurons have a single process that extends from the cell body and then splits into two branches, forming a T-shaped structure. The cell body is located off to the side of this process. - **Function:** Unipolar neurons are often sensory neurons, particularly involved in transmitting sensory information from peripheral regions (e.g., skin, muscles) to the CNS. - **Example:** Sensory neurons responsible for conveying touch or pain sensations from the skin to the spinal cord are typically unipolar neurons. 4. **Anaxonic Neurons:** - **Structure:** Anaxonic neurons have multiple processes that do not clearly differentiate into distinct axons and dendrites. They are characterized by their lack of a long, projecting axon. - **Function:** Anaxonic neurons have been somewhat enigmatic, and their precise function is not well understood. They are found in regions of the brain where they may play roles in regulating local circuits and information processing. - **Example:** An example of anaxonic neurons can be found in the retina, where they are involved in lateral inhibition, helping to sharpen the contrast and edges of visual stimuli. These four types of neurons demonstrate the diversity of neuronal structures and functions within the nervous system. Each type has evolved to fulfill specific roles in transmitting and processing information, whether it's for motor control, sensory perception, or local circuitry regulation.

Work Step by Step

Neurons come in various shapes and structures, and they can be categorized into different types based on their morphology and function. Here are the differences between four common types of neurons—multipolar, bipolar, unipolar, and anaxonic neurons—along with an example of each: 1. **Multipolar Neurons:** - **Structure:** Multipolar neurons have multiple processes extending from the cell body. They typically have one long axon and multiple shorter dendrites. - **Function:** These neurons are the most common type in the central nervous system (CNS) and are responsible for motor function and interneuron communication within the CNS. - **Example:** Pyramidal neurons in the cerebral cortex are multipolar neurons. They play a crucial role in higher cognitive functions like memory and decision-making. 2. **Bipolar Neurons:** - **Structure:** Bipolar neurons have two distinct processes: one axon and one dendrite, with the cell body in between. - **Function:** Bipolar neurons are specialized for sensory functions, particularly in the transmission of sensory information like vision, olfaction (smell), and hearing. - **Example:** Bipolar cells found in the retina of the eye are responsible for relaying visual signals from photoreceptor cells to ganglion cells, which then transmit signals to the brain. 3. **Unipolar Neurons (Pseudounipolar Neurons):** - **Structure:** Unipolar neurons have a single process that extends from the cell body and then splits into two branches, forming a T-shaped structure. The cell body is located off to the side of this process. - **Function:** Unipolar neurons are often sensory neurons, particularly involved in transmitting sensory information from peripheral regions (e.g., skin, muscles) to the CNS. - **Example:** Sensory neurons responsible for conveying touch or pain sensations from the skin to the spinal cord are typically unipolar neurons. 4. **Anaxonic Neurons:** - **Structure:** Anaxonic neurons have multiple processes that do not clearly differentiate into distinct axons and dendrites. They are characterized by their lack of a long, projecting axon. - **Function:** Anaxonic neurons have been somewhat enigmatic, and their precise function is not well understood. They are found in regions of the brain where they may play roles in regulating local circuits and information processing. - **Example:** An example of anaxonic neurons can be found in the retina, where they are involved in lateral inhibition, helping to sharpen the contrast and edges of visual stimuli. These four types of neurons demonstrate the diversity of neuronal structures and functions within the nervous system. Each type has evolved to fulfill specific roles in transmitting and processing information, whether it's for motor control, sensory perception, or local circuitry regulation.
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