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 6 - Section 6.2 - Study Guide - Assess Your Learning Outcomes - Page 199: 10

Answer

Fingernails and toenails are composed of layers of a protein called keratin and serve to protect the sensitive tips of our fingers and toes. Here's an overview of their anatomy, the location of their growth zone, and the typical rate of nail growth: **Anatomy of Fingernails and Toenails:** 1. **Nail Plate:** This is the visible, hard part of the nail that extends beyond the fingertip or toe. It is composed of tightly packed layers of dead, flattened, and fully keratinized nail cells. 2. **Nail Bed:** The nail bed is the tissue beneath the nail plate. It is rich in blood vessels and helps nourish the growing nail. 3. **Lunula:** The lunula is the crescent-shaped, whitish area at the base of the nail, visible on some but not all nails. It is the visible part of the nail matrix. 4. **Nail Matrix:** The nail matrix is located beneath the base of the nail and extends under the cuticle (eponychium). It is the tissue responsible for producing new nail cells, and it plays a crucial role in nail growth. 5. **Cuticle (Eponychium):** The cuticle is the thin layer of tissue that covers the base of the nail, protecting the nail matrix from external elements and potential infections. **Location of the Growth Zone:** The growth zone of both fingernails and toenails is located in the nail matrix, which is situated beneath the base of the nail and extends under the cuticle (eponychium). It is within the nail matrix that new nail cells are actively dividing and being produced, leading to the elongation of the nail plate. **Typical Rate of Nail Growth:** The rate of nail growth can vary among individuals and is influenced by factors such as age, genetics, overall health, and environmental conditions. However, on average: - Fingernails typically grow at a rate of about 3 millimeters (1/8 inch) per month. This equates to approximately 0.1 millimeters per day. - Toenails tend to grow more slowly than fingernails, with an average rate of about 1 millimeter (1/25 inch) per month. Nail growth is a continuous process, and nails will continue to grow as long as the nail matrix remains healthy and undamaged. Nail growth rates can change during one's lifetime, with some people experiencing faster growth during childhood and adolescence. It's important to note that the appearance and health of nails can also be influenced by diet, hydration, and various medical conditions. Proper nail care, including keeping nails clean, trimming them regularly, and avoiding excessive use of nail products, can help maintain healthy and attractive nails.

Work Step by Step

Fingernails and toenails are composed of layers of a protein called keratin and serve to protect the sensitive tips of our fingers and toes. Here's an overview of their anatomy, the location of their growth zone, and the typical rate of nail growth: **Anatomy of Fingernails and Toenails:** 1. **Nail Plate:** This is the visible, hard part of the nail that extends beyond the fingertip or toe. It is composed of tightly packed layers of dead, flattened, and fully keratinized nail cells. 2. **Nail Bed:** The nail bed is the tissue beneath the nail plate. It is rich in blood vessels and helps nourish the growing nail. 3. **Lunula:** The lunula is the crescent-shaped, whitish area at the base of the nail, visible on some but not all nails. It is the visible part of the nail matrix. 4. **Nail Matrix:** The nail matrix is located beneath the base of the nail and extends under the cuticle (eponychium). It is the tissue responsible for producing new nail cells, and it plays a crucial role in nail growth. 5. **Cuticle (Eponychium):** The cuticle is the thin layer of tissue that covers the base of the nail, protecting the nail matrix from external elements and potential infections. **Location of the Growth Zone:** The growth zone of both fingernails and toenails is located in the nail matrix, which is situated beneath the base of the nail and extends under the cuticle (eponychium). It is within the nail matrix that new nail cells are actively dividing and being produced, leading to the elongation of the nail plate. **Typical Rate of Nail Growth:** The rate of nail growth can vary among individuals and is influenced by factors such as age, genetics, overall health, and environmental conditions. However, on average: - Fingernails typically grow at a rate of about 3 millimeters (1/8 inch) per month. This equates to approximately 0.1 millimeters per day. - Toenails tend to grow more slowly than fingernails, with an average rate of about 1 millimeter (1/25 inch) per month. Nail growth is a continuous process, and nails will continue to grow as long as the nail matrix remains healthy and undamaged. Nail growth rates can change during one's lifetime, with some people experiencing faster growth during childhood and adolescence. It's important to note that the appearance and health of nails can also be influenced by diet, hydration, and various medical conditions. Proper nail care, including keeping nails clean, trimming them regularly, and avoiding excessive use of nail products, can help maintain healthy and attractive nails.
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