Inside the Human Body

Nomad Press

A division of Nomad Communications

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Copyright © 2020 by Nomad Press. All rights reserved.

No part of this book may be reproduced in any form without permission in writing from the publisher, except by a reviewer who may quote brief passages in a review or for limited educational use. The trademark Nomad Press and the Nomad Press logo are trademarks of Nomad Communications, Inc.

ISBN Softcover: 978-1-61930-903-6

ISBN Hardcover: 978-1-61930-900-5

Educational Consultant, Marla Conn

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Contents

Timeline

Introduction

Let’s Talk About the Human Body

Chapter 1

Start With the Cells

Chapter 2

Move It with Muscles and Bones

Chapter 3

Pumping Life: The Cardiovascular System

Chapter 4

Breathe Deep: The Respiratory System

Chapter 5

Command Central: The Nervous System

Chapter 6

Chemical Messages: The Endocrine System

Chapter 7

Break It Down: The Digestive System

Chapter 8

Producing Life: The Reproductive System

Chapter 9

Healthy Bodies

Glossary Metric Conversions Resources Selected Bibliography Index

TIMELINE

Introduction

Let’s Talk About the Human Body

Why is it important to study anatomy?

The more we know about how our bodies work, the better able we are to stay healthy for our entire lives! Plus, the science of anatomy is fascinating.

Your body is an amazing machine! Trillions of unique cells work together to form the tissues, organs, and body systems that allow you to run and jump, laugh and cry, feel pain and joy. Some of the body’s most complex workings hum along without you even realizing all the action that goes on behind the scenes.

For example, when you eat, the body’s digestive system breaks down food to release essential nutrients to fuel the body. The heart and cardiovascular system pump nutrients via blood to every part of the body through a network of blood vessels. At the same time, the body’s immune system stands guard, ready to jump into action to protect the body from disease and infection.

These are just a few of the amazing things the body does to sustain life.

For thousands of years, people have been curious about how the human body works. The ancient Egyptians were interested in the human body and had some knowledge about its structure, even if they didn’t fully understand how it worked. Written around the seventeenth century BCE, the Edwin Smith papyrus is an ancient Egyptian medical text. The papyrus is believed to be the world’s earliest known medical document. It describes different illnesses and how to treat them. But how did the ancient Egyptians learn about the human body without today’s technology?

Historically, scientists who wanted to learn about the human body and its structure had to dissect bodies. Of course, it was possible to do this only after a person had died! Scientists had no way to see the body’s inner workings in action.

Today, different technologies allow scientists to see inside a living body. X-rays, magnetic resonance imaging (MRI), and electron microscopes allow people to study a living human body. Using these technologies, scientists can examine the smallest parts of the body and learn how everything works together.

The Edwin Smith papyrus

Scientists who study the human body believe that every structure and process, no matter how small, is essential to the body’s inner workings. Every structure and process plays its part in keeping the body alive and running like a fine-tuned machine.

The human body is more than a structure. It is a living, working machine.

PRIMARY SOURCES

ANATOMY VS. PHYSIOLOGY

The study of the human body is divided into two main areas—anatomy and physiology.

Anatomy is the study of how the body is structured. The human body is a complicated puzzle with bones, muscles, organs, nerves, and vessels organized in specific patterns. Anatomy can be divided into several sub-specialties.

•Gross anatomy studies the large parts of the body—the structures that the naked eye can see, including bones, muscles, the heart, lungs, and more.

•Histologic anatomy studies the different types of tissue throughout the body and the cells that make up these tissues.

•Developmental anatomy studies the life cycle of the human body and how body parts change during a person’s lifespan.

•Comparative anatomy studies the similarities and differences in the structures of different species. This information can give scientists new insights into the different structures of the human body and how they function.

Physiology is the study of how the body functions. Specifically, it is the study of how cells, tissues, and organisms work. Physiologists try to answer key questions that range from the function of single cells to how the body adapts to changes in temperature and environment.

Physiology also helps scientists better understand human disease and develop new methods for treating those diseases.

IT’S ALL IN THE PERSPECTIVE

As we talk about the body in this book, it’s important to have the right perspective. For example, where is left on the body? A term such as left can