Introduction

Congratulations on your decision to study human anatomy and physiology. The knowledge you gain from your study is of value in many aspects of your life.

A little background in anatomy and physiology should be considered a valuable part of anyone’s education. Health and medical matters are part of world events and people’s daily lives. Basic knowledge of anatomy and physiology gets you started when trying to make sense of the news about epidemics, novel drugs and medical devices, and purported environmental hazards, to name just a few examples. Everyone has a problem with some aspect of his or her anatomy and physiology at some point, and this knowledge can help you be a better parent, spouse, caregiver, neighbor, friend, or colleague.

Knowledge of anatomy and physiology may also benefit your own health. Sometimes, comprehension of a particular fact or concept can help drive a good decision about long-term health matters, such as the demonstrated benefits of exercise, or it may help you take appropriate action in the context of a specific medical problem, such as an infection, a cut, or a muscle strain. You may understand your doctors’ instructions better during a course of treatment, which may give you a better medical outcome.

About This Book

Anatomy Essentials For Dummies guides you on a quick walk-through of human anatomy and physiology. It doesn’t have the same degree of technical detail as a textbook. It contains relatively little in the way of lists of important anatomical structures, for instance. We expect that most readers are using this book as a complementary resource for course work in anatomy and physiology at the high-school or college level. Therefore, the goals of this book are to be informal but not unscientific, brief but not sketchy, and information-rich but accessible to readers at many levels.

Conventions Used in This Book

We use the following conventions throughout the text to make the presentation of information consistent and easy to understand:

New terms appear in italic and are closely followed by an easy-to-understand definition.

Bold is used to highlight keywords in bulleted lists.

If you’re using this book as a supplement to an assigned textbook, note that your course materials may name structures and physiological substances using a different nomenclature (naming system) than the one we use in this book.

Foolish Assumptions

We’re guessing that you fall into one of these categories:

Formal student: You’re a high-school or college student enrolled in a basic anatomy and physiology course for credit. You need to pass an exam or otherwise demonstrate understanding and retention of data, terminology, and concepts in human anatomy and physiology.

Informal student: You’re not enrolled in a credit course, but gaining some background in human anatomy and physiology is important to you for personal or professional reasons.

Casual reader: Here you are with a book on your hands and a little time to spend reading it. And it’s all about you!

Icons Used in This Book

The little round pictures that you see in the margins throughout this book are icons that alert you to different kinds of valuable information.

Remember This icon serves to highlight information we think you should permanently store in your mental anatomy and physiology file.

Tip The bull’s-eye symbol lets you know what you can do to improve your understanding of an anatomical structure.

Where to Go from Here

If you’re currently enrolled in (or planning to enroll in) a formal course in human anatomy and physiology, you may get the most benefit by becoming familiar with this book a week or two before your course begins. Peruse the book as you would any science book: Look at the table of contents and the index, read the Introduction, and then start reading the chapters. Look at the figures as you read. You’ll probably be able to get through the entire book in just a couple of sittings. Then go back and reread chapters you found particularly interesting, relevant, or puzzling. Study the illustrations carefully. Pay attention to technical terminology; your instructors will use it and expect you to use it, too.

If you’re a casual reader (you’re not enrolled in a formal course in anatomy and physiology and have little or no background in biology), why not head to the chapters that sound the most interesting to you? Don’t sweat too much over terminology; for your purposes, saying of my lungs communicates as well as pulmonary. (If you also enjoy word games, though, you can get started on a whole new vocabulary.) Keep the book handy for future reference the next time you wonder what the heck they’re talking about in a TV drug ad.

Chapter 1

Focusing on the Framework of Anatomy and Physiology

IN THIS CHAPTER

Bullet Connecting anatomy and physiology and science

Bullet Making out anatomy jargon

Bullet Sorting organisms by life’s levels of organization

Bullet Discovering how metabolism works

Bullet Using homeostasis to maintain balance

Human anatomy is the science of the human body’s structures — things that can be touched, weighed, or analyzed. Human physiology is the chemistry and physics of these structures, including how they all work together to support the processes of life in each individual.

If you put these two subjects together, you have the means of understanding your body on a whole new level. This chapter sets up your study of anatomy and physiology by shining a light on the very framework of the subjects, from key terminology and the levels of organization within an organism to descriptions of metabolism and homeostasis.

Looking at the Science of Anatomy and Physiology

Human anatomy and physiology are closely related to biology, which is the science of living beings and their relationships with the rest of the universe, including all other living beings. If you’ve studied biology, you understand the basics of how organisms operate. Anatomy and physiology narrow the science of biology by looking at the specifics of one species: Homo sapiens.

Remember Anatomy is structure; physiology is function. You can’t talk about one without talking about the other.

Fitting anatomy and physiology into science

Biologists take for granted that human anatomy and physiology evolved from the anatomy and physiology of ancient forms. These scientists base their work on the assumption that every structure and process, no matter how tiny in scope, must somehow contribute to the survival of the individual. So each process — and the structures within which the chemistry and physics of the process actually happen — must help keep the individual alive and meeting the relentless challenges of a continually changing environment. Evolution favors processes that work.

Human pathophysiology is the science of human anatomy and physiology gone wrong. (The prefix path- is Greek for suffering.) It’s the interface of human biology and medical science. Clinical medicine is the application of medical science to alleviate an anatomical or physiological problem in an individual human.

Breaking down the subsets of anatomy

The science of anatomy features the following major subsets (throughout this book, you encounter some information from each one):

Gross anatomy: The study of the large parts of any animal body that can be seen with the unaided eye. (We concentrate on this aspect of anatomy in this book.)

Histologic anatomy: The study of different tissue types and the cells that comprise them. Histologic anatomists use a variety of microscopes to study these cells and tissues that make up the body.

Developmental anatomy: The study of the life cycle of the individual, from fertilized egg through adulthood, senescence (aging), and death. Body parts change throughout the life span.

Comparative anatomy: The study of the similarities and differences among the anatomical structures of different species, including extinct species. This subject is closely related to evolutionary biology. Information from comparative anatomy helps scientists understand the human body’s structures and processes. For example, the comparative anatomy of humans and living and extinct apes elucidates the structures in the human limbs that enable the bipedal posture.

Familiarizing Yourself with Anatomical Jargon

Jargon is a set of words and phrases that people who know a lot about a particular subject use to talk together. You can find jargon in every field (scientific or not), every workplace, every town, and every home. Families and close friends almost always use jargon in conversations with one another. Plumbers use jargon to communicate about plumbing. Anatomists and physiologists use jargon and technical terminology, much of which is shared with medicine and other fields of biology, especially human biology.

Scientists try to create terminology that’s precise and easy to understand by developing it systematically. That is, they create new words by putting together existing and known elements. They use certain syllables or word fragments over and over to build new terms.

Remember With a little help from this book, you can start recognizing some of these fragments. Then you can put the meanings of different fragments together and accurately guess the meaning of a term you’ve never seen before, just as you can understand a sentence you’ve never read before. Table 1-1 gets you started by listing some word fragments related to the organ systems we cover in this book.

TABLE 1-1 Technical Anatomical Word Fragments

You may be asking why you should always have to parse and put back together terms like iliohypogastric. A key reason is the contrast between the preciseness with which scientists must name and describe the things they talk about in a scientific context and the relative vagueness and changeability of terms in plain English. Terms that people use in common speech are understood slightly differently by different people, and the meanings are always undergoing change.

Not so long ago, for example, no one speaking plain English used the term laptop to refer to a computer or hybrid to talk about a car. It’s possible that, not many years from now, almost no one will understand what people meant by those words. In contrast, scientific Greek and Latin stopped changing centuries ago: ilio, hypo, and gastro have the same meanings now as they did 200 years ago.

Problems can come up when the specialists who use the jargon want to communicate with someone outside their field. The specialists must translate their message into more common terms to communicate it. Problems can also come up when someone approaching a field, such as a student, fails to make progress understanding and speaking the field’s jargon. This book aims to help you make the necessary progress.

Tip Every time you come across an anatomical or physiological term that’s new to you, pull it apart to see whether any of its fragments are familiar. Using this knowledge, go as far as you can in guessing the meaning of the whole term. After studying Table 1-1, you should be able to make some pretty good guesses.

Arranging Organisms by Levels of Organization

Anatomy and physiology focus on the different levels of the organism, or the individual body. The life processes of the organism are built and maintained at the following several physical levels, known as levels of organization:

The cellular level

The tissue level

The organ level

The organ system level

The organism level

You can see all these levels in Figure 1-1. In this section, we review these levels, starting with the smallest.

FIGURE 1-1: Levels of organization in the human body.

Level I: The cellular level

If you examine a sample of any human tissue under a microscope, you see cells, possibly millions of cells. All living things are made of cells. In fact, having a cellular level of organization is inherent in any definition of organism. We discuss the cellular level of organization in some detail in Chapter 2.

Level II: The tissue level

A tissue is a structure made of many cells — usually several different kinds of cells — that performs a specific function. Tissues are divided into four classes:

Connective tissue serves to support body parts and bind them together.

Epithelial tissue (epithelium) lines the inside of organs within the body and covers the body. The outer layer of the skin is made up of epithelial tissue.

Muscle tissue is found in the muscles, which allow your body parts to move; in the walls of hollow organs to help move their contents along; and in the heart to move blood along via the acts of contraction and relaxation. (Find out more about muscles in Chapter 3.)

Nervous tissue transmits impulses and forms nerves. Brain tissue is nervous tissue. (We talk about the nervous system in Chapter 9.)

Level III: The organ level

An organ is a part of the body that performs a specialized physiological function. For example, the stomach is an organ that has the specific physiological job of breaking down food. By definition, an organ is made up of at least two different tissue types; many organs contain tissues of all four types. Although we can name and describe all four tissue types that make up all organs, as we do in the preceding section, listing all the organs in the body wouldn’t be so easy.

Remember The organs that belong to one system can have functions integral to another system. In fact, most organs contribute to more than one system. The blood vessels are an excellent example: They serve as a transportation network, delivering nutrients produced by the digestive system to the skeletal muscles to provide energy for locomotion and to a woman’s uterus to support her developing fetus. These vessels also remove the byproducts of the energy consumed in locomotion and by the fetus in development and carry them to the organs of the urinary system for excretion.

Level IV: The organ system level

Human anatomists and physiologists have divided the human body into organ systems, groups of organs that work together to meet a major physiological need. For example,