Our Marvelous Bodies: An Introduction to the Physiology of Human Health

By Gary F. Merrill | Go to book overview

2
Understanding the Mammalian
Nervous ystem

What Are Neurons?

Neurons, or brain cells, come in multiple shapes and sizes. Their common purpose is to communicate. Neurons consist of three basic components that enable them to communicate. These include the cell body or soma, an axon or cable that extends to an adjacent neuron or other effector, and dendrites. Dendrites are shaft-like projections that arise from the cell body and make contact with multiple other neurons in the vicinity of the original cell. Physiologically, dendrites receive incoming information. That information is integrated and analyzed in the cell body. A response is then conducted down the axon to another neuron or some other effector such as a skeletal muscle cell. Neurons are the functional units of all the body's nervous systems.

No one knows how many neurons are present in the human body. In late 2006, I heard a mammalian neuroscientist say that in one cubic millimeter of tissue from the rat cerebral cortex, there are more neurons than there are stars in the universe. I don't know how he arrived at this figure. However, as the universe is composed mainly of cold, dark, matter—as much as 70 percent as estimated by some astrophysicists—so is the human nervous system composed of cells and tissues other than neurons. One of the most abundant of these is the glial cell. Glial cells are thought to be supportive to neurons. They influence blood flow, provide structural support, influence remodeling after disease and damage, and are thought to contribute to the neuron's communicative/metabolic functions.

Neurons communicate via two processes. The first is called conduction and the second transmission. I will say more about each later, but for now conduction refers to the physiological processes involved in getting a message from the cell body, down the axon, and to the effector.

Nerve axons can be myelinated or nonmyelinated. Myelin is an insulationlike fatty sheath that encases the axon but is disrupted at regular intervals along

-18-

Notes for this page

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items

Items saved from this book

This book has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this book

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this page

Cited page

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited page

Bookmark this page
Our Marvelous Bodies: An Introduction to the Physiology of Human Health
Table of contents

Table of contents

  • Title Page iii
  • Contents v
  • List of Figures ix
  • List of Tables xi
  • Preface xiii
  • 1: The Foundation 1
  • 2: Understanding the Mammalian Nervous Ystem 18
  • 3: The Endocrine System and Physiological Communication 35
  • 4: The Cardiovascular System and the Blood 53
  • 5: Health and the Respiratory System 76
  • 6: Kidneys and Renal Physiology 94
  • 7: The Gastrointestinal System 109
  • 8: The Reproductive System 128
  • 9: The Immune System 138
  • 10: Muscle Function 151
  • 11: Integrated Physiological Responses 162
  • 12: For the Record 170
  • Glossary 185
  • Notes and Suggested Reading 199
  • Index 209
  • About the Author 221
Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this book

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Full screen
/ 222

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited passage

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.