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

By Gary F. Merrill | Go to book overview

6
Kidneys and Renal Physiology

Among the many physiological functions of the kidney—including those that are subject to feedback control—one is preeminent and omnipresent from birth to death. This is the need to maintain the homeostasis of body water and body electrolytes. Except for short-lived maladjustments, water and electrolyte balance among intracellular, extracellular, and intravascular spaces must be maintained twenty-four hours a day throughout a lifetime. Challenges to such a balancing act are presented by the daily cycles of hydration and dehydration we all experience. Consider the states of sleep and wakefulness. During the typical six to eight hours of sleep average adults get, we are steadily losing body water. This happens, in part, each time we exhale and lose water vapor to the atmosphere. It also occurs continuously with evaporation of water through the skin. Thus, during our sleep we lose a certain quantity of water but do not replace it. The net result is dehydration.

Normally from the moment we awake until about lunch time, we are consciously or unconsciously rehydrating. This is driven, in part, by eating breakfast, drinking multiple cups of java, and, earlier, by physiological feedback mechanisms promoting thirst: most notably a dry mouth and the afferent sensory signals it generates. During the sleeping hours, we steadily dehydrate and the homeostasis of water and electrolyte balance among the three compartments gets disturbed. Sensory signals from multiple locations throughout the body apprise the kidneys of these changes. The kidneys react via reflex mechanisms by conserving water. Water conservation during sleep takes place primarily at the distal tubules and collecting ducts of the renal nephrons. These tubular structures have specialized cells designed to transport water from the tubular fluid into the blood. In the membranes of such cells are proteins called aquaporins that form water channels. The number of such channels, that is, the production, release, and insertion of aquaporin proteins, is under physiological

-94-

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.
Buy instant access to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

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?

Help
Full screen
/ 222

matching results for page

    Questia reader help

    How to highlight and cite specific passages

    1. Click or tap the first word you want to select.
    2. Click or tap the last word you want to select, and you’ll see everything in between get selected.
    3. You’ll then get a menu of options like creating a highlight or a citation from that passage of text.

    OK, got it!

    Cited passage

    Style
    Citations are available only to our active members.
    Buy instant access 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.

    Buy instant access to save your work.

    Already a member? Log in now.

    Oops!

    An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.