Extracellular Fluid The Internal Environment

About 60 per cent of the adult human body is fluid, mainly a water solution of ions and other substances. Although most of this fluid is inside the cells and is called intracellular fluid, about one third is in the spaces outside the cells and

is called extracellular fluid. This extracellular fluid is in constant motion throughout the body. It is transported rapidly in the circulating blood and then mixed between the blood and the tissue fluids by diffusion through the capillary walls.

In the extracellular fluid are the ions and nutrients needed by the cells to maintain cell life. Thus, all cells live in essentially the same environment—the extracellular fluid. For this reason, the extracellular fluid is also called the internal environment of the body, or the milieu intérieur, a term introduced more than 100 years ago by the great 19th-century French physiologist Claude Bernard.

Cells are capable of living, growing, and performing their special functions as long as the proper concentrations of oxygen, glucose, different ions, amino acids, fatty substances, and other constituents are available in this internal environment.

Differences Between Extracellular and Intracellular Fluids.

The extracellular fluid contains large amounts of sodium, chloride, and bicarbonate ions plus nutrients for the cells, such as oxygen, glucose, fatty acids, and amino acids. It also contains carbon dioxide that is being transported from the cells to the lungs to be excreted, plus other cellular waste products that are being transported to the kidneys for excretion.

The intracellular fluid differs significantly from the extracellular fluid; specifically, it contains large amounts of potassium, magnesium, and phosphate ions instead of the sodium and chloride ions found in the extracellular fluid. Special mechanisms for transporting ions through the cell membranes maintain the ion concentration differences between the extracellular and intracellular fluids. These transport processes are discussed in Chapter 4.

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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  • Hagos Alem
    Why extracellularfluid is also called internal environment?
    3 years ago
    Why extracellular fluid is called internal environment?
    3 years ago
  • lamberto endrizzi
    Why ecf is called internal environment are tje ions and nutrient live?
    3 years ago
  • guido diggle
    Why is E.C.F termed as the internal environment for physiology?
    3 years ago
  • Mungo Labingi
    Why ECF called internal environment of the body in bengali?
    2 years ago
  • flambard
    How extracellular and intracellular environment of celll is maintained?
    1 year ago
  • Christian
    Why is extracellular fluid referred to as the body's internal environment?
    1 year ago
    What fluid is inside the internal environment?
    12 months ago
  • Ulpu
    Why extra cellular fluid is called internal environment of the body?
    7 months ago
  • Arnor
    Is intercellular fluid an internal environment?
    5 months ago
  • Nahand
    Why the interstitial fluid is called the internal environment'?
    5 months ago
  • Demetria
    Why is extracellular fluid called the internal environment of the body?
    1 month ago

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