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A pie graph showing the proportion of total body fluid in each of the body’s fluid compartments

This pie chart shows that about 55% of water in the human body is intracellular fluid. About 30% of the water in the human body is interstitial fluid. Most of the remaining 15% of water is plasma, along with a small percentage labeled “other fluid”.
Most of the water in the body is intracellular fluid. The second largest volume is the interstitial fluid, which surrounds cells that are not blood cells.

Extracellular fluid

The ECF accounts for the other one-third of the body’s water content. Approximately 20 percent of the ECF is found in plasma. Plasma travels through the body in blood vessels and transports a range of materials, including blood cells, proteins (including clotting factors and antibodies), electrolytes, nutrients, gases, and wastes. Gases, nutrients, and waste materials travel between capillaries and cells through the IF. Cells are separated from the IF by a selectively permeable cell membrane that helps regulate the passage of materials between the IF and the interior of the cell.

The body has other water-based ECF. These include the cerebrospinal fluid that bathes the brain and spinal cord, lymph, the synovial fluid in joints, the pleural fluid in the pleural cavities, the pericardial fluid in the cardiac sac, the peritoneal fluid in the peritoneal cavity, and the aqueous humor of the eye. Because these fluids are outside of cells, these fluids are also considered components of the ECF compartment.

Composition of body fluids

The compositions of the two components of the ECF—plasma and IF—are more similar to each other than either is to the ICF ( [link] ). Blood plasma has high concentrations of sodium, chloride, bicarbonate, and protein. The IF has high concentrations of sodium, chloride, and bicarbonate, but a relatively lower concentration of protein. In contrast, the ICF has elevated amounts of potassium, phosphate, magnesium, and protein. Overall, the ICF contains high concentrations of potassium and phosphate ( HPO 4 2 ), whereas both plasma and the ECF contain high concentrations of sodium and chloride.

The concentrations of different elements in key bodily fluids

This bar graph shows the concentration of several ions and proteins in intracellular fluid, interstitial fluid and plasma. The ions and proteins are categories on the X axis . The Y axis shows concentration, in milliequivalents per liter, ranging from zero to 160. Three different colored bars are shown above each compound on the X axis. One bar represents intracellular fluid (ICF), a second bar represents interstitial fluid (IF, which is part of ECF) and the third bar represents plasma (ECF). Intracellular fluid contains high concentrations of K plus and HPO four two minus. It has lower concentrations of MG two plus and protein, and negligible amounts of the other compounds. Interstitial fluid contains high concentrations of NA plus and CL minus, along with a smaller amount of HCO 3 minus, and negligible amounts of the other compounds. Plasma contains large concentrations of NA plus and CL minus, with smaller concentrations of HCO 3 minus and protein, and negligible amounts of the other compounds.
The graph shows the composition of the ICF, IF, and plasma. The compositions of plasma and IF are similar to one another but are quite different from the composition of the ICF.
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Watch this video to learn more about body fluids, fluid compartments, and electrolytes. When blood volume decreases due to sweating, from what source is water taken in by the blood?

Most body fluids are neutral in charge. Thus, cations, or positively charged ions, and anions, or negatively charged ions, are balanced in fluids. As seen in the previous graph, sodium (Na + ) ions and chloride (Cl - ) ions are concentrated in the ECF of the body, whereas potassium (K + ) ions are concentrated inside cells. Although sodium and potassium can “leak” through “pores” into and out of cells, respectively, the high levels of potassium and low levels of sodium in the ICF are maintained by sodium-potassium pumps in the cell membranes. These pumps use the energy supplied by ATP to pump sodium out of the cell and potassium into the cell ( [link] ).

Questions & Answers

what is the consequence of performing CPR on a functioning heart.
Pyefa Reply
The central part of the body
Alex Reply
i thought a cell is the fuctional unit of an orgarnism.
mutesi Reply
what is the name for inflammation of middle ear?
Madu
otitis media
Chidiebere
Explain the major features and properties of the cell membrane
Robina Reply
contants ofa lipid bilayers w the enbedded proteins it is faction of the cell membaren
bariise
it is made up of protein,fat and a small portion of carbohydrates. it is semipermeable but impermeable to uncharged water molecules.
Chidiebere
Describe an experiment to verify the law of constant composition
Ssekamatte
thanks
Momoh
amazing the exprement is hard to set up can you please help us describe it for us?
Momoh
thx
Robina
hi guys
unimarwat
blowing your colon straight outa ya ass because you ate 4lbs of uncooked fish the night prior
Noah
What are blood vessels of will's circle
Madu Reply
vertebral arteries and cerebral arteries
Chidiebere
What are sutures of cranial cavity ?
Madu Reply
there are four. the coronal, sagittal, squamous and lambhoidal sutured
Chidiebere
structure of a cell
Robina
pelvic cavity contents?
unimarwat Reply
ilium ,ischium ,pubis
Madu
but that is the three parts of the hip bone
Chidiebere
Describe the muscular skeletal system in terms of definition.. Skeleton Apendicular skeleton Axial skeleton Joints
Sherrine Reply
the basic framework of body made and cartilage is called skeleton skeleton which form limbs is called appendicular skeleton skeleton which form main axis of body is called axial skeleton the points at two or more bones meets is called joints
unimarwat
write short notes on ligaments,curves and moverment of vertebral column.
mutesi Reply
cranial nerves notes
unimarwat
what is the Analysis
ROHIT Reply
what is Anatomy
ROHIT Reply
it's a organs and bouns reading
AJITH
Cutting Up
Nonie
Cutting Up
Nonie
to dissect
Nonie
what usually cause blood pressurae
Abdullateef Reply
too much salt in the diet
Abuusu
older age
Abuusu
Even family history of high blood pressure
Abuusu
yes
Yaqub
too much salt in the diet
Yaqub
stress is the leading factor
Richard
smoking and too much alcohol consumption
Annu
obesity can also cause hypertension
Yaqub
high temperature of the body high salt of the body
Drs
how does the temperature affect the blood pressure?
Chidiebere
sex
Onavwie
What sex.?
Arshad
Male
Vikas
i mearnt gender,there's increased blood pressure in male than female
Onavwie
guys, read the question, involuntary pumping of heart causes the blood pressure in the arteries, he has not asked about high or low BP.
Jess
explain the cellular mechanism that produces tetanus and summation
Jenica Reply
epithelial cells polerity
jitendra Reply
tissues
Deepak
demonstrate the fluid replacement in the body
John Reply
the red blood cells is in the long bones or flat bones?
isbii

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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