Body Fluids

Question 1

What is body fluid volume?

Answer 1

total body water = intracellular fluid volume + extracellular fluid volume

Question 2

What is extracellular fluid volume equal to?

Answer 2

interstitial fluid volume + plasma volume + lymph volume + transcellular fluid volume

Question 3

What is the distribution of body fluid between extracellular and intracellular?

Answer 3

extracellular = 1/3
intracellular = 2/3

Question 4

What is the approximate normal distribution of extracellular body fluid?

Answer 4

interstitial = 3/4 of ECF = 1/4 of total body fluid
plasma = 1/4 of ECF = 1/12 of total body fluid
lymph & transcellular fluid = very small volume, negligent

Question 5

How is the concentration of Na+ in plasma different from concentration of Na+ in interstitial fluid?

Answer 5

plasma [Na+] = interstitial fluid [Na+]

Question 6

Interstitial [K+] vs. skeletal muscle intracellular fluid [K+]?

Answer 6

Interstitial [K+] < skeletal muscle intracellular fluid [K+]

Question 7

plasma [Ca2+] vs. skeletal muscle cytosol [Ca2+]?

Answer 7

plasma [Ca2+] > skeletal muscle cytosol [Ca2+]

Question 8

plasma [plasma proteins] vs. interstitial fluid [plasma proteins]?

Answer 8

plasma [plasma proteins] > interstitial fluid [plasma proteins]

Question 9

contribution of normal [plasma glucose] to plasma osmolarity vs. contribution of normal [plasma sodium] to total plasma osmolarity?

Answer 9

contribution of normal [plasma glucose] to plasma osmolarity < contribution of normal [plasma sodium] to total plasma osmolarity

Question 10

total osmolarity of plasma vs. total osmolarity of the intracellular fluid in red blood cells?

Answer 10

total osmolarity of plasma = total osmolarity of the intracellular fluid in red blood cells

Question 11

interstitial fluid volume vs. plasma volume?

Answer 11

interstitial fluid volume > plasma volume

Question 12

interstitial fluid volume vs. intracellular fluid volume?

Answer 12

interstitial fluid volume < intracellular fluid volume

Question 13

sum of interstitial fluid plus blood volume plus lymph volume vs. extracellular fluid volume?

Answer 13

sum of interstitial fluid plus blood volume plus lymph volume > extracellular fluid volume

Question 14

calculated plasma volume when some of the indicator dye used to measure it is unknowingly injected subcutaneously (into interstitial space) instead of IV vs. calculated plasma volume when all of the indicator dye is injected IV?

Answer 14

calculated plasma volume when some of the indicator dye used to measure it is unknowingly injected subcutaneously (into interstitial space) instead of IV > calculated plasma volume when all of the indicator dye is injected IV

Question 15

What are osmotic forces?

Answer 15

determine the distribution of water between extracellular and intracellular fluid
if total extracellular osmolarity > total intracellular osmolarity, water moves out of cells
if total intracellular osmolarity > total extracellular osmolarity, water moves into cells

Question 16

What is dehydration?

Answer 16

state of less than normal extracellular fluid volume
intracellular fluid volume can be normal, increased, or decreased
body fluid may be isosmotic, hyper osmotic, or hyposmotic

Question 17

What is over hydration?

Answer 17

state of more than normal extracellular fluid volume

Question 18

What is isosmotic dehydration?

Answer 18

e.g. hemorrhage
the lost extracellular fluid has the same osmolarity as normal body fluid, so the fluid loss does not change extracellular fluid osmolarity

Question 19

What is isosmotic over hydration?

Answer 19

e.g. IV infusion of large amount of isotonic NaCl solution
the fluid that is added to the extracellular space has the same osmolarity as the existing body fluid, so the addition of the extra fluid does not change the extracellular fluid osmolarity

Question 20

What is hypo osmotic over hydration?

Answer 20

e.g. drinking very large amounts of water
the fluid that is added to the extracellular space has a lower osmolarity than the existing body fluid, so the addition of the extra fluid makes the extracellular fluid hypoosmotic

Question 21

What is hyper osmotic dehydration?

Answer 21

e.g. large sweat loss without water replacement
sweat is more dilute (has lower osmolarity) than normal body fluid, so sweat loss without water replacement leads to a concentration (hyperosmolarity) of the remaining extracellular fluid

Question 22

What is hyper osmotic over hydration?

Answer 22

e.g. infusion of large volume of hypertonic saline solution
the fluid that is added to the extracellular space has a higher osmolarity than the existing body fluid, so the addition of the extra fluid makes the extracellular fluid hyperosmotic

Question 23

What is hypo osmotic dehydration?

Answer 23

e.g. profuse sweating, followed by drinking water
although sweat is more dilute (has a lower osmolarity) than normal body fluid, a large sweat loss does remove solute from the body; if the volume of sweat loss is replaced with just water, the extracellular fluid becomes diluted (hypo osmotic)