Chapter 43: Fluid and Electrolyte Balance

What tissue contains he least amount of water?

adipose tissue

What makes up Extracellular Fluid?

Plasma, interstitial fluid, transcellular fluid

What are example of transcellular fluid?

Cerebrospinal fluid, joint fluids, humors of eye

What is intracellular Fluid?

water within the cell

Volume of intracellular fluid

25 L

volume of interstitial fluid

12 L

Volume of plasma

3 L

Glomerular filtration rate

rate of movement of fluid out of the glomerulus into Bowman space

Fluid balance

when required amounts of H2O and solutes are proportioned correctly

Water % body mass in infants


Water % body mass in men


Water % body mass in woment



molecules that dissociate into ions when dissolved in H2O

Compartments where fluids are present & amt

2/3 intracellular fluid, cytosol
1//3 extracellular fluid

what makes up extracellular fluid?

80:20 interstitial: plasma

What separates intracellular fluid and interstitial fluid?

Plasma Membrane

What separates interstitial fluid from blood plasma?

Blood Vessels

What processes allow continuous exchange of H2O and solutes?

filtration, reabsorption, diffusion, osmosis

Cardinal rule of Fluid Balance

fluid balance is only maintained if input=output

Average intake of H2O

2500 mL/day

How do we gain H2O?

ingestion and metabolism

How does water loss occur

Kidneys excrete
Skin Evaporates
Lungs exhale
GI tract excrete

Amt H2O kidneys excrete

1500 ml

Amt H2O skin evaporates

600 l

Amt H2O lungs exhale

300 ml

Amt H2O GI tract excretes

100 ml

Where is thirst center?


symptoms of dehydration

decreased flow of saliva, increased blood osmolarity, decreased blood volume

What is the main factor determining body fluid volume?

extent of NaCl loss

hormones regulating body water

ADH, Aldosterone, ANP

ADH role in H2O reg

promotes H2O reabsorption when dehydrated

Aldosterone role in H2O reg

promotes salt reabsorption when dehydrated

ANP role in H2O reg

promotes secretion (and excretion) of salt when over-hydrated


state of dehydration secondary to abnormally excessive water loss


expansion of fluid volume in body

functions of elecrtolytes in body fluids

control osmosis of H2O, maintain acid-base balance, carry electrical current

what is the most abundant cation in extracellular fluid?



condition of decreased sodium concentration in body


condition of increased sodium concentration in body

most abundant anion in extracellular fluid



condition of decreased chloride concentration


condition of increased chloride concentration in body

most abundant cation in intracellular fluid



condition of decreased potassium in body


condition of increased potassium in body

Role of Ca

blood clotting, NT release, maintenance of muscle tone


condition of decreased Ca in body


condition of increased Ca concentration in body