UMich Nurs 210/211: Chapter 26

In adults, body fluids make up between

55% and 65% of total body mass

Bodily fluids are present in two main compartments

Inside cells (2/3) and outside cells (1/3)

Intracellular fluids is

cytosol

Extracellular fluid is

interstitial fluid (80%) and blood plasma (20%)

The plasma membrane of cells separate

Intracellular fluid from interstitial fluid

Blood vessel walls divide the

interstitial fluid from blood plasma

Capillary walls are thin enough to allow

exchange of water and solutes between blood plasma and interstitial fluid

Filtration, reabsorption, diffusion, and osmosis allow

continuous exchange of water and solutes among body fluid compartments

The balance of inorganic compounds that dissociate into ions (electrolytes) is closely related to ?

fluid balance

The body gains water by

ingestion and metabolic synthesis

The body loses water via

urination, perspiration, exhalation, and in feces

Elimination of excess body water occurs through

urine production

The amount of urinary salt loss is the main factor determining

body fluid volume

The two main solutes in urine are

sodium ions (Na+) and chloride ions (Cl-)

Wherever solutes go,

water follows

Three major hormones control homeostasis do Na+ and Cl- and water:

1. Angiotensin II

2. Aldosterone

3. Atrial Natriuretic peptide (ANP)

The major hormone that regulates water loss is

antidiuretic hormone (ADH)

When the extracellular fluid is isotonic to the cells of the body

they do not shrink or swell

Changes in the osmolarity of the extracellular fluids (dehydration/over hydration) can cause

The cells of the body to shrink or swell

Ions form when electrolytes

dissolve and dissociate

Functions of electrolytes are to

1. Control osmosis of water between fluid compartments

2. Help maintain the acid-base balance

3. Carry electrical current

4. Serve as cofactors

The concentration of ions are expressed in

Units of milliequivalents per liter (mEq/liter)

Blood plasma, interstitial fluid, and Intracellular fluid have different

concentrations of electrolytes and protein ions

Blood plasma contains ____ protein ions; interstitial fluid contains ____

Many; only a few

What is the most abundant cation in extracellular fluid?

Sodium

Sodium in extracellular fluid is used for

Impulse transmission, muscle contraction, fluid, and electrolyte balance

The sodium level in extracellular fluid is controlled by

Aldosterone, ADH, and ANP

What is the major extracellular anion in electrolytes in body fluids?

Chloride

Chloride is used to help

Regulate osmotic pressure between compartments

Chloride is used to form

HCL in the stomach

Regulation of Cl- balance is controlled by

aldosterone

What is the most abundant cation in Intracellular fluid?

Potassium

Potassium is involved in

Fluid volume, impulse conduction, muscle contraction, and regulating pH

In potassium, mineralocorticoids regulate

The plasma level

What is the most important plasma ion?

Bicarbonate

Bicarbonate is a major member of the

Plasma acid-base buffer system

Kidneys reabsorb or secrete

Bicarbonate for final acid-base balance

What is the most abundant mineral in the body?

Calcium

Calcium is the structural component of

bones and teeth

Calcium is used for

blood coagulation, neurotransmitter release, muscle tone, excitability of nerves and muscles

Calcium level in plasma is regulated by

Parathyroid hormone

What occurs as calcium phosphate salt?

Phosphate

Phosphate is used in the

Buffer system

Phosphate is regulated by

parathyroid hormone and calcitriol

What is an intracellular cation?

Magnesium

Magnesium activates enzymes involved in

Carbohydrate and protein metabolism

Magnesium is used in

Myocardial function, transmission in the CNS, and operation of the sodium pump

The pH of arterial blood ranges from

7.35-7.45

Mechanisms that maintain the pH range are:

- Buffer systems

- Exhalation of Carbon Dioxide

- Kidney excretion of H+

What is acidosis?

pH below 7.35

What is alkalosis?

pH above 7.45

What is respiratory acidosis?

blood pH drops due to excessive retention of CO2 leading to excess H2CO3

What is respiratory alkalosis?

blood pH rises due to excessive loss of CO2 as in hyperventilation

What is metabolic acidosis?

arterial blood levels of H+ increases, HCO3- falls

What is metabolic alkalosis?

arterial blood levels of H+ falls, HCO3- rises