Copyright © 2010, Grant Iannelli, DC Unit 8 Seminar: Fluid/Electrolyte Balance Acid/Base Balance

Copyright © 2010, Grant Iannelli, DC

Unit 8 Seminar: Fluid/Electrolyte

Balance Acid/Base Balance



Fluid balance: homeostasis-constancy of blood fluid levels needed for healthy survival

The total volume and distribution of water must remain normal and relatively constant

Fluid imbalance: the total volume of water in the body or the amounts in one or more of the fluid compartments have increased or decreased beyond normal limits.

Electrolytes-substances such as salts that dissolve or break apart in water solution.


Water is most abundant compound found in the body

60% WEIGHT OF MALE 50% WEIGHT OF FEMALE Fat tissue contains the least

amount of water of any body tissue.

The more fat you have, the less total water content found in your body.

Factors that influence fluid levels:

1. Fat content

2. Total body weight

3. Gender

4. Age


Extracellular fluid-consists mainly of the liquid part of blood (plasma) and the interstitial fluid that surrounds the cells.

Intracellular fluid-located inside the cell

Where is the larger volume found? EF or IF


Three sources of fluid intake:1. The liquids we drink2. The water in the foods we eat3. The water formed by

catabolism of foods

Fluid output from the body occurs through four organs: kidneys, lungs, skin and intestines.

The body maintains fluid balance by excreting urine to match the fluid intake.

What is the most important factor in determining urine volume (pg 463)


Urine volume is regulated by hormones secreted in the pituitary gland and adrenal cortex.

ADH and aldosterone

The rate of water and salt resorption by the renal tubules is the most important factor in determining urine volume.



Water is continually lost from the body through expired air and diffusion through the skin.

What are some symptoms or signs of dehydration? Pg 463


Why is the body unable to reduce its fluid output to zero no matter how dehydrated it is?


Electrolytes-compounds that break up or dissociate in water solution into separate particles

Example: Ordinary table salt (NaCL) can break up into Na and Cl

They are able to conduct electrical current.

Nonelectrolytes-compounds that do not break up or dissociate in water solution.


Ion-a dissociated particle of an electron.

Cation-a positively charted ion

Anion-a negatively charged ion

Cations: sodium, calcium, potassium, magnesium

Ions: chloride, bicarbonate, phosphate and many proteins

Most common cation in EF?

Most common cation in IF?

Most common anion in EF?

Most common anion in IF?


Required for things such as nerve conduction, acid base balance, bone formation, blood clotting, hydrochloric acid production in the stomach.

WHERE SODIUM GOES, WATER SOON FOLLOWS!

If you give normal saline solution, the sodium will go into the blood and then cause fluid to move from the interstitual fluid and into the plasma. This will increase blood volume and stabilize blood pressure.

Edema-tissue swelling-caused by the presence of high amounts of sodium and fluid in the IF.

What is pitting edema?



Capillary blood pressure-pushes water out of the blood in the capillaries and into the IF.

Higher capillary blood pressure equals more fluid being pushed out of the blood and into the IF.

Fluid shift-a decrease in blood volume and an increase in IF volume.

Constant movement of water from the capillaries into the IF and vice versa.

The amount that moves out of the capillary blood depends on the blood pressure.

The amount that moves from the IF into the capillary blood depends on the concentration of blood proteins found in the plasma.


Plasma proteins act as water pulling or water holding.

They hold water in the blood and also pull water into the blood from the IF.

A deficiency in blood proteins can cause less water to move from the IF and into the blood.

This causes blood volumes to decrease and IF volumes to increase.


Where sodium goes, water soon follows The kidneys are the chief regulator of

sodium levels in the body. Aldosterone controls sodium

reabsorption in the kidney. Renal tubule regulation of salt and

water is the most important factor in determining urine volume.


What is dehydration? Total volume of bod fluids is less than normal. IF decreases first, then plasma volume decreases

What is overhydration? Total volume of body fluids greater than normal



Acid-Base Balance


Keeping the concentration of hydrogen ions in the body fluids relatively constant.

Maintaining this balance involves mechanisms in the blood, lungs, kidneys and other body fluids.

Hydrogen ions and hydroxide ions-found in water and all water solutions


A pH of 7.0 is Neutral A pH lower than 7 indicates an

acid solution_this means it has more hydrogen ion concentration and is more acidic.

A pH of more than 7.0 is alkaline-the more alkaline the solution, the higher its pH.

Gastric juice is the most acidic substance in the body.

The term pH indicates a solutions hydrogen ion concentration

Which is more alkaline-venous blood or arterial blood?


CO2 is formed during cellular breakdown of the nutrient glucose. This is known as aerobic respiration.

When the CO2 enters the blood, some combines with H2O and is converted to carbonic acid. H2CO3

The lungs remove this carbonic acid when CO2 is breathed out.


1) the buffer mechanism 2) the respiratory mechanism 3) the urinary mechanism

Blood-7.35-7.45 pH

All of these mechanisms work together to keep blood slighly alkaline.


Chemical substances that prevent a sharp change in the pH of a fluid when an acid or base is added to it.

More acids than bases are usually added to body fluids.

Catabolism produces acids. Some hydrogen ions are absorbed through the GI tract.

Buffer pairs-two kinds of substances Sodium bicarbonate and carbonic acid

are buffer pairs





Explain the respiratory mechanism of pH control.


Respirations play a crucial role in regulating H+ concentrations and controlling body ph.

CO2 diffuses out of venous blood as it moves into the lung capillaries.

The arterial blood leaving the lung capillaries has less CO2 available.

This means less CO2 is available to combine with water to form carbonic acid (remember page 477)

Arterial blood contains less carbonic acid and has a higher pH (more alkaline) than venous blood.


Anything that causes a marked decrease in respirations will in time produce acidosis.

Anything that causes an excessive increase in respirations will in time produce alkalosis

If you hold your breath, no CO2 leaves and the blood content of CO2 rises. This causes an increase in carbonic acid-which results in acidosis.

If you breath rapidly, the levels of CO2 leaving the body increase, which result in less carbonic acid production-which results in alkalosis.


More acids than bases enter the blood, therefore more acids than bases are excreted by the kidneys.

The distal tubules rid the blood of excess acid and also help conserve base at the same time.

See page 481 for more info.


Metabolic acidosis-bicarbonate deficit Metabolic alkalosis-bicarbonate excess Respiratory acidosis-carbonic acid

excess Respiratory alkalosis-carbonic acid

deficit

Which is more common, acidosis or alkalosis? Why?


Metabolic alkalosis is a complication of vomiting.

There is a bicarbonate excess because of the massive loss of chloride from the stomach as hydrochloric acid.

There is excess bicarbonate in the extracellular fluid-uncompensated metabolic alkalosis.

First the body slows down respiration to retain more CO2 which helps increase carbonic acid levels

Second it increases the elimination of bicarbonate in the urine.

Chloride administration may also be given


Respiratory acidosis-carbonic acid excess caused by the retention of CO2 in the body. This occurs when respiration ceases and blood flow through the lung capillaries stops.

After breathing is restored, the body attempts to “blow off” some additional CO2.

See page 485.


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Copyright © 2010, Grant Iannelli, DC Unit 8 Seminar: Fluid/Electrolyte Balance Acid/Base Balance