1. Pima Medical Institute BIO 120
Hole’s Essentials of Human Anatomy & Physiology
Lesson18
Water, Electrolyte, and
Acid-Base Balance
BIO 120 Lesson 18 – Water, Electrolyte, and Acid-Base Balance
David Shier, Jackie Butler, Ricki Lewis, Hole’s Essentials of Human Anatomy & Physiology, 10th Ed. CopyrightThe McGraw-Hill Companies, Inc. Created by Dr. Melissa Eisenhauer, Trevecca Nazarene University

2. Water, Electrolyte, and Acid-Base Balance
 Introduction
A. To be in balance, the quantities of fluids and electrolytes (molecules that release ions in water) leaving the body should be equal to the amounts taken in.
B. Anything that alters the concentrations of electrolytes will also alter the concentration of water, and vice versa.
Two types of substances that are important in maintaining homeostasis in the body are water and electrolytes, which are molecules that release ions in water. To maintain homeostasis, the quantities of water and electrolytes must be in balance; that is, the amounts entering the body must equal the amounts leaving it. Thus, the body requires mechanisms to (1) replace lost water and electrolytes, and (2) excrete any excess.
Because electrolytes are dissolved in the water of body fluids, water balance and electrolyte balance are interdependent. Consequently, anything that alters electrolyte concentrations necessarily alters the water concentration by either adding or removing solutes. Likewise, anything that changes the water concentration changes electrolyte concentrations by either concentrating or diluting them.

3.  Distribution of Body Fluids
A. Fluids occur in compartments in the body, and movement of water and electrolytes between compartments is regulated.
B. Fluid Compartments
1. The average adult female is 52% water by weight, while a male is 63% water, the difference due to the female’s additional adipose tissue.
Body fluids are not uniformly distributed throughout tissues but are in regions, or compartments, of different volumes that contain fluids of varying compositions. The movement of water and electrolytes between these compartments is regulated to stabilize both their distribution and the composition of body fluids.
The body of an average adult female is about 52% water by weight, and that of an average male is about 63% water. These proportions differ because females generally have more adipose tissue, which has little water, than do males. Water in the body (about 40 liters), together with its dissolved electrolytes, is distributed into two major compartments—an intracellular fluid compartment and an extracellular fluid compartment.

4. 2. The intracellular fluid compartment
2. The intracellular fluid compartment includes all the water and electrolytes within cells.
3. The extracellular fluid compartment includes all water and electrolytes outside of cells (interstitial fluid, plasma, and lymph).
4. Transcellular fluid includes the cerebrospinal fluid of the central nervous system, fluids within the eyeball, synovial fluid of the joints, serous fluid within body cavities, and exocrine gland secretions.
The intracellular fluid compartment includes all the water and electrolytes that cell membranes enclose. In other words, intracellular fluid is fluid within cells, and in an adult, it represents about 63% by volume of total body water.
The extracellular fluid compartment includes all the fluid outside cells—within the tissue spaces (interstitial fluid), blood vessels (plasma), and lymphatic vessels (lymph).
Epithelial layers separate a specialized fraction of extracellular fluid from other extracellular fluids. This transcellular fluid includes cerebrospinal fluid of the central nervous system, aqueous and vitreous humors of the eyes, synovial fluid of the joints, serous fluid in body cavities, and extracellular compartment constitute about 37% by volume of total body water (see figure 18.1, slide 5).

5. Cell membranes separate fluids in the intracellular compartment from fluid in the extracellular compartment. Approximately two-thirds of the water in the body is inside cells.
Figure 18.1

6. C. Body Fluid Composition
1. Extracellular fluids have high concentrations of sodium, chloride, and bicarbonate ions, and lesser amounts of potassium, calcium, magnesium, phosphate, and sulfate ions.
2. Intracellular fluid has high concentrations of potassium, phosphate, and magnesium ions, and lesser amounts of sodium, chloride, and bicarbonate ions.
Most extracellular fluids are chemically similar with high concentrations of sodium, chloride, and bicarbonate ions. These fluids include a greater concentration of calcium ions and lesser concentrations of potassium, magnesium, phosphate, and sulfate ions than does intracellular fluid. The blood plasma fraction of extracellular fluid has considerably more protein than does either interstitial fluid or lymph.
Intercellular fluid has high concentrations of potassium, magnesium, and phosphate ions. It includes a greater concentration of sulfate ions and lesser concentrations of sodium, chloride, and bicarbonate ions that do extracellular fluids. Intracellular fluid also has a greater protein concentration that does plasma (see figure 18.2, slide 7).

7. Extracellular fluids have relatively high concentrations of sodium (Na+), calcium (Ca++), chloride (Cl-), and bicarbonate (HCO3-) ions.
Intracellular fluid has relatively high concentrations of potassium (K+), magnesium (Mg++), phosphate (PO4-3), and sulfate SO4-2) ions.
Figure 18.2

8. D. Movement of Fluid between Compartments
1. Hydrostatic pressure and osmotic pressure regulate the movement of water and electrolytes from one compartment to another.
2. Although the composition of body fluids varies from one compartment to another, the total solute concentrations and water amounts are normally equal.
3. A net gain or loss of water will cause shifts affecting both the intracellular and extracellular fluids due to osmosis.
Two major factors regulate the movement of water and electrolytes from one fluid compartment to another: hydrostatic pressure and osmotic pressure (see figure 18.3, slide 10). Fluid leaves the plasma at the arteriolar ends of capillaries and enters the interstitial spaces because of the net outward force of hydrostatic pressure (blood pressure) (see chapter 13, pp ). Fluid returns to the plasma from the interstitial spaces at the venular ends of capillaries because of the net inward force of colloid osmotic pressure due to the plasma proteins. Likewise, the hydrostatic pressure that develops within interstitial spaces forces the fluid therein into lymph capillaries (see chapter 14, p. 379). Lymph circulation returns interstitial fluid to the plasma.
Pressures similarly control fluid movement between the intracellular and extracellular compartments. Because hydrostatic pressure within the cells and surrounding interstitial fluid is ordinarily equal and stable, a change in osmotic pressure is the likely cause of any net fluid movement.
The sodium ion concentration in extracellular fluid is especially high. A decrease in their concentration causes net movement of water for the extracellular compartment into the intracellular compartment by osmosis. As a consequence, the cells swell. Conversely, if the sodium ion concentration in interstitial fluid increase, the net movement of water is outward from the intracellular compartment, and cells shrink as they lose water.

9. Net movements of fluids between compartments result from difference in hydrostatic and osmotic pressures.
Figure 18.3

10. Water Balance
A. Water balance exists when water intake equals water output.
B. Water Intake
1. The volume of water gained each day varies from one individual to the next.
2. About 60% of daily water is gained from drinking, another 30% comes from moist foods, and 10% from the water of metabolism.
Water balance exists when total water intake equals total water output. Homeostatic mechanisms maintain water balance.
The volume of water gained each day varies from individual to individual. An average adult living in a moderate environment takes in about 2,500 milliliters. Of this volume, drinking water or beverages supply about 60%, while moist foods provide another 30%. The remaining 10% is a by-product of the oxidative metabolism (see chapter 4, p. 80) of nutrients and is called water of metabolism (see figure 18.4, slide 17).

11. C. Regulation of Water Intake
1. The thirst mechanism is the primary regulator of water intake.
2. The thirst mechanism derives from the osmotic pressure of extracellular fluids and a thirst center in the hypothalamus.
3. Once water is taken in, the resulting distention of the stomach will inhibit the thirst mechanism.
The primary regulator of water intake is thirst. The intense feeling of thirst derives form the effect of osmotic pressure of extracellular fluids on a thirst center in the hypothalamus. As the body loses water, the osmotic pressure of extracellular fluids increases. This stimulates osmoreceptors in the thirst center, which cause the person to feel thirsty and to seek water.
Thirst is a homeostatic mechanism, normally triggered whenever total body water decreases by as little as 1%. Drinking distends the stomach wall, triggering nerve impulses that inhibit the thirst mechanism. In this way, drinking stops even before the swallowed water is absorbed, preventing the person from drinking too much.

12. D. Water Output
1. Water is lost in urine, feces, perspiration, evaporation from skin (insensible perspiration), and from the lungs during breathing.
2. The route of water loss depends on temperature, relative humidity, and physical exercise.
Water normally enters the body only through the mouth, but it can be lost by a variety of routes. These include obvious losses in urine, feces, and sweat (sensible perspiration), as well as less obvious losses, such as evaporation of water from the skin (insensible perspiration) and from the lungs during breathing. Water loss from these routes vary with environmental temperature and relative humidity, as well as with physical exercise.

13. E. Regulation of Water Output
1. The distal convoluted tubules of the nephrons and collecting ducts regulate water output.
2. Antidiuretic hormone from the posterior pituitary causes a reduction in the amount of water lost in the urine.
3. When drinking adequate water, the ADH mechanism is inhibited, and more water is expelled in urine.
The primary means of regulating water output is urine production. The distal convoluted tubules of the nephrons and collecting ducts are most important in regulating the volume of water excreted in the urine. The epithelial linings of these segments of the renal tubule remain relatively impermeable to water unless antidiuretic hormone (ADH) is present. ADH increase the permeability of the distal convoluted tubule and collecting duct, thereby increasing water reabsorption and reducing urine production. In the absence of ADH, less water is reabsorbed, and more urine is produced. (see chapter 17, p. 482).

14. Water Balance Disorders
Common disorders that reflect imbalance in the concentration of body fluids:
Dehydration – water output exceeds water intake
Water intoxication – too much water intake
Edema – abnormal accumulation of extracellular fluid within the interstitial spaces
In dehydration, water output exceeds water intake. Dehydration may follow excess sweating or prolonged water deprivation while water is still lost from the body. The extracellular fluid becomes increasingly more concentrated, and water leaves cells by osmosis. Dehydration may also accompany prolonged vomiting of diarrhea that depletes body fluids.
During dehydration, the skin and mucous membranes of the mouth feel dry, and body weight drops. Hyperthermia may develop as the body's temperature-regulating mechanism becomes less effective due to lack of water for sweat. Infant’s kidneys are less able to conserve water than those of adults, so infants are more likely to becomes dehydrated. Elderly people are also especially susceptible to developing water imbalances because the sensitivity of their thirst mechanism decrease with age, and physical disabilities may make it difficulty for them to obtain adequate fluids.
The treatment for dehydration is to replace the lost water and electrolytes. If only water is replaced, the extracellular fluid becomes more dilute than normal, producing a condition called water intoxication.
Babies rushed to emergency rooms because they are having seizures sometimes, have drunk too much water, a rare condition called water intoxication. This can occur when a baby under six months of age is given several bottles of water a day or very dilute infant formula. The hungry infant drinks the water, and soon its tissues swell with the excess fluid. When the serum sodium level drops, the eyes begin to flutter, and a seizure occurs. As extracellular fluid becomes hypotonic, water enters the cells rapidly by osmosis (see figures 18A, and 8B, slide 15). Coma resulting from swelling brain tissues may follow unless water intake is restricted and hypertonic salt solutions given. Usually, recovery is complete within a few days. Water intoxication caused the death of a fraternity member forced to drink gallons of water as an initiation test.
Edema is an abnormal accumulation of extracellular fluid within the interstitial spaces. Several factors cause edema, including decrease in the plasma protein concentration (hypoproteinemia), obstruction of lymphatic vessels, increase venous pressure, and increased capillary permeability (see Table 18A, slide 16).
Hypoproteinemia may result from liver disease that hinder plasma protein synthesis; kidney disease (glomerulonephritis) that damages glomerular capillaries, allowing proteins to enter urine; or starvation, in which amino acid intake is insufficient to support synthesis of plasma proteins. In each case, the plasma protein concentration decreases, which decreases plasma colloid osmotic pressure, reducing the normal return of tissue fluid to the venular ends of capillaries. Consequently, tissue fluid accumulates in the interstitial spaces.
Edema may result from lymphatic obstructions due to surgery or parasitic infections of lymphatic obstructions due to surgery or parasitic infections of lymphatic vessels (see chapter 14, p. 380).
Edema may also result from increase capillary permeability accompanying inflammation. Inflammation is a response to tissue damage and usually releases chemicals such as histamine from damaged cells. Histamine cause vasodilation and increased capillary permeability, so that excess fluid is filtered out of capillaries and enters interstitial spaces.
See chapter 18, pp

15. Figure 18A – if excess extracellular fluids are lost, cells dehydrate by osmosis.
Figure 18B – if excess water is added to the extracellular fluid compartment, cells gain water by osmosis.
Figure 18B
Figure 18A

16. Factors Associated with Edema
Table 18A summarizes the factors that can cause edema.

17. Figure 18.4 Water balance. a) Major sources of body water
b) Routes by which the body loses water. Urine production is most important in regulation of water balance.
Figure 18.4

18. Electrolyte Balance
A. An electrolyte balance exists when the quantities of electrolytes gained equals the amount lost.
B. Electrolyte Intake
1. The electrolytes of greatest importance to cellular metabolism are sodium, potassium, calcium, magnesium, chloride, sulfate, phosphate, bicarbonate, and hydrogen ions.
2. Electrolytes may be obtained from food or drink or produced as a by-product of metabolism.
Electrolyte balance exists when the quantities of electrolytes the body gains equal those lost. Homeostatic mechanisms maintain electrolyte balance.
The electrolytes of greatest importance to cellular functions dissociate to release sodium, potassium, calcium, magnesium, chloride, sulfate, phosphate, bicarbonate, and hydrogen ions. Foods provide most of these electrolytes, but drinking water and other beverages are also sources. Some electrolytes are by-products of metabolic reactions.

19. C. Regulation of Electrolyte Intake
1. A person ordinarily obtains sufficient electrolytes from foods eaten.
2. A salt craving may indicate an electrolyte deficiency.
D. Electrolyte Output
1. Losses of electrolytes occur through sweating, in the feces, and in urine.
Ordinarily, responding to hunger and thirst provides sufficient electrolytes. A severe electrolyte deficiency may produce a salt craving, a strong desire to eat salty foods.
The body loses some electrolytes by perspiring, with more lost in sweat on warmer days and during strenuous exercise. Varying amounts of electrolytes are lost in the feces. The greatest electrolyte output occurs as a result of kidney function and urine production. The kidneys alter electrolyte output to maintain balance.

20. E. Regulation of Electrolyte Output
1. The concentrations of sodium, potassium, and calcium, are very important.
2. Sodium ions account for 90% of the positively charged ions in extracellular fluids; the action of aldosterone on the kidneys regulates sodium reabsorption.
Precise concentrations of positively charged ions, such as sodium (Na+), potassium (K+), and calcium (Ca+2), are required for nerve impulse conduction, muscle fiber contraction, and maintenance of cell membrane potential. Sodium ions account for nearly 90% of positively charged ions in extracellular fluids. The kidneys and the hormone aldosterone regulate these ions. Aldosterone, which the adrenal cortex secretes, increase sodium ion reabsorption in the distal convoluted tubules of the kidney’s nephrons and collecting ducts.

21. 3. Aldosterone also regulates potassium
3. Aldosterone also regulates potassium ions; potassium ions are excreted when sodium ions are conserved.
4. Calcium concentration is regulated by parathyroid hormone, which increases the concentrations of calcium and phosphate ions in extracellular fluids and by calcitonin which does basically the reverse.
Aldosterone also regulates potassium ions. A rising potassium ion concentration directly stimulates the adrenal cortex to secrete aldosterone. This hormone enhances tubular reabsoprtion of sodium ions, and at the same time, causes tubular secretion of potassium ions.
Calcium ion concentration dropping below normal directly stimulates the parathyroid glands to secrete parathyroid hormone. This hormone returns the concentration of calcium in extracellular fluids toward normal.

22. 5. Generally, the regulatory mechanisms
5. Generally, the regulatory mechanisms that control positively charged ions (cations) secondarily control the concentrations of negatively charged ions (anions).
Generally, the regulatory mechanisms that control positively changed ions secondarily control the concentration of negatively changed ions. For example, renal tubules passively reabsorb chloride ions, the most abundant negatively charged ions in extracellular fluids, in response to active tubular reabsorption of sodium ions. That is, negatively changed chloride ions are electrically attracted to positively changed sodium ions and accompany them as they are reabsorbed (see chapter 17, p. 480).

23. Sodium and Potassium Imbalances
Extracellular fluids have high sodium ion concentration
Intracellular fluids have high potassium ion concentration
Renal regulation of sodium and potassium
Disorders result from imbalances
Extracellular fluids usually have high sodium ion concentrations, and intracellular fluid usually has a high potassium ion concentration. Renal regulation of sodium is closely related to that of potassium because secretion (and excretion) of potassium accompanies active reabsorption of sodium (under the influence of aldosterone). Therefore, conditions resulting from sodium ion imbalance often also involve potassium ion imbalance.
Such disorders include:
Low sodium concentration (hyponatremia)
High sodium concentration (hypernatremia)
Low potassium concentration (hypokalemia)
High potassium concentration (hyperkalemia)

24.  Acid-Base Balance
A. Electrolytes that ionize in water and release hydrogen ions are acids; those that combine with hydrogen ions are bases.
B. Maintenance of homeostasis depends on the control of acids and bases in body fluids.
Electrolytes that dissociate in water and release hydrogen ions are called acids and electrolytes that release ions that combine with hydrogen ions are called bases (chapter 2, pp ). Maintenance of homeostasis depends on controlling the concentrations of acids and bases within body fluids.

25. C. Sources of Hydrogen Ions
1. Most hydrogen ions originate as by- products of metabolic processes, including: the aerobic and anaerobic respiration of glucose, incomplete oxidation of fatty acids, oxidation of amino acids containing sulfur, and the breakdown of phosphoproteins and nucleic acids.
Most of the hydrogen ions in body fluids originate as by-products of metabolic processes, although the digestive tract may directly absorb small quantities. The major metabolic sources of hydrogen ions include the following (see figure 18.6, slide 26):
Aerobic respiration of glucose – This process produces carbon dioxide and water. Carbon dioxide diffuses out of cells and reacts with the water in extracellular fluids to form carbonic acid, which then ionizes to release hydrogen ions and bicarbonate ions.
Anaerobic respiration of glucose – Anaerobically metabolized glucose produces lactic acid, which adds hydrogen ions to body fluids.
Incomplete oxidation of fatty acids – This process produces acidic ketone bodies, which increase hydrogen ion concentration.
Oxidation of sulfur-containing amino acids – This process yields sulfuric acid (H2SO4), which ionizes to release hydrogen ions.
Breakdown (hydrolysis) of phosphoproteins and nucleic acids – Phosphoproteins and nucleic acids include phosphorus. Their oxidation produces phosphoric acid (H3PO4), which ionizes to release hydrogen ions

26. Figure 18.6 Metabolic processes that provide Hydrogen ions
Some of the metabolic processes the at provide hydrogen ions.
Figure Metabolic processes that provide Hydrogen ions

27. D. Strengths of Acids and Bases
1. Acids that ionize more completely are strong acids; those that ionize less completely are weak acids.
2. Bases release hydroxyl and other ions, which can combine with hydrogen ions, thereby lowering their concentration.
Acids that dissociate to release hydrogen ions more completely are strong acids, and those that dissociate to release hydrogen ions less completely are weak acids. For example, the hydrochloric acid (HCL) of gastric juice is a strong acid, but the carbonic acid (H2CO3) produced when carbon dioxide reacts with water is weak.
Bases release ions, such as hydroxide ions (OH-), which can combine with hydrogen ions and thereby lower their own concentration. Thus, sodium hydroxide (NaOH), which releases hydroxide ions, and sodium bicarbonate (NaHCO3), which releases bicarbonate ions (HCO3-), are bases. Strong bases dissociate to release more OH- or its equivalent than do weak bases. Often, the negative ions themselves are called bases. For example, HCO3- acting as a base combines with H+ from the strong acid HCL to form the weak acid carbonic acid (H2CO3).

28. E. Regulation of Hydrogen Ion Concentration
1. Acid-base buffer systems, the respiratory center in the brain stem, and the kidneys regulate pH of body fluids.
Acid-base buffer systems, the respiratory center in the brainstem, and the nephrons in the kidneys regulate hydrogen ion concentration in body fluids. The pH scale is used to measure hydrogen ion concentration.

29. 2. Acid-Base Buffer Systems. a. The chemical components of a
2. Acid-Base Buffer Systems a. The chemical components of a buffer system can combine with a strong acid and convert it to a weaker one.
b. The chemical buffer systems in body fluids include the bicarbonate buffer system, the phosphate buffer system, and the protein buffer system.
Acid-base buffer systems, in all body fluids, consist of chemicals that combine with excess acids or bases. More specifically, the chemical components of a buffer system can combine with strong acids, which release many hydrogen ions, converting them into weak acids, which release fewer hydrogen ions. Likewise, these buffers can combine with strong bases to convert them into weak bases. Such actions help minimize pH changes in body fluids. The three most important acid-base buffer systems in body fluids are:
Bicarbonate buffer system - In the presence of excess hydrogen ions, bicarbonate ions combine with hydrogen ions to form carbonic acid, thus minimizing any increase in the hydrogen ions concentration of the body fluids.
Phosphate buffer system – it is particularly important in the control of hydrogen ion concentrations in the tubular fluid of the nephrons and in urine.
Protein buffer system – protein molecules can function as bases by accepting hydrogen ions into their amino groups or as acids by releasing hydrogen ions from their carboxyl groups. This special property allows protein molecules to operate as an acid-base buffer system, minimizing changes in pH.
Table 18.1 summarizes the actions of the three major buffer systems.

30. Chemical Acid-Base Buffer System
Table 18.1 summarizes the actions of the three major buffer systems.

31. 3. The Respiratory Center
a. The respiratory center in the brain stem helps to regulate hydrogen ion concentration by controlling the rate and depth of breathing.
b. During exercise, the carbon dioxide, and thus the carbonic acid, levels in the blood increase.
c. In response, the respiratory center increases the rate and depth of breathing, so the lungs excrete more carbon dioxide.
The medullary respiratory center in the brainstem helps regulate the hydrogen ion concentration in body fluids by controlling the rate and depth of breathing (see figure 18.7, slide 32; and chapter 16, pp ). Specifically, if cells increase carbon dioxide production, as during physical exercise, carbonic acid production increases. As carbonic acid dissociates, the concentration of hydrogen ions increases, and the pH of the internal environment drops. Such an increasing concentration of carbon dioxide in the central nervous system and the subsequent increase in hydrogen ion concentration in the cerebrospinal fluid stimulate chemoreceptors in the medulla oblongata.
The respiratory center responds by increasing the depth and rate of breathing, so the lungs excrete more carbon dioxide. This returns the hydrogen ion concentration in body fluids toward normal because the released carbon dioxide comes from carbonic acid (H2CO3 – CO2 + H2O)
Conversely, if cells are less active, production of carbon dioxide and hydrogen ions in body fluids remains relatively low. As a result, breathing rate and depth stay closer to resting levels.

32. An increase in carbon dioxide production increase carbon dioxide elimination.
Figure 18.7

33. 4. The Kidneys 5. Rates of Regulation
a. Nephrons secrete excess hydrogen ions in the urine.
5. Rates of Regulation
a. Chemical buffers are considered the body’s first line of defense against shifts in pH; physiological buffer systems (respiratory and renal mechanisms) function more slowly and constitute secondary defenses.
Nephrons help regulate the hydrogen ion concentration of body fluids by excreting hydrogen ions in urine. Epithelial cells lining certain segments of the renal tubules secrete hydrogen ions into the tubular fluid (see chapter 17, p. 481).
The various regulators of hydrogen ion concentration operate at different rates. Acid-base buffers can convert strong acids or bases into weak acids or bases almost immediately. For this reason, these chemical buffer systems are sometimes called the body’s first line of defense against shifts in pH.
Physiological buffer system, such as the respiratory and renal mechanism, function more slowly and constitute the body’s second line of defense against shifts in pH. The respiratory mechanism may require several minutes to begin resisting a change in pH, and the renal mechanisms may require one to three days to regulate a changing hydrogen ion concentration.

34. Acid-Base Imbalances
A. Chemical and physiological buffer systems usually keep body fluids within very narrow pH ranges but abnormal conditions may prevent this.
1. A pH below 7.35 produces acidosis while a pH above 7.45 is called alkalosis.
Chemical and physiological buffer system generally maintain the hydrogen ion concentration of body fluids within very narrow pH ranges. The pH of arterial blood is normally 7.35— Abnormal conditions may disturb the acid-base balance. A pH value below 7.35 produces acidosis. A pH above 7.45 produces alkalosis. Such shifts in the pH of body fluids can be life-threatening. A persons usually cannot survive if the pH of body fluids drops to 6.8 or rises to 8.0 for longer than a few hours.
Acidosis results form an accumulation of acids or loss of bases, either of which increases the hydrogen ion concentration of body fluids. Conversely, alkalosis results from a loss of acids or an accumulation of bases accompanied by a decrease in hydrogen ion concentration.

35. 1. Two major types of acidosis are respiratory and metabolic acidosis.
B. Acidosis
1. Two major types of acidosis are respiratory and metabolic acidosis.
a. Respiratory acidosis results from an increase of carbonic acid caused by respiratory center injury, air passage obstructions, or disease processes that decrease gas exchange.
The two major types of acidosis are respiratory acidosis and metabolic acidosis. Factors that increase carbon dioxide concentration, also increasing the concentration of carbonic acid (the respiratory acid), cause respiratory acidosis. Metabolic acidosis is due to accumulation of any other acids in the body fluids or to loss of bases, including bicarbonate ions.
Respiratory acidosis may be due to hindered pulmonary ventilation, which increase carbon dioxide concentration. This may result from the following conditions:
Injury to the respiratory center of the brainstem, decreasing rate and depth of breathing.
Obstruction of air passages that interferes with air movement into alveoli.
Diseases that decrease gas exchange, such as pneumonia, or that reduce the surface area of the respiratory membrane, such as emphysema.
Any of these conditions can increase the level of carbonic acid and hydrogen ions in body fluids, lowering pH. Chemical buffers, such as hemoglobin, may resist this shift in pH. At the same time, rising concentrations of carbon dioxide and hydrogen ions stimulate the respiratory center, increasing the breathing rate and depth and thereby lowering the carbon dioxide concentrations. Also the kidneys may begin to excrete more hydrogen ions. Eventually, these chemical and physiological buffers return the pH of the body fluids to normal. The acidosis is thus compensated.
The symptoms of respiratory acidosis result from the depression of CNS function. They include drowsiness, disorientation, stupor, labored breathing, and cyanosis. In uncompensated acidosis, the person may become comatose and die.

36. b. Metabolic acidosis is due to. either an accumulation of acids or
b. Metabolic acidosis is due to either an accumulation of acids or a loss of bases, and has many causes including kidney disease, vomiting, diarrhea, and diabetes mellitus.
c. Increasing respiratory rate or the amount of hydrogen ions released by the kidney can help compensate for acidosis.
Metabolic acidosis is due to accumulation of nonrespiratory acids or loss of bases. Factors that may lead to this condition include the following:
Kidney disease that reduces glomerular filtration so that the kidneys fail to excrete acids produced in metabolic, (uremic acidosis.
In diabetes mellitus, metabolic reactions convert some fatty acids into ketone bodies, such as acetoacetic acid, beta-hydroxybutyric acid, and acetone.
Prolonged vomiting with loss of the alkaline contents of the upper intestine and the stomach contents. (Losing only the stomach contents produces metabolic alkalosis.) Vomiting can empty not only the stomach, but also the first foot or so of the intestine.
Prolonged diarrhea with loss of excess alkaline intestinal secretions (especially in infants).
In each case, pH is lowered. Countering this lower pH are chemical buffer systems, which accept excess hydrogen ions; the respiratory center, which increases breathing rate and depth; and the kidneys, which excrete more hydrogen ions.

37. Some of the factors that lead to metabolic acidosis
Figure 18.12

38. 1. Alkalosis also has respiratory and metabolic causes.
C. Alkalosis
1. Alkalosis also has respiratory and metabolic causes.
a. Respiratory alkalosis results from hyperventilation causing an excessive loss of carbon dioxide.
b. Metabolic alkalosis is caused by a great loss of hydrogen ions or from a gain in bases perhaps from vomiting or use of drugs.
The two major types of alkalosis are respiratory alkalosis and metabolic alkalosis. Respiratory alkalosis results from excessive loss of carbon dioxide and consequent loss of carbonic acid. Metabolic alkalosis is due to excessive loss of hydrogen ions or gain of bases.
Respiratory alkalosis develops as a result of hyperventilation, in which too much carbon dioxide is lost, consequently decreasing carbonic acid and hydrogen ion concentrations (see chapter 16, pp ). Hyperventilation may occur in response to anxiety or may accompany fever or poisoning from salicylates, such as aspirin. At high altitudes, hyperventilation may be a response to low oxygen partial pressure. Musicians can hyperventilate when providing large volume of air needed to play sustain passages on wind instruments. In each case, rapid, deep breathing depletes carbon dioxide, and the pH of body fluids increases (see figure 18.13, slide 39).
Chemical buffers, such as hemoglobin, that release hydrogen ions resist the increase in pH. The lower concentrations of carbon dioxide and hydrogen ions decrease stimulation of the respiratory center. This inhibits the hyperventilation, thus reducing further carbon dioxide loss. At the same time, the kidneys excrete fewer hydrogen ions, and the urine becomes alkaline as bases are excreted.
Symptoms of respiratory alkalosis include lightheadedness, agitation, dizziness, and tingling sensations. In severe cases, peripheral nerves may spontaneously trigger impulses, an muscles may respond with tetanic contractions (see chapter 8, p. 188).
Metabolic alkalosis results from a great loss of hydrogen ions or from a gain in bases, both of which increase blood pH (alkalemia). This condition may follow gastric drainage (lavage), prolonged vomiting of stomach contents, or use of certain diuretic drugs. Because gastric juice is very acidic, its loss leaves body fluids more basic. Metabolic alkalosis may also develop from ingesting too much antacid, such as sodium bicarbonate. Symptoms of metabolic alkalosis include decrease breathing rate and depth, which in turn increases the blood carbon dioxide concentration.

39. Some of the factors that lead to respiratory alkalosis.
Figure 18.13

40. Clinical Terms Related to Water and Electrolyte Balance
Acetonemia – excess acetone in blood.
Acetonuria – excess acetone in urine.
Albuminuria – albumin in urine.
Anasarca – widespread accumulation of tissue fluid.
Antacid – substance that neutralizes an acid.
Anuria – absence of urine excretion.
Azotemia – accumulation of nitrogenous wastes in blood.
Diuresis – increased urine production
Glucouria - excess sugar in urine
Hyperkalemia – excess potassium in the blood.
Hypernatremia – excess sodium in the blood.
Hyperuricemia – excess uric acid in the blood.
Hypoglycemia – abnormally low blood sugar level.
Ketonuria – ketone bodies in the urine.
Ketosis – acidosis due to excess ketone bodies in body fluids.
Proteinuria – protein in the urine.
Uremia – toxic condition resulting from nitrogenous wastes in the blood.
Clinical terms related to water and electrolyte balance.

41. What’s Next?
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