26. Fluid and Electrolyte Balance, Acid Base Balance

Major chemical buffer systems and pH change resistance

Acid-Base Balance

Chemical Buffers

Acidosis, Respiratory and Metabolic

 The bicarbonate buffer system is the primary buffer system for the ECF. Because the phosphate buffer system is present in low concentrations in the ECF (approximately one-sixth that of the bicarbonate buffer system), it is relatively unimportant for buffering blood plasma. However, it is a very effective buffer in urine and in ICF, where phosphate concentrations are usually higher. 

 Which of the following has the LEAST influence over the pH of blood plasma? 

Respiratory Acidosis, Respiratory Alkalosis, Metabolic Acidosis, Metabolic Alkalosis

Figure Animation Renal Regulation of of pH Balance

 They have little physiological effect on chemical reactions in cells. 

 Strong acids dissociate fully, and weak acids dissociate incompletely. 

 Weak acids only dissociate partially in solution. 

 When high in the body, they cause alkalosis. 

 Most acid is a result of ingestion with food. 

 Our bodies have few ways to deal with excess amounts of acids. 

Acid-Base Problems

Bicarbonate Buffer System

 low rate of insensible water loss from skin 

 The kidneys are immature at birth; they are approximately half as proficient at concentrating urine as mature kidneys. Infant kidneys are also inefficient in ridding the body of acids. 

 lower amount of fluid intake and output in infants 

 decreased surface area relative to body volume 

 Infants are more likely to experience problems regulating acid-base balance because of several factors, including __________. 

Small amounts of acids enter the body via ingested foods. However, most H+ ions originate as metabolic by-products or end products. For example, the breakdown of phosphorus-containing proteins, the anaerobic breakdown of glucose, fat metabolism, and the loading and transport of CO2 in the blood all serve as sources of hydrogen ions in the body.

 Most of the hydrogen ions in the body come from acidic substances in the foods we ingest. 

Acid Base Balance: Animation

The only organ of the body that can remove excess nonvolatile fixed acids is the kidney. Fixed acids are also called metabolic acids.

 The only organ(s) of the body that can remove excess nonvolatile fixed acids is/are the __________. 

 Normal arterial blood pH is 7.4, which is slightly alkaline. 

 Normal arterial blood pH is __________. 

Acidosis refers to high H+ concentration.

 Acidosis results in increasing levels of what ion? 

Acid Base Balance: Renal Regulation

The most important renal mechanism for regulating acid-base balance of the blood involves controlling blood bicarbonate (HCO3–) levels. This is achieved by conserving or generating HCO3– and excreting HCO3–.

generating new HCO3–

One way the kidneys maintain HCO3– balance is by __________.

Acid Base Balance: Bicarbonate Ion Buffer

Alkalosis, Respiratory and Metabolic

Decreased CO2 levels will increase blood pH. If one hyperventilates, the levels of CO2 drop to below normal levels and can cause respiratory alkalosis. Increased CO2 will lower blood pH. In response to high CO2 levels, the rate of and depth of breathing will increase in an effort to vent off excess CO2. If one is unable to breathe, CO2 levels increase, leading to respiratory acidosis.

 Hyperventilation can lead to __________. 

Acid Base Balance: Respiratory Regulation

 Hemoglobin is a protein located in red blood cells and is an example of the protein buffer system, which is pivotal in buffering intracellular fluids. 

 Because the phosphate buffer system is present in low concentrations in the ECF, it is relatively unimportant for buffering blood plasma. 

 The body’s protein buffer system is important as an intracellular buffer. 

 The most important buffer system of extracellular fluid, such as plasma, is the __________ buffer system. 

Buffers

The Kidney's Role in Acid Base Balance

 Hypoventilation causes a drop in pH. Breathing slowly increases PCO2. 

 Which condition would cause a drop in pH? 

Renal acid-base control is coupled to Na+ transport.

 Renal acid-base control mechanisms are coupled to __________. 

Compensation for Acid:Base Imbalance Respiratory

 Most of the buffering power of body fluids resides in cells, and most of this reflects the buffering activity of intracellular proteins. 

 The most important buffer system in the intracellular fluid compartment (ICF) is the __________ buffer system. 

Compensation for Acid:Base Imbalance Metabolic

Compensation of Respiratory and Metabolic Acidosis and Alkalosis

 Any arterial pH between 7.0 and 7.35 is considered physiological acidosis. 

 Any arterial pH between __________ is considered physiological acidosis. 

The most common cause of acid-base imbalance is respiratory acidosis, a result of elevated blood levels of CO2 due to shallow breathing, suffocation, or lung diseases that impede O2 and CO2 exchange.

 Someone who is suffocating would develop __________. 

Mechanisms to Control Acid-Base Homeostasis

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1. Introduction to A&P

2. Chemistry

3. Cells

4. Tissues

5. Integumentary System

6. Bones + Skeletal Tissues

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8. Joints

9. Muscles and Muscle Tissue

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15. Special Senses

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17. Blood

18. Cardiovascular System: the Heart

19. Cardiovascular System: Blood Vessels