Lecture 7 - Acid Base Regulation Flashcards
What is the normal range for extracellular fluid [H+], and what is the corresponding pH range?
The normal range for extracellular fluid [H+] is 36-44 mol/l, corresponding to a pH range of 7.35-7.45.
Describe the major sources of CO2 in the body and how it contributes to acid-base balance.
CO2 is produced as a result of dietary metabolism (20,000 mmol/day), and approximately 60 mmol [H+] per day comes from protein metabolism in the diet. The equilibrium between CO2, H2CO3, H+, and HCO3- helps maintain acid-base balance.
Explain the movement of gases within the vascular system and how it indicates acid-base homeostasis.
Gases move from areas of high partial pressure (pp) to low pp. Changes in partial pressure within the vascular system can indicate poor acid-base homeostasis.
Describe the transport of oxygen in the blood and how oxygen is transported in the body.
Oxygen enters the blood at the alveolar-capillary interface and is transported in blood either dissolved in plasma or bound to haemoglobin inside red blood cells (RBCs).
Explain the production of CO2 in tissues and its transport in the body, particularly in red blood cells.
In tissues, CO2 moves from cells into RBCs, where H2CO3 is formed and then dissociates into H+ and HCO3-. RBCs are major producers of HCO3-. In the lungs, HCO3- enters RBCs and combines with H+ to produce H2CO3, which dissociates into CO2 and H2O, and CO2 is exhaled.
What is a buffer, and how does it help maintain pH in the body?
A buffer is a combination of a weak acid (H2CO3) and its salt (HCO3-), which resists changes in pH by absorbing or releasing H+ ions.
Explain the role of bicarbonate reabsorption and regeneration in the nephron in maintaining blood buffering capacity.
Bicarbonate recovery and regeneration in the nephron help maintain blood buffering capacity. In cases where H+ cannot be excreted (due to renal disease), and HCO3- cannot be reabsorbed, acidosis may occur due to an equilibrium disturbance. Bicarbonate reabsorption is a vital part of this process.
What is the Henderson equation, and how does it relate to blood pH and the concentration of various components?
The Henderson equation describes the relationship between pH, H+, HCO3-, and ppCO2 in the blood. Changes in any of these components can affect blood pH, leading to acidosis or alkalosis.
What factors contribute to the development of acidosis or alkalosis in the body, and how are they assessed?
Acidosis can result from increased [H+] or ppCO2 or decreased [HCO3-], while alkalosis can result from decreased [H+] or ppCO2 or increased [HCO3-]. The acid-base status is assessed by measuring [H+], [HCO3-], and ppCO2 concentrations.
Explain the difference between metabolic and respiratory acid-base disorders and how they primarily affect [HCO3-] and ppCO2, respectively.
Metabolic acid-base disorders primarily impact [HCO3-], such as in diabetic ketoacidosis, where [HCO3-] decreases. Respiratory acid-base disorders primarily affect ppCO2, leading to increased (acidosis) or decreased (alkalosis) [H+].
How do the lungs and kidneys work together to maintain acid-base balance, and what is the rate of their responses?
The lungs and kidneys cooperate to maintain acid-base balance. Lungs provide a fast response by regulating ppCO2, while kidneys provide a slower response by regulating [HCO3-].
What are the major components measured in blood gases, and how are the values calculated?
Blood gas analyzers directly measure pH, ppCO2, and ppO2, calculating [HCO3-] based on these values. The components measured in blood gases include pH, ppCO2, and [HCO3-].
List the alterations in blood gases and bicarbonate levels in respiratory acidosis, respiratory alkalosis, metabolic acidosis, and metabolic alkalosis.
In respiratory acidosis, ppCO2 increases, while [HCO3-] remains normal. In respiratory alkalosis, ppCO2 decreases, and [HCO3-] is normal. In metabolic acidosis, [HCO3-] decreases, and ppCO2 is normal. In metabolic alkalosis, [HCO3-] increases, and ppCO2 is normal.
Explain how the respiratory and renal systems compensate for metabolic acid-base disorders.
In metabolic acidosis, breathing increases to decrease ppCO2. In metabolic alkalosis, breathing becomes shallow to increase ppCO2. Renal compensation in respiratory acid-base disorders involves excreting H+ and reabsorbing HCO3- in response to respiratory acidosis.
What are the roles of the lungs and kidneys in maintaining acid-base balance in the body?
The lungs respond rapidly by regulating ppCO2 to maintain acid-base balance. The kidneys respond more slowly by regulating [HCO3-].
