Regulation of Homeostasis by the Kidney: Acid-Base Balance Flashcards
What is the Henderson-Hasselbalch equation?
The Henderson-Hasselbalch equation is pH = pKa + log ([A-]/[HA]).
What is the equilibrium involving CO2, H2O, H2CO3, and HCO3-?
CO2 + H2O ⇌ H2CO3 ⇌ HCO3- + H+.
What does pH represent in the Henderson-Hasselbalch equation?
pH represents the acidity or alkalinity of a solution.
What is the role of the kidney in pH regulation?
The kidney regulates pH by reabsorbing or excreting bicarbonate ions (HCO3-) and hydrogen ions (H+).
What is the role of the lung in pH regulation?
The lung regulates pH by controlling the elimination of carbon dioxide (CO2), which affects the levels of carbonic acid (H2CO3) and bicarbonate ions (HCO3-).
What is the importance of pH control in the body?
pH control is important for maintaining homeostasis. The extracellular fluid (ECF) pH should be kept between 7.35 and 7.45. Deviations outside this range can lead to acidosis (acidaemia) or alkalosis (alkalaemia), affecting various body systems and potentially leading to severe complications.
What are the potential consequences of pH alterations outside the normal range?
pH alterations outside the normal range can result in coma, cardiac failure, circulatory collapse, and in extreme cases, death. Severe acidosis (pH < 6.8) or alkalosis (pH > 8.0) can be life-threatening.
What are the sources of acid generation in the body?
The sources of acid generation include carbolic (volatile) acids, which are produced from the metabolism of carbohydrates and fats, and non-carbolic (non-volatile) acids, which are generated from the metabolism of sulfur-containing amino acids.
How are carbolic acids eliminated from the body?
Carbolic acids are converted to CO2, which is eliminated by the lungs through the excretion of CO2.
How are non-carbolic acids eliminated from the body?
Non-carbolic acids are buffered with bicarbonate (HCO3-) before being eliminated by the kidneys through the excretion of H+.
What are the mechanisms involved in dealing with the acid (H+) load in the body?
The mechanisms include buffering with bicarbonate and HPO42-, elimination through increased respiratory drive to excrete CO2, and increased hydrogen ion secretion by the kidneys.
How does the renal system contribute to fluid and acid-base homeostasis?
The renal system plays a role in maintaining acid-base balance by secreting hydrogen ions and reabsorbing or excreting bicarbonate ions. It also helps control blood pressure, ECF osmolality, and fluid balance.
How does the cardiovascular system contribute to fluid and acid-base homeostasis?
The cardiovascular system helps maintain effective circulating volume, perfusion, and blood pressure, which are important for fluid and acid-base balance.
How does the respiratory system contribute to fluid and acid-base homeostasis?
The respiratory system plays a role in gas exchange and can adjust the respiratory rate to increase or decrease CO2 excretion, thereby helping regulate acid-base balance.
What is the purpose of homeostasis in relation to fluid and acid-base balance?
Homeostasis is the body’s ability to maintain stable conditions within a narrow range. It ensures that fluid and acid-base balance are kept within the appropriate limits for optimal physiological function.
Which parts of the nephron are involved in the renal excretion of acid load?
The proximal convoluted tubule and the intercalated cells of the cortical collecting ducts are the main sites involved in the renal excretion of acid load.
What is the most prevalent filtered buffer in the distal nephron when urinary pH is less than 5.8?
HPO4-2 (dihydrogen phosphate) is the most prevalent filtered buffer in the distal nephron when urinary pH is less than 5.8.
What is the major adaptive response to acid load in terms of ammonium excretion?
Ammonium excretion, both in the proximal collecting ducts and through direct diffusion of lipid-soluble ammonia, constitutes a major adaptive response to acid load.
How does a decrease in extracellular bicarbonate affect the tubular cellular pH?
A decrease in extracellular bicarbonate increases the gradient across the basolateral membrane for bicarbonate diffusion out of the cell, thereby lowering the tubular cellular pH.
What are the causes of metabolic acidosis (increased H+ concentration)?
Metabolic acidosis can be caused by loss of bicarbonate, diarrhea, diuretic therapy, ingestion of acid (such as aspirin, ethylene glycol, or methanol), endogenous acid production (such as lactic acidosis or ketoacidosis), and decreased acid excretion due to renal failure.
What are the causes of metabolic alkalosis (increased HCO3- concentration)?
Metabolic alkalosis can be caused by the loss of acid, such as through vomiting or loss of stomach acid.
What are the causes of respiratory acidosis (increased CO2 concentration)?
Chronic lung diseases such as COPD (Chronic Obstructive Pulmonary Disease) and pulmonary fibrosis can cause respiratory acidosis.
What are the causes of respiratory alkalosis (reduced CO2 concentration)?
Hyperventilation, which can be caused by factors such as anxiety or pneumonia, can lead to respiratory alkalosis.
What is a specific example of a condition causing respiratory alkalosis?
Acute bronchial asthma can lead to respiratory alkalosis.
