Lecture 78: Physiology - Acid-Base I PDF
Document Details
Uploaded by FruitfulIntegral
Wayne State University
Tags
Summary
This document discusses body fluid buffering and titration, focusing on the acid-base state of arterial blood and the role of various components in maintaining homeostasis. It provides information about pH regulation, buffering mechanisms, and the Henderson-Hasselbalch equation relevant for understanding acid-base balance.
Full Transcript
Lecture 78: Physiology - Acid-Base I, Body Fluid Buffering & Titration Body acid-base state: taken to mean the acid-base state of arterial blood or ECF, body is open system pH is highly regulated due to the optimal range of function for many enzymes, transporters, etc. Class 1 (volatile) acids: only...
Lecture 78: Physiology - Acid-Base I, Body Fluid Buffering & Titration Body acid-base state: taken to mean the acid-base state of arterial blood or ECF, body is open system pH is highly regulated due to the optimal range of function for many enzymes, transporters, etc. Class 1 (volatile) acids: only CO2, high metabolic production, removed via exhalation Class 2 (nonvolatile) acids: H3PO4 and H2SO4, lower metabolic production, removed via the kidney H2CO3 regulation: CO2 + H2O ←→ H2CO3 ←→ H+ + CO3- Increased pCO2 and decreased pH leads to an increase in respiration (ventilation decreases pCO2) Increased pCO2 and decreased pH lead to an increase in renal acid secretion (leads to acid excretion) COPD: impaired gas exchange in lungs leads to accumulation of carbonic acid Diabetic ketoacidosis: B-hydroxybutyrate and acetoacetate addition lead to acid surplus in body Titration curve Plots the concentration of added strong acid (or base) against the pH of the solution Buffer value is the slope of the titration curve at any given pH (more buffering near pka) Buffering Acetic acid can dissociate into H+ and Acetate (acetate is its conjugate base) For imidazole: pH = pKa + log ([Im] / ([B] - [Im])) Im is important b/c its pka is 7 (close to body pH 7.4) Hemoglobin in RBCs acts as a buffer due to high histidine content (36 His per tetramer) - Most CO2 is carried as HCO3- and most H+ is carried as HIm+ within RBCs - Bone is also a sink for acids/ bases HCO3-/ CO2 buffer system: under dual control by the lungs and kidneys - CO2 can dissolve in water, amount dissolved is proportional to pCO2 in the plasma - Henderson-hasselbalch for CO2: pH = pKa + log ( [HCO3-] / (0.03 * pCO2)) Davenport diagram
