RS Lecture 9 and 10 - Acid Base Regulation and Sensory Aspects of Respiratory Disease Flashcards
What is alkalaemia?
Raised pH of blood
What is acidaemia?
Lowered pH of blood
What is alkalosis?
Describes circumstances that will decrease [H+] and increase pH
What is acidosis?
Described circumstances that will increase [H+] and decrease pH
What is the main equilibrium in the body?
H2O+CO2 H2CO3 H+ + HCO3-
What is the blood’s buffering capacity?
It is huge and reacts almost immediately to imbalances
What is the equation for pH and [H+]?
pH= –log10[H+] [H+]= 10^-pH
What are the 2 types of acids in the body?
Respiratory acid (CO2) and metabolic acid (pyruvic acid, etc)
What is the Henderson equation and the Henderson-Hasselbalch equation?
What can we tell from an arterial blood gas sample?
Changes in pH, PaCO2, PaO2, BE
What are the values for PaO2 in the blood?
>10kPa is normal, 8-10 mild hypoxaemia, 6-8 moderate hypoxaemia, and
What are the 2 compensatory mechanisms?
Changes in ventilation can stimulate a RAPID compensatory response to change CO2 elimination and thus alter pH. Changes in HCO3- and H+ retention/secretion in kidneys can stimulate a SLOW compensatory response to increase/decrease pH
How can you compensate acidosis/alkalosis?
Acidosis needs alkalosis. Alkalosis needs acidosis.
What are the 2 compensatory mechanisms for respiratory acidosis?
Acute: CO2 moves into RBC , to combine with H2O to from H+ and HCO3- which is transported via the AE1 transporter into the blood, where they join with the excess H+ to form conjugate acid, increasing pH Chronic: Increasing reabsorption of HCO3- in the nephron
How is metabolic alkalosis compensated for (graph)?
How is metabolic acidosis compensated for (graph)?
How is respiratory alkalosis compensated for (graph)?
How is respiratory acidosis compensated for (graph)?
What are the 4 basic disturbances and what do they cause?
Hypoventilation -> respiratory acidosis. Hyperventilation -> respiratory alkalosis. Diarrhoea -> metabolic acidosis. Vomiting -> metabolic alkalosis
How do you interpret ABG?
Type of imbalance (alkal/acidaemia); aetiology of imbalance (respiratory, metabolic or mixed); homeostatic compensation present (UC, PC, FC); oxygenation (hypoxaemia, normoxaemia, hyperoxaemia)
What are the normal values of [Hb], pH, PCO2, PO2, HCO3-, BE and standard BE?
How do you interpret blood gases? -> chart
Work out these acid-base problems:
What is the prevalence of cough, chest pain and shortness of breath as respiratory symptoms?
Cough -> 3rd most common complaint heard by GP. Chest pain -> most common pain for which medical attention is sought. SOB: 6-27% of general popn; 3% of visits to GP
What are some signs and symptoms that can be seen in respiratory diseases?
Symptoms: cough, chest pain, shortness of breath. Signs: hyperinflation of chest, dullness on percussion of chest wall, increased resp rate, reduced movement of chest wall
What is the physiologic/pathologic stimulus leading to conscious sensation pathway?
Sensory stimulus -> transducer (sensor) -> excitation of sensory nerve -> integration of CNS -> sensory impression (neurophysiology) => sensory impression -> perception -> evoked sensation (behavioural psychology)