Flashcards in Pulmonary Biochemistry Week 3 Deck (189)
True/False: Respiratory acidosis/alkalosis are always caused by abnormal function of the lung
FALSE - often but not always. For example, a person can have respiratory acidosis (increased PaCO2) but lungs are normal
On the davenport diagram, the x-axis represents ____ and the y-axis represents _____ therefore any point on the graph is a solution of the Henderson equation. Overall, the Davenport diagram tells you how blood will respond to changes in ______
pH, [HCO3-], PaCO2
Davenport diagrams reflect the presence of _______ buffers in the blood
non-volatile [presence of Hb mitigates increase in h+ caused by shifts in bicarbonate buffer system]
On a davenport diagram, a steeper buffer line of blood [the line reflecting the changes paCO2 have on pH and HCO3-], would indicate what?
more non-volatile buffering power [basically, with greater changes in PaCO2 there are slightly greater changes in HCO3- but lesser changes in pH so line is steeper]
Describe three non-pulmonary causes of acute respiratory acidosis
disruption in neural linkage driving breathing, central nervous system depression[drug OD, anesthesia], external enviro preventing normal breathing[heavy weight]
Name 5 pulmonary causes of acute respiratory acidosis
upper airway obstruction, severe asthma attack, COPD, severe pneumonia, severe pulmonary edema
Respiratory acidosis/alkalosis is caused by a pathological change in _____ whereas metabolic acidosis or alkalosis is caused by a pathological change in ______
With a decrease in CO2 in which direction will the equilibrium shift. How do Hb buffers play a role.
For reference, the rxns:
CO2 H+ + HCO3-
H+ + Hb H+Hb
The equilibrium will shift towards the left to produce more CO2. H+ will be lost, but this will be mitigated by Hb releasing H+.
______ is caused by an increase in central drive to breathe
True/False: For respiratory alkalosis to occur, the entire neuromuscular chain for breathing must be intact
What are four conditions that act as abnormal ventilatory stimuli to increase central drive to breathe?
1) arterial hypoxemia or hypoxia; 2) direct stimulation of pulmonary mechanoreceptors and chemoreceptors by lung dz; 3) chemical or physical factors that stimulate the medullary respiratory center; 4) psych factors
True/False: Most common pulmonary diseases can lead to respiratory alkalosis
Describe the three conditions of acute asthma that act as abnormal ventilatory stimuli to increase breathing
Stimulation of sense receptors; anxiety (psych); hypoxemia
Describe the three conditions of pulmonary embolus that act as abnormal ventilatory stimuli to increase breathing
stimulation of sense receptors; pain (psych); hypoxemia
Describe the four conditions of bacterial pneumonia that act as abnormal ventilatory stimuli to increase breathing
inflammatory debris [direct stimulation of mechano/chemo receptors]; fever [direct stimulation of mechano/chemoreceptors]; anxiety [psych], and hypoxemia and hypoxia
How does hypoxemia cause respiratory alkalosis?
The peripheral chemoreceptors in the carotid and aortic bodies begin to drive breathing when PaO2 falls below ~60mmHg [so then CO2 blown off]
The same diseases that cause respiratory alkalosis can cause respiratory acidosis. What two factors would allow the transition to acidosis to occur?
If the disease progresses to a point of severity when MUSCLE STRENGTH IS WEAKENED AND/OR LOAD IS INCREASED enough to "tip the balance"
Load=airflow resistance, lung stiffness, ventilatory requirement
Strength=central drive, neural linkage, resp muscles [4 abnormal ventilatory stimuli]
In end-stage liver disease, ________ is quite common. This disease leads to intrapulmonary shunting that causes low V/Q regions. Pt's will be _____ and have a high A-a gradient
hepatopulmonary syndrome, hypoxemic
Respiratory acidosis is caused by _______ via __________ whereas respiratory alkalosis is caused by ________ via _________
hypercapnia, alveolar hypovenilation, hypocapnia, alveolar hyperventilation
Describe what occurs when a strong acid is added to a blood sample [open to chamber containing CO2 gas at 40mmHg]
Reference rxn: CO2 H+ + HCO3-
Adding H+ will shift equilibrium to left. HCO3- consumed to consume of of added acid. PCO2 will remain at 40mmHg.
Describe what occurs when a strong base is added to a blood sample [open to chamber containing CO2 gas at 40mmHg]
Reference rxn: CO2 H+ + HCO3-
Strong base [A-] will react with H+ to form HA. Therefore, H+ used up. To replace H+, equilibrium shifted to the right. HCO3- increases. PCO2 remains at 40mmHg.
What are two main causes of hypobicarbonatemia [which leads to metabolic acidosis]?
increase in EAP, reduced net excretion due to renal defects
[increase in EAP can be due to derangements in gut function, derangements in metabolism, exogenous intoxicants]
Describe how diarrhea or laxative abuse is a gastrointestinal cause of metabolic acidosis.
Diarrhea and laxative abuse lead to an increase in stool volume which means a lot of HCO3- is lost from the body. The lower gut cells secrete more HCO3- to replace the lost HCO3- which leads to increased H+ secretion into the blood. The increased H+ secretion into the blood leads to blood HCO3- being consumed.
Metabolic acidosis is caused by an imbalance between _______ and ______
organic acid production, consumption
Normally, there is an incomplete metabolism of carbs and lipids. Carbs and lipids are metabolized to organic acids, but do not finish complete metabolism to A- and H+. What is needed to complete this metabolism?
What happens during hypoxia in regards to carb/lipid metabolism?
Carb lipid metabolism is incomplete so there is a build up of organic acids [along with protons]
examples -metabolic acidosis (strenuous exercise with volume depletion) and ketoacidosis (type I diabetes)
______ and _____ are two alcohols that get metabolized to acids and therefore are exogenous causes of metabolic acidosis
methanol, ethylene glycol [essentially dissociate into A- + H+ and will be EAP like]
How does vomiting or nasogastric drainage cause metabolic alkalosis?
H+ are being lost which means that upper GI is generating more H+ --> upper GI is secreting more HCO3- into the blood --> initially, body will dump HCO3- via urine to keep pH normal --> if vomiting/nasogastric drainage continues, will result in metabolic alkalosis
What two mechanisms are required for metabolic alkalosis to occur?
A generation mechanism [such as vomiting] and a maintenance mechanism [such as increase in renal threshold for HCO3- spillage]