Quiz 2 Acid Base Flashcards
In chemistry, what is a conjugate pair?
A weak acid and its conjugate base
Or a weak base and its conjugate acid
What is an example of a conjugate pair?
Carbonic acid and Bicarbonate
What is the mathematical formula for pH?
it is the negative log of hydrogen ion concentration
What is pKa?
pKa is an equilibrium constant
What does the Ka stand for in pKa?
acid dissasociation constant
What does the pKa tell us about the acid?
1.how tightly the proton is held onto by the acid
2. how easily the acid donates a proton
A stronger acid would have a (lower/higher) pKa?
Lower
A weaker acid would have a (lower/higher) pKa?
higher
What is the pKa of blood?
6.1
What pH does the carbonic acid-bicarbonate buffer system work most effectively?
6.1
How does a chemical buffer system prevent radical/large/rapid changes in pH and maintain homeostasis?
by dampening changes in hydrogen ion concentration in the case of excess acid or base
What does the term buffer action mean?
The ability of an acid base mixture to resist sudden/radical/rapid changes in pH
How do buffers work against large changes in pH?
By releasing or binding hydrogen ions in response to pH changes. Excess hydrogen ions will bind with bicarb to form carbonic acid
What is the main/only blood buffer of clinical significance?
Carbonic acid-bicarbonate buffer system
Name 2 other buffer systems in the body in regards to acid base balance
Plasma protein buffer system
Phosphate buffer system
Explain how the plasma protein buffer system works
The plasma protein buffer system works by having proteins with charged amino acid side changes binding to excess hydrogen ions when pH is too acidic and releasing hydrogen when pH is too basic
Describe the phosphate buffer system
Phosphate acts as a buffer by combining with hydrogen ions
what is the ratio between bicarbonate and carbonic acid under normal conditions?
20:1
What are the 3 variables that determine the effectiveness of a buffer system
- the pK of the buffer
- The quantity of the buffer
- Whether or not the buffer is in an open or closed system
Describe an open system in relation to buffers
In an open system, the products of buffering do not accumulate because they can be exhaled
An acid can be thought of as a proton _______
Donator
A base can be thought of as a proton _________
Acceptor
What are the two characteristics of a weak acid?
- Does not completely dissociate in water
- Smaller K and Ka values, larger pK values
Describe how bicarb functions in an open system and explain what occurs when bicarb buffers a hydrogen ion
When bicarb buffers a hydrogen ion, it reacts with excess hydrogen ions to neutralize them and convert them into water and carbon dioxide
What does the p in pH stand for?
Power/potential
What does the H in pH stand for?
Hydrogen ion concentration
What does the p in pK stand for?
-log
What does the K in pK stand for?
dissociation constant
Describe the role of the lungs in acid/base homeostasis
The lungs are responsible for maintaining the concentration of carbonic acid at constant levels in arterial blood by excreting carbonic acid at the same rate as it is produced
How is carbonic acid formed?
CO2 enters the RBCs and combines with water to form carbonic acid. it is then broken down by carbonic anhydrase into H+ and bicarb with the H+ binding to the heme and the bicarb shifting out of the RBC
What is the significance of the ability of the lungs to excrete carbonic acid at the same rate as it is produced?
This allows for CO2 to continue to shift from the tissue into the RBC
How are the lungs able to change the amount of carbonic acid excreted?
By changing alveolar ventilation
What determines the rate of CO2 production?
BMR, Gender, Age, environmental variables, nutrition, physiologic trauma, exertion
What is the relationship between PCO2 and H2CO3?
Direct and linear
Why is venous blood slightly more acidic than arterial blood?
More CO2 from the tissues
Describe the relationship between the concentration of dissolved CO2 and the concentration of carbonic acid in the blood?
Direct and linear
What is the ration of carbonic acid to that of dissolved CO2 in the blood?
1:340
Why can PCO2 be used as a marker of volatile blood acid levels?
There is a direct and linear relationship between the 2
What is VCO2?
The amount of carbon dioxide produced by the tissues of the body
What is a normal minute VCO2?
250 ml/minute
Give three examples of conditions and or situation where it is important for clinicians to attempt to minimize CO2 production and/or increase ventilatory support to aid in CO2 excretion
1Ventilatory failure/hypercarbic failure/respiratory failure secondary to hypercarbia
2.CNS control of ventilation not intact
3. Paralysis of respiratory muscles due to injury or pharmacologic means
Given a current PaCo2 and minute alveolar ventilation, describe the formula used to calculate the change in minute alveolar ventilation and or respiratory rate
VE x PaCO2 = VE x PaCO2
How are fixed acids produced
In the cells secondary to incomplete metabolism of foodstuffs
Name 2 major fixed acids that are typically produced in predictable amounts in healthy people on a daily basis
Sulfuric acid
Phosphoric acid
Name two acids that are produced in increased amounts as the result of illness
Ketoacids
Lactic Acids
How are fixed acids excreted?
In the kidneys via the urine
What disease states can result in an increased production of fixed acids?
Chronic kidney disease
Renal tubular disease
