Flashcards in Acid-Base (Moore) Deck (72)
What way does the oxygen dissociation curve shift when alkalotic?
LEFT (oxygen has a higher affinity for hemoglobin)
Since the oxygen dissociation curve shifts left in an alkalotic patient, what does this mean for their saturation?
They might have good pO2 and O2 saturation, but they are pallid or cyanotic
What does a right shift of the oxygen dissociation curve imply?
-Decreased affinity of O2 with hemoglobin
-Decrease O2 carried from lungs
-O2 given up more readily to the tissues
What are causes of right shift of oxygen dissociation curve?
1. Acidosis (decreased pH)
2. Elevated temperature
3. Hypercarbia (elevated CO2)
4. Increased DPG
What does a left shift of the oxygen dissociation curve imply?
-Increased affinity of O2 with hemoglobin
-Increased O2 carried from lungs
-O2 given up less readily in the tissues
What are the causes of a left shift of the oxygen dissociation curve?
1. Alkalosis (increased pH)
3. Hypocarbia (decreased CO2)
4. Decreased DPG
What are the 3 ways CO2 is transported and what are the % of each?
1. 7% in plasma
2. 23% carried in globin portion of hemoglobin
3. 70% as bicarbonate in the plasma
What does carbonic anydrase do?
It can either combine CO2 and water to make carbonic acid or take carbonic acid and make CO2 and H20
What kind of acid is carbonic acid?
How does the body prevent acidosis?
It takes a H ion from carbonic acid and buffers it with hemoglobin leaving bicarbonate ions
Where does bicarb move and in exchange for what?
Bicarb will move out of RBCs into plasma and Cl ion will move into the cell
In the lungs, what direction does the mass action equation move and what is the result of this ?
To the left to make CO2 to exhale
What is an acid and what is acidosis?
-pH under 7
-Gives up H ions
-pH under 7.35
What is a base and what is alkalosis?
-pH over 7
-Accepts H ions
-pH over 7.45
What is normal plasma pH?
Between 7.35 and 7.45
Cellular metabolism produces H ions from what?
Glucose, fatty acids, AA
How is acid/base balance maintained?
By controlling H ion concentration (body is very sensitive to small changes in H concentration)
What 3 systems are in place to maintain acid base balance?
What are buffers?
Chemicals that act quickly to temporary changes in H concentraion-- Minimize changes in overall pH by accepting H ions when pH falls (acidosis) or by donating H ions when pH rises (alkalosis)
Is H removed from body?
NOPE...just removed from solution
What are the 3 buffering systems in the body?
1. Carbonic acid-bicarbonate system
2. Phosphate system
3. Protein system (hemoglobin and plasma proteins)
What is the ratio of bicarb to carbonic acid needed to maintain a normal pH?
What are the functions of the buffering system?
1. Provide important and immediate responses to potential changes in pH
2. Prevent changes in pH until excess H ions can be excreted or bicarb levels can be resorted
What happens if the 20:1 ratio of bicarbonate to carbonic acid can't be maintained?
A change in pH will occur
Why is the respiratory system so important in the control of acid-base balance?
It can respond quickly (short term control of pH)
What happens when CO2 is dissolved in H20?
Bicarbonate is formed
By increasing the rate or depth of breathing and increasing the amount of CO2, the level of bicarb in the body...?
Will decrease...less CO2 means less bicarbonate
What effect does the renal system have on acid-base balance?
Long term control...regulates the secretion of bicarbonate ions and excreting acids via renal tubule cells
What are the 3 ways the renal tubule alters pH?
1. Secretes H ions into the filtrate, clearing the blood of excess acids and making the urine more acidic
2. Reabsorb bicarb ions
3. Produce new bicarb ions to augment the buffering of H ions in the blood