Download Acids

Lab 8 - Urinalysis, pH, &
Acid-Base Balance
week 1 of 2
pH and Acid-Base Balance – lab 1 of 2
Section 1
1. Essentials of pH
2. Acids vs. Bases and their sources
-----Section 2
1. pH of Body Fluids – the #s
2. Methods of Maintaining proper pH
Essentials of pH
•
•
•
•
•
•
•
Based on the # or conc. of free H+. [H+]
The actual #s are ridiculous. 0.0000001, 0.000001, etc.
If take –log of 0.0000001 it becomes 6, 7, etc
pH is the negative log of the H+ concentration
Scale is 0-14
Smaller # means more free H+
Each whole number means 10X difference in [H+]
The pH Wedgie
14
12
OH-
10
Alkaline
8
Neutral
6
H+
4
2
0
Acidic
Acids
•
•
Anything that ‘donates’ free H+ or binds up free OHExamples:
HCl → H+ + ClH2CO3 → _______________
LA →
Ketoacids →
FAs →
OHAAs →
Uric acid →
H+
Bases
•
Anything that binds up free H+ or donates free OH-
•
Examples
HCO3- binds with H+ in blood
NH3 binds with H+ in urine
HPO42- binds with H+ in urine
Most proteins bind up free H+
OH-
H+
We are ‘Acid Factories’
Constant production of H+ from
1) Catabolism of carbs (glycolysis)
If aerobic, CO2 produced….
If anaerobic, LA produced
2) Catabolism of lipids
FAs → ketoacids
3) Catabolism of proteins
Proteins → AAs →phosphoric acid & sulfuric acid
4) Acidic Foods (lemons, limes, oranges, grapefruit, vinegar,
tomatoes, soft drinks)
5) Stomach produces HCl acid
So, our pH is usually tending to _____
…a condition called ____________
End of section 1
pH of Arterial Blood
0
1
2
3
4
5
7
Normal
range
Acidosis
6.8
6
7.35
8
9
10
11
Alkalosis
7.45
7.8
12
13
14
Why be concerned about pH?
• All functional proteins are pH sensitive
– Enzymes, hormones, Hb, etc
• Therefore, all metabolic reactions are pH sensitive
3 Methods of Maintaining Proper pH
1) Chemical Buffers (buffer systems)
– Substances that temporarily bind up free H+ when in
excess and release it when deficient
– Fastest (secs)
– But limited capacity
Strange but true…
– Do NOT eliminate H+ from body
– Do NOT adjust pH
– Do NOT prevent a pH change
– DO resist or minimize pH changes
• pH still changes… just not so dramatically
3 Methods of Maintaining Proper pH
2) Respiratory Adjustments
– Adjusts pH by adjusting amount of C02 in blood
• and therefore H2CO3
• And therefore H+ + HCO3– Fast (1-3 min)
– But limited capacity
– Does NOT eliminate H+ from the body
3 Methods of Maintaining Proper pH
3) Renal Adjustments
–
–
–
–
–
Adjusts pH by adjusting secretion of H+
Adjusts pH by adjusting reabsorption of HCO3Sloooow (hours)
But unlimited capacity
Is the only one to actually get H+ out of body
Ta Da!
pH and Acid-Base Balance – lab 1
Section 1
1. Essentials of pH
2. Acids vs. Bases and their sources
-----Section 2
1. pH of Body Fluids – the #s
2. Methods of Maintaining proper pH