Week 11: Acid Base Inbalance Flashcards
Exam 4
What is the pH scale described as?
Logarithmic, not linear
Solutions with an excess of hydrogen ions are ____in nature.
acidic
Solutions with an excess of hydroxide ions (OH-) are…
basic or alkaline in nature
What is defined as neutral in biologic fluids?
a pH of 7.40
How do body acids form? What do these body acids release?
Body acids form as the end products of protein, carbohydrate, and fat metabolism; these acids can release hydrogen ion.
Base
A base is a substance that accepts hydrogen ions;
Acid
an acid is a substance that donates hydrogen ions.
Body acids exist as what two forms:
- volatile acids
- nonvolatile acids
volatile acids
(substances that can be eliminated as carbon dioxide [CO2] gas)
nonvolatile acids
(substances that can be eliminated only by the kidney).
What is the sole volatile acid formed in the body?
The sole volatile acid formed in the body is carbonic acid (H2CO3), a weak acid
Weak acid
it does not easily release its hydrogen ion.
Examples of nonvolatile acids:
lactic acid, phosphoric acid, sulfuric acid, acetoacetic acid, and beta-hydroxybutyric acid.
Many nonvolatile acids are considered what?
Strong acids
Strong acids
They readily release their hydrogen ions.
How are nonvolatile acids eliminated/
Nonvolatile acids are secreted into the urine by the renal tubules in amounts of approximately 60 to 100 mEq of hydrogen per day, or about 1 mEq per kilogram of body weight.
The body has three mechanisms, or lines of defense, to maintain the acid–base balance:
(1) physiologic (chemical) buffer systems (bicarbonate, phosphate, hemoglobin, and protein), the first line of defense;
(2) respiratory acid–base control, the second line of defense; and
(3) renal acid–base control, the third line of defense.
Buffer systems
resist changes in pH and maintain pH within the normal range
ECF Plasma buffer system two components:
- carbonic acid bicarbonate
- protein hemoglobin
Most important intracellular buffers:
- phosphate and
- protein
WHat are the most important renal buffers:
- Ammonia
- Phosphate
What is the base component of the carbonic-bicarb buffer system
bicarbonate ion
What is the acid component of the carbonic-bicarb buffer system?
hydrogen ion
What do the lungs do with CO2 and how?
The lungs eliminate CO2 and can increase the amount of CO2 eliminated by increasing the rate and depth of ventilation.
What order do the buffering systems respond most to least rapidly?
- physiological buffering system
- lungs
- Kidney
How do kidneys augment the carbonic acid bicarbonate buffer system?
the kidneys augment the carbonic acid–bicarbonate buffer system by reabsorbing or regenerating bicarbonate in the renal tubules or excreting hydrogen into the urine.
How do proteins act in the protein buffering system?
All proteins can attach or release a hydrogen ion.
Where are most proteins located, what does this mean for protein buffering?
Most proteins are inside cells; hence protein-based buffering is primarily an intracellular buffer system.
Example of protein buffer?
Hemoglobin
As pH increases, what happens to hemoglobin?
pH increases, hemoglobin loses hydrogen ions, and the reverse happens when the pH decreases.
How does hemoglobin affect pH when it binds to CO2?
Hemoglobin binds to CO2 to form carbaminohemoglobin (HHbCO2)
The bound CO2 is transported to the lungs, where it is released from the body through ventilation.
Why is CO2 a potential acid?
Unbound CO2 can dissociate in water to form H2CO3, a weak acid.
Unbound CO2 can dissociate in water to form H2CO3, a weak acid.
What does hemoglobin do when binded to CO2?
By binding carbon dioxide, the hemoglobin is preventing CO2 from dissociating into carbonic acid;
it thereby prevents the release of excess H+ ions into the environment.
What is the bicarbonate-carbonic acid buffer functional within?
WIthin the kidney
What are the two additional buffer systems active within the renal tubules
- Phosphate buffer
- Ammonia buffer