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Last Modified: October 30,
1998 (J. Crimando).
Blood Acid/Base Balance
Review 1.0
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Several events in maintaining blood plasma acid/base balance are linked. These "connections" should be learned and understood (be able to explain the basis for the connection) before continuing. The following exercise will help review the acid/base equilibrium of the bicarbonate buffer system:
1) As respiration rate increases (________-ventilation) the
levels of 
(
)
in blood will __________.
2) As respiration rate decreases (________-ventilation) the
levels of in blood will __________.
STOP: Why do #1 and 2 occur? Explain in your own terms.
3) As increases, more _____ + ions will accumulate causing the pH of blood to __________.
4) As decreases, less _____ + ions will accumulate causing the pH of blood to __________.
STOP: Why is blood pH and "linked"? Explain it using a balanced chemical equilibrium reaction.
5) As blood pH decreases (becomes more _______), the respiratory centers in the brainstem will become __________ which will cause respiration rate to __________.
6) As blood pH increases (becomes more _______), the respiratory centers in the brainstem will become __________ which will cause respiration rate to __________.
STOP: Review this "connection" between pH and respiration rate. Explain how blood levels affect respiration rate:
7) The lungs (respiratory system) are used to regulate levels of in blood while the __________ (________ system) are used to
regulate levels of 
in the blood.
STOP: Describe what each system does in order to alter these levels. Explain - HOW is each system doing this?
8) Two general sources of acid/base imbalances are termed __________ acidosis/alkalosis or __________ acidosis/alkalosis based on the cause of the imbalance. Two examples of this are:
a) ______-ventilation = increases = _______ blood 
= _______ blood pH = respiratory ______;
b)Excess _____+ or loss of _____- ions in blood = ______ blood pH = metabolic _______.
STOP: If you do not understand this or have to rely on your text, practice again then continue. . .
10) While _________ acidosis/alkalosis is compenstated by altering the activity of the lungs (also known as "____________ compensation"), ____________ acidosis/alkalosis is compensated for by altering the
activity of the ____________ (which is known as "____________ compensation").
Once you understand the basis for these connections, continue on to the Respiratory Assignment. . .
Answers for this are at the bottom of this page. . .
Answers. . .
1) As respiration rate increases (hyperventilation) the
levels of ()
in blood will decrease.
2) As respiration rate decreases (hypoventilation) the
levels of in blood will increase.
Increased ventilation removes carbon dioxide from the blood faster. Slowed ventilation causes more carbon dioxide to build up in blood. Think of what happens when you hold your breath (stop ventilating) - carbon dioxide builds up in the blood very quickly. When you begin breating again, you are removing or "blowing out" the built up carbon dioxide.
3) As increases, more H+ ions will accumulate causing the pH of blood to decrease.
4) As decreases, less H+ ions will accumulate causing the pH of blood to increase.
Elevated carbon dioxide levels pushes the equilibrium reaction to the right creating more H+ ions which lower the pH. As carbon dioxide levels decrease, the equilibrium reaction is pushed to the left which removes the H+ ions causing the pH to increase.
5) As blood pH decreases (becomes more acidic), the respiratory centers in the brainstem will become stimulated which will cause respiration rate to increase.
6) As blood pH increases (becomes more alkaline), the respiratory centers in the brainstem will become inhibited which will cause respiration rate to decrease.
In general, acids (H+ ions) are excitatory to neurons. As the carbon dioxide level in the blood increases, it also increases in the cerebrospinal fluid (CSF). This causes the pH to drop - especially in the brain (there is less buffering ability in CSF than in blood). The low pH (excess H+ ions) stimulates neurons in the medullary respiratory centers to fire more impulses to the diaphram to increase the rate and depth of breathing.
7) The lungs (respiratory system) are used to regulate levels of in blood while the kidneys (urinary system) are used to regulate levels of in the blood.
The respiratory system modulates carbon dioxide levels by increasing or decreasing ventilation. The urinary system modulates bicarbonate levels by selectively generating, retaining or excreting bicarbonate ions. The kidneys also regulate H+ ion excretion in response to blood carbon dioxide levels (higher blood carbon dioxide or lower blood pH == faster H+ excretion).
8) Two general sources of acid/base imbalances are termed respiratory acidosis/alkalosis and metabolic acidosis/alkalosis based on the cause of the imbalance. Two examples of this are:
a) hypoventilation = increases = increase blood = decrease blood pH = respiratory acidosis;
b) Excess H+ or loss of HCO3- ions in blood = decrease blood pH = metabolic acidosis.
10) While metabolic acidosis/alkalosis is compenstated by altering the activity of the lungs (also known as "respiratory compensation"), respiratory acidosis/alkalosis is compensated for by altering the
activity of the kidneys (which is known as "renal compensation").
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This page was created using 
Review written for BIO202 by:
Dr. J. Crimando
GateWay Community College Phoenix, AZ
Spring, 1998.