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Phys. Exam 4 Acid Base Balance
Acid base balance
83
Physiology
Graduate
11/29/2010
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Term
normal pH of arterial blood:
 Definition
7.4
Term
normal pH of venous blood and interstitial fluid:
 Definition
7.35
Term
normal pH of intracellular fluid:
 Definition
7.0
Term
With alkalosis, aka alkalemia, arterial blood pH __ to above ___, meaning there are ___ hydrogen ions.
 Definition
- pH raises to above 7.45
- decreased hydrogen ions
Term
With acidosis, aka acidemia, arterial blood pH ___ to below ___, meaning there are ____ hydrogen ions.
 Definition
- pH drops to below 7.35
- increased hydrogen ions
Term
when referring to alkalosis or acidosis, we are talking about ___ blood.
 Definition
arterial
Term
Venous blood is more ___ b/c increased amounts of ___.
 Definition
- acidic
- CO2
Term
Most hydrogen ions originate from ___ ___.
 Definition
- cellular metabolism
Term
Hydrogen originates from the following processes involved in cellular metabolism:
 Definition
- breakdown of phosphorous containing proteins releases phosphoric acid into ECF
- transporting carbon dioxide as bicarbonate releases hydrogen ions
- anaerobic respiration of glucose produces lactic acid
- fat metabolism yiedls organic acids and ketone bodies
Term
Hydrogen ion concentration is regulated sequentially by what three mechanisms:
 Definition
- chemical buffer system- acts within seconds
- respiratory center in brain stem- acts within 1-3 minutes, regulates frequency and depth of breathing to regulate blood CO2 levels
- renal mechanisms- requires hours to days to effect pH changes
Term
The chemical buffer system is composed of molecules that act to resist pH changes when strong acid or base is added. List the three components of the chemical buffer system. Any drifts in pH are resisted by the ___ ___ buffering system.
 Definition
- bicarbonate buffer system
- phosphate buffer system
- protein buffer system

- entire chemical buffering system
Term
The chemical buffer system ALWAYS contains a ___ ___ and its ___. Give an example.
 Definition
- weak acid and its salt
- carbonic acid (H2CO2) and sodium bicarbonate (NaHCO3) are the major buffer system in the intracellular fluid
Term
The ___ buffer system is the most important extracelluar buffer.
 Definition
- bicarbonate
- CO2/HCO3-
Term
HCO3-(bicarbonate) and CO2 are regulated by the ___ and ___ respectively.
 Definition
- kidneys and lungs
Term
normal ratio of CO2/HCO3- in extracellular fluid :
 Definition
1:24. This ratio helps maintain our arterial pH at 7.4
Term
The phosphate buffer system is an important ___ fluid buffer and ___ buffer.It is also important for buffering ___. This system is nearly identical to the ___ system.
 Definition
- intracellular
- urine
- hemoglobin
- bicarbonate
Term
Components of the phosphate buffer system:
 Definition
- sodium salts of dihydrogen phosphate (H2PO4-), a weak acid
- monohydrogen phosphate (HPO4-2), a weak base
Term
The protein buffer system is made up of ___ and ___ proteins.
 Definition
- plasma and intracellular
Term
__ and ___ ___ are the bodies most plentiful and powerful buffers.
 Definition
Plasma and intracellular proteins
Term
Some proteins have amino acids that are free organic acid groups that act as a ___ ___, while others have amino acids that act as a ___ ___ due to __ groups. ___ molecules are protein molecules that can function as both a weak acid and a weak base.
 Definition
- weak acid
- weak base via amino groups
- Amphoteric
Term
The respiratory system regulation of acid base balance is a ____ buffering system. There is a reversible equillibrium b/w dissolved ___ ___ and ___ and ___ ___ and __ and ___ ___.
 Definition
- physiological
- dissolved CO2 and water
- carbonic acid and hydrogen and bicarbonate ions

CO2 + H2O <> H2CO3 <> H+ + HCO3-
Term
So high levels of CO2, leads to increased ___ __, which leads to increased concentration of ___ ___, which ___ pH.
 Definition
- carbonic acid
- hydrogen ions
- decreases
Term
During carbon dioxide unloading, hydrogen ions are incorporated into ____.
 Definition
water
Term
When hypercapnia (increased CO2) or rising plasma H+ occurs, breaths become ___ and ___ __to expel more CO2. This ___ hydrogen ion concentration.
 Definition
- deeper
- more rapid
- reduces
Term
So acidosis causes:
 Definition
hyperventilation to get rid of excess CO2
Term
Alkalosis cuases ___, ___ ___ breathing, causing ___ to increase.
 Definition
- slower, more shallow
- H+
Term
Respiratory system impairement causes __ ___ ____.
 Definition
acid-base imbalance
Term
Chemical buffers can tie up excess acids or bases, but they cannot ___ them from the body.
 Definition
- eliminate
Term
The lungs can eliminate ___ ___ by eliminating ___ ____.
 Definition
- carbon dioxide
- carbonic acid
Term
Only the kidneys can rid the body of ___ ___ (phosphoric, uric, lactic, ketones) and prevent metabolic ____.
 Definition
- metabolic acids
- prevent metabolic acidosis
Term
The ultimate acid-base regulating organs:
 Definition
kidneys
Term
The most important renal mechanisms for regulating acid-base balance are:
 Definition
- Conserving via reabsorbing or generating new bicarbonate ions
- Excreting bicarbonate ions
Term
Losing a bicarbonate ion is the same thing as ___ a hydrogen ion. Likewise, reabsorbing a bicarbonate ion is same as ___ a hydrogen ion.
 Definition
- gaining
- losing
Term
Bicarbonate is reabsorbed in ___ ___ of the renal tubules and is always related to ___ ___.
 Definition
- all sections
- hydrogen secretion
Term
Reabsorption of bicarbonate in the proximal tubule and loop of Henle: ___ ___ formed in filtrate dissociates to release __ __ and ___. __ __ then diffuses into __ __, where it acts to trigger further __ __ ___.
 Definition
- Carbonic acid
- carbon dioxide and water
- carbon dioxide
- tubule cells
- hydrogen ion secretion
Term
___ ___, an enzyme in epithelial tubule cells, causes the CO2 to react with ___ to form ___ ___, which then dissociates into ___ ions and ___. They hydrogen ions get __ into the filtrate, while the bicaronate gets absorbed by capillaries. This is how bicarb reabsorption, furthers hydrogen secretions.
 Definition
- Carbonic anhydrase
- water
- carbonic anhydrase
- hydrogen ions and bicarbonate
- secreted
Term
Go through all steps in sequential order of bicarbonate reabsorption in the proximal tubule and loop of Henle:
 Definition
- carbonic acid in filtrate > (carbonic anhydrase)> water and CO2> CO2 diffuses into tubule epithelial cells> (carbonic anhydrase and water)> carbonic acid> breaks down into hydrogen ions and bicarbonate> hydrogen ions get secreted into tubule lumen> bicarbonate get reabsorbed by capillaries

(this can happen in tubule cells or epithelial cells)
Term
If the blood is slightly acidic, you will have more ___ ___ so more bicarbonate will be reabsorbed to bring pH back to normal.
 Definition
- carbonic anhydrase
Term
In the distal tubule _ ___ ___ are the hydrogen secreting cells, while __ ___ ___ are the bicarbonate secreting cells.
 Definition
- A intercalated cells
- B intercalated cells
Term
Reabsorption of bicarbonate in distal tubule is very similar to mechanism in proximal tubule.Reabsorption of bicarb and secretion of hydrogen here occurs in 1:1 ratio. This occurs in a normal state, but during ___ this mechanism is more acitve.
 Definition
acidosis
Term
With acidosis, there is a hydrogen ion graident and you want to secrete hydrogen and absorb bicarbonate. So there will be (4):
 Definition
- hydrogen gradient
- increased activity of transporters
- increased membrane expression of transporters
- long term increase in synthesis of transporters
Term
Hormones involved in regulation of H+ secretion:
 Definition
- Endothelin-1
- Cortisol
- Angiotensin II
- Aldosterone
Term
Formation of new bicarbonate in the kidneys involves renal excretion of acid via ___ and ___ of ___ ___ (__) or ___ ___ (__).
 Definition
- titrable acid (phosphate)
- ammonium ions (NH4+)
Term
So to make new bicarbonate the kidneys must secrete and excrete ___ __ and ___ ___.
 Definition
- titrable acid (phosphate)
- ammonium ions (NH4+)
Term
Hydrogen ion excretions as titrable acids occurs in ___ ___ in response to ___. The kidneys generate ___ ions and add them to blood, while an equal amount of ___ __ are added to the urine.
 Definition
- intercalated cells
- acidosis
- bicarbonate
- hydrogen ions
Term
In the ___ tubule, each ___ metabolized produces ___ ___ ___ and ___ ___ ___. The ___ moves to the blood and the ___ ___ are excreted in the urine.
 Definition
- proximal
- glutamine
- 2 ammonium ions
- 2 bicarbonate ions
- bicarbonate
- ammonium ions
Term
ammonium ion excretion happens in the ___ ___ and ___ ___.
 Definition
proximal tubule
collecting duct
Term
The ascending limb of the loop of Henle is permeable to ___ ___. So ___ __ come of the ascending limb of the loop of henle and into the ___ __, and then into the ___ ___ for excretion.
 Definition
- ammonium ions
- ammonium ions
- interstitial fluid
- collecting duct
Term
Ammonium ions can be pumped into a collecting duct cell from blood via the ___ __ ___ ____. Likewise, ammonium ions are pumped from the collecting duct cell into the collecting duct lumen via a ___ __ ___ ___
 Definition
- ammonium ion hydrogen antiporter.
- ammonium ion hydrogen antiporter
Term
Ammonium ions are formed in the ___ ___ from the metabolism of ___. They get pumped out of the proximal tubule cell and into the tubule lumen by ___ __ ___ ____.
 Definition
- ammonium ion sodium antiporters
Term
Secretion of ammonium ions in the proximal tubule and collecting duct is coupled to ___ ___.
 Definition
bicarbonate secretion
Term
The major site for secretion of hydrogen and ammonium ions is the ___ ___.
 Definition
proximal tubule
Term
When the body is in alkalosis, ___ ___ ___ cells exhibit ___ ___ secretion and ___ ___ ___ to acidify the blood.
 Definition
- type B intercalated cells
- bicarbonate ion secretion
- reclaim hydrogen ions
Term
The mechanism of type B intercalated cells that secrete bicarbonate and reclaim hydrogen is the opposite of type A intercalated cells.
 Definition
Term
Even duriing alkalosis, the nephrons and collecting ducts conserve more bicarbonate ions than they secrete.
 Definition
Term
4 types of acid base imbalance:
 Definition
- metabolic acidosis
- metabolic alkalosis
- respiratory acidosis
- respiratory alkalosis
Term
respiratory acidosis and alkalosis result from:
 Definition
failure of the respiratory system to balance pH
Term
___ is the single most important indicator of respiratory inadequacy.
 Definition
PCO2
Term
normal PCO2 fluctates between:
 Definition
35 and 45 mmHg
Term
Values of PCO2 above 45 mmHg indicate:
 Definition
respiratory acidosis
Term
Values of PCO2 below 35 mmHg indicate:
 Definition
- respiratory alkalosis
Term
___ ___ is the most common cause of acid-base imbalance. This occurs when a person breathes ___ or when gas exchange is impaired by diseases like ___, ___ ___, or ___.
 Definition
- Respiratory acidosis
- shallowly
- pneumonia
- cystic fibrosis
- emphysema
Term
hypoventilation causes:
 Definition
respiratory acidosis, pH less than 7.35
Term
Hyperventilation causes ___ ___.
 Definition
respiratory alkalosis, pH greater than 7.45
Term
___ ___ ___ ___ account for all pH imbalances except those caused by abnormal blood carbon dioxide levels.
 Definition
- Mebabolic acid-base imbalance
Term
With metabolic acid-base imbalance, ___ ___ levels fall above or below normal which is ___.
 Definition
- bicarbonate ion
- 22-26 mEq/L
Term
___ ___ is the second most common cause of acid base imbalance.
 Definition
Metabolic acidosis
Term
Typical causes of metabolic acidosis:
 Definition
- too much alcohol consumption and excessive bicarbonate loss
- accumulation of lactic acid
- shock
- ketosis in diabetic crisis
- starvation
- kidney failure
Term
Less than 22mEq/L of bicarbonate would be ___ ___.
 Definition
metabolic acidosis

(b/c not enough base)
Term
More than 24 mEq/L of bicarbonate ion would be ___ ___.
 Definition
- metabolic alkalosis

(b/c too much base)
Term
Rising blood __ and __ ___ indicate ___ ___.
 Definition
- rising blood pH and bicarbonate
- metabolic alkalosis
Term
Typical causes of metabolic alkalosis:
 Definition
- vomiting of the acid of stomach
- intake of excessive base from antacids
- constipation, in which excessive bicarbonate is reabsorbed
Term
The cause cannot correct itself. So metabolic acid-base imbalances will be corrected by the ___ ___, while respiratory acid base imbalance will be corrected by the ___.
 Definition
- respiratory system
- kidneys
Term
plasma pH is determined by what ratio?
 Definition
CO2/HCO3-

(lungs determine CO2)
(kidneys determine HCO3-)

don't forget this:

CO2 + H2O > (carbonic anhydrase)> H2CO3 > HCO3- + H+
Term
In metabolic acidosis, blood pH is below ___ and bicarbonate levels are ___. The ___ system compensates by ___ rate and depth of breathing to ___ CO2 levels, eventually ___ falls below normal. Ultimately normal pH and ratio of ____ is reached again.
 Definition
- 7.35
- low
- respiratory
- increasing
- decrease
- PCO2
- 1:24
Term
decrease in pH with metabolic acidosis activates the ____ in the ___ bodies.
 Definition
- chemoreflex
- carotid bodies (sense excess hydrogen)
Term
With metabolic alkalosis pH is over ___ and there are ___ bicarbonate levels. The ___ ___ compensates by causing ___ ___ breathing, which allows ___ __ to accumulate in the blood.
 Definition
- 7.45
- elevated
- respiratory system
- slow, shallow
- carbon dioxide
Term
With respiratory alkalosis you have too much bicarbonate and too little hydrogen in the blood, so the ___ reflex will be ___ causing you to breathe more slowly and shallow to allow CO2 to increase in plasma.
 Definition
- chemoreflex
- inhibited
Term
with metabolic alkalosis, the respiratory compensation causes ___ PCO2.
 Definition
rising
Term
with metabolic acidosis, the respiratory compensation causes ____ PCO2.
 Definition
decreasing
Term
With respiratory acidosis the pH is less than 7.35 and there are high ___ and ___ levels. The high ___ is the cause of acidosis. The high ___ level indicates the kidneys are retaining ___ to offset the acidosis.
 Definition
- PCO2 and bicarbonate
- PCO2
- bicarbonate
- bicarbonate
Term
With respiratory alkalosis, there is a __ __ and __ ___. To compensate, the kidneys ___ bicarbonate by ___ or by failing to __ it.
 Definition
- high pH
- low PCO2
- eliminate
- active secretion
- reclaim
Term
with respiratory alkalosis the pH is :
 Definition
- greater than 7.45
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