205 L4 Flashcards
Acid Base physiology
Molecules containing hydrogen atoms that can release hydrogen ions in solutions are referred to as —-.
Acids
A —- is an ion or a molecule that can accept an H+
Base
Proteins in the body also function as ——- because some of the amino acids that make up proteins have a net —— charge that readily accepts H+.
Proteins in the body also function as base because some of the amino acids that make up proteins have a net negative charge that readily accepts H+.
What is the normal pH of atrial blood?
7.4
Is the pH of venous blood and interstitial fluid above the normal atrial blood pH or below?
Below because of the extra amounts of carbon dioxide released from the tissues to form H2CO3 in these fluids.
Is the pH of venous blood and interstitial fluid above the normal atrial blood pH or below?
Below because of the extra amounts of carbon dioxide released from the tissues to form H2CO3 in these fluids.
A person is considered to have acidosis when the pH falls below ——- (addition of H+) and to have alkalosis when the pH rises above —– (removal of H+)
A person is considered to have acidosis when the pH falls below 7.4 (addition of H+) and to have alkalosis when the pH rises above 7.4 (removal of H+)
Name the mechanisms of pH control from immediate reaction to slow reaction.
Acid-Base buffer system
Respiratory center
Kidneys
Acid base buffer system
The chemical acid-base buffer system of the body fluids, immediately combine with —- or —- to prevent excessive changes in —- concentration.
This is the —- line of defense.
When there is a change in — concentration, the buffer systems of the body fluids react within seconds to —— these changes.
Buffer systems do not eliminate —- from or add them to the body but only keep them tied up until balance can be re-established.
The chemical acid-base buffer system of the body fluids, immediately combine with acid or base to prevent excessive changes in H+ concentration.
This is the first line of defence.
When there is a change in H+ concentration, the buffer systems of the body fluids react within seconds to minimise these changes.
Buffer systems do not eliminate H+ from or add them to the body but only keep them tied up until balance can be re-established.
Acid base buffer system
The chemical acid-base buffer system of the body fluids, immediately combine with —- or —- to prevent excessive changes in —- concentration.
This is the —- line of defense.
When there is a change in — concentration, the buffer systems of the body fluids react within seconds to —— these changes.
Buffer systems do not eliminate —- from or add them to the body but only keep them tied up until balance can be re-established.
The chemical acid-base buffer system of the body fluids, immediately combine with acid or base to prevent excessive changes in H+ concentration.
This is the first line of defence.
When there is a change in H+ concentration, the buffer systems of the body fluids react within seconds to minimise these changes.
Buffer systems do not eliminate H+ from or add them to the body but only keep them tied up until balance can be re-established.
The respiratory center
Regulates the removal of —— and therefore ——–, from the ——— fluid.
This is the ——- line of defence.
Regulates the removal of CO2 and therefore H2CO3, from the extracellular fluid.
This is the second line of defence.
The kidneys
Can excrete either —– or —– urine, thereby readjusting the ———- fluid — concentration toward normal during acidosis or alkalosis.
This is the last line of defense
Although the kidneys are relatively slow to respond compared with the other defenses, over a period of hours to several days, they are by far the most powerful of the acid—base regulatory systems.
Can excrete either acidic or basic urine, thereby readjusting the extracellular fluid H+ concentration toward normal during acidosis or alkalosis.
This is the — line of defense
The more ——– ions the greater the pH.
The more bicarbonate ions (HCO3-) the greater the pH (pH is directly proportional to HCO3-)
Higher ——- the lower the pH
Higher Pco2 the lower the pH (pH is inversely proportional to Pco2)
Name the buffer systems.
Bicarbonate buffers
phosphate buffers
Proteins
———- buffers are ubiquitous, act fast to sort out pH but are not strong.
Bicarbonate buffers
——– buffers are limited to the kidney tubules but are strong buffers
Phosphate buffers
Bicarbonate buffer
H2CO3 is an unstable compound so it breaks down into __ and ____
If there is an increase in _, they will combine with ______ to produce ____ which will then dissociate into ____ and ____, catalysed by —– —–. (breathe faster to remove CO2)
For alkalines (NaOH) combines with H2CO3 to form an inert compound (NaHCO3) and water.
Bicarbonate buffer system to be powerful, for two reasons:
First, the pH of the extracellular fluid is about 7.4, whereas the pK of the bicarbonate buffer system is 6.1 (the best pH at which the buffer exists as both a base and acid). This means that there is about 20 times as much of the bicarbonate buffer system in the form of HCO3 (acidic)— as in the form of dissolved CO2 (basic). For this reason, this system operates on the portion of the buffering curve where the slope is low and the buffering power is poor.
Second, the concentrations of the two elements of the bicarbonate system, CO2 and HCO3, are not great.
H2CO3 is an unstable compound so it breaks down into H+ and HCO3-
If there is an increase in H+, they will combine with bicarbonate to produce H2CO3 which will then dissociate into CO2 and H20, catalysed by carbonic anhydrase. (breathe faster to remove CO2)
For alkalines (NaOH) combines with H2CO3 to form an inert compound (NaHCO3) and water.
Bicarbonate buffer system to be powerful, for two reasons:
First, the pH of the extracellular fluid is about 7.4, whereas the pK of the bicarbonate buffer system is 6.1 (the best pH at which the buffer exists as both a base and acid). This means that there is about 20 times as much of the bicarbonate buffer system in the form of HCO3— as in the form of dissolved CO2. For this reason, this system operates on the portion of the buffering curve where the slope is low and the buffering power is poor.
Second, the concentrations of the two elements of the bicarbonate system, CO2 and HCO3, are not great.
In our body we are basic at a pH of — so the buffer is operating at that pH, so it exists more as a —– rather than as an —— so it’s not that powerful because it doesn’t exist in equal amounts of acid and base
This is a limiting factor
In our body we are basic at a pH of 7.4 so the buffer is operating at that pH, so it exists more as a base rather than as an acid so it’s not that powerful because it doesn’t exist in equal amounts of acid and base
Phosphate buffers
The main elements of the phosphate buffer system are —- and —–.
The buffer system has a pk of —-.
The phosphate buffer is especially important in the —- fluids of the —-.
The phosphate buffer is especially important in the —— fluids of the ——-, for two reasons:
(1) phosphate usually becomes greatly ———- in the tubules, thereby ——- the buffering power of the phosphate system
(2) the tubular fluid usually has a —— pH than the extracellular fluid does, bringing the operating range of the buffer —— to the pK (6.8) of the system.
The main elements of the phosphate buffer system are H2PO4- and HPO4-.
The buffer system has a pk of 6.8.
The phosphate buffer is especially important in the tubular fluids of the kidney.
The phosphate buffer is especially important in the tubular fluids of the kidney, for two reasons:
(1) Phosphate usually becomes greatly concentrated in the tubules, thereby increasing the buffering power of the phosphate system
(2) The tubular fluid usually has a lower pH than the extracellular fluid does, bringing the operating range of the buffer closer to the pK (6.8) of the system.
Respiratory regulation of acid-base balance
Acts rapidly and keeps the — concentration from changing too much until the slowly responding —— can eliminate the imbalance
It is one to 2 times greater as the buffering power of all other chemical buffers. So 1 to 2 times as much acid and base can normally be buffered by this mechanism.
Acts rapidly and keeps the H+ concentration from changing too much until the slowly responding kidneys can eliminate the imbalance
Respiratory regulation of acid-base balance
increased alveolar ventilation,
- ——- removal of CO2 so
- ——– partial pressure of CO2, so ———- CO2 combining with water, ———- carbonic acid, ——— H+ concentration in the extracellular fluid and — back to normal
This is the —– line of defense, which controls extracellular fluid —– concentration by the lungs.
Changes in either ——– ventilation or the rate of —– formation by the tissues can change the extracellular fluid —–.
Respiratory regulation of acid-base balance
increased alveolar ventilation,
increased removal of CO2 so decreased partial pressure of CO2, so decreased CO2 combining with water, decreased carbonic acid, decreased H+ concentration in the extracellular fluid and pH back to normal
This is the second line of defense, which controls extracellular fluid CO2 concentration by the lungs.
Changes in either pulmonary ventilation or the rate of CO2 formation by the tissues can change the extracellular fluid PCO2.
Respiratory regulation of acid-base balance
increased alveolar ventilation,
- ——- removal of CO2 so
- ——– partial pressure of CO2, so ———- CO2 combining with water, ———- carbonic acid, ——— H+ concentration in the extracellular fluid and — back to normal
This is the —– line of defense, which controls extracellular fluid —– concentration by the lungs.
Changes in either ——– ventilation or the rate of —– formation by the tissues can change the extracellular fluid —–.
Respiratory regulation of acid-base balance
increased alveolar ventilation,
increased removal of CO2 so decreased partial pressure of CO2, so decreased CO2 combining with water, decreased carbonic acid, decreased H+ concentration in the extracellular fluid and pH back to normal
This is the second line of defense, which controls extracellular fluid CO2 concentration by the lungs.
Changes in either pulmonary ventilation or the rate of CO2 formation by the tissues can change the extracellular fluid PCO2.
Increase in ventilation ——- pH
Decrease in ventilation ——– pH
The normal rate of alveolar ventilation is —-. At this rate the change in pH of body fluids is —.
The alveolar ventilation rate doesn’t change much during changes in atrial blood pH from 7.4 to 7.2 because of the acting ——-.
Increase in ventilation increases pH
Decrease in ventilation decreases pH
The normal rate of alveolar ventilation is 1. At this rate the change in pH of body fluids is 0.
The alveolar ventilation rate doesn’t change much during changes in atrial blood pH from 7.4 to 7.2 because of the acting buffers.
How does the kidney regulate pH?
Secretion of H+
Reabsorption of filtered HCO3-
Production of new HCO3-
kidney regulation of pH
Secretion of H+
There are ——- ——- (3 Na out, 2K in), there is always a drive for sodium to move —- the cell
There is a filtrate in the tubular lumen, there is sodium and bicarbonates (phosphate buffers) filtering in.
The sodium is taken — the cell and a — ion is exchanged into the lumen via Na/H+ exchangers, which then goes onto combine with the ————- to form H2CO3, which then dissociates into —— and ——-.
The —— then goes into the cell and combines with —— to produce H2CO3 which dissociates into ——- and —-, with the ——- moving out of the cell and into the blood
It’s complicated because the kidney doesn’t have a system that can actively reabsorb bicarbonates
There are Na/K ATPases (3 Na out, 2K in), there is always a drive for sodium to move into the cell
There is a filtrate in the tubular lumen, there is sodium and bicarbonates (phosphate buffers) filtering in.
The sodium is taken into the cell and a H+ ion is exchanged into the lumen via Na/H+ exchangers, which then goes onto combine with the bicarbonate to form H2CO3, which then dissociates into CO2 and H20.
The CO2 then goes into the cell and combines with H20 to produce H2CO3 which dissociates into HCO3- and H+, with the HCO3- moving out of the cell and into the blood
kidney regulation of pH
Active secretion of H+
When there is a lot of acid in the body it actively secretes __ ions
This is done via —-exchangers, which are secondary active transporters turning ATP to ADP when removing the —— into the lumen
The bicarbonate goes back into the cell
When there is a lot of acid in the body it actively secretes H+ ions
This is done via H/Cl exchangers, which are secondary active transporters turning ATP to ADP when removing the H+ into the lumen
The bicarbonate goes back into the cell
kidney regulation of pH
Addition of new HCO3-
There are ——— ——-(3 Na out, 2K in), there is always a drive for sodium to move —- the cell
There is a filtrate in the tubular lumen, there is phosphate buffers filtering in, the —- is taken into the cell and a — ion is exchanged into the lumen (sodium hydrogen exchangers), which then goes onto combine with ——- to form NaH2PO4, which is excreted out of the body.
The —- in the blood goes into the cell and combines with —— to produce H2CO3 which dissociates into —- and —-, with the HCO3- moving out of the cell and into the blood.
There are Na/K ATPases (3 Na out, 2K in), there is always a drive for sodium to move into the cell
There is a filtrate in the tubular lumen, there is phosphate buffers filtering in, the sodium is taken into the cell and a H+ ion is exchanged into the lumen (sodium hydrogen exchangers), which then goes onto combine with NaHPO4- to form NaH2PO4, which is excreted out of the body.
The CO2 in the blood goes into the cell and combines with water to produce H2CO3 which dissociates into HCO3- and H+, with the HCO3- moving out of the cell and into the blood.
kidney regulation of pH
Addition of new HCO3-
Glutamine dissociates into —- and —– ions which get exchanged into the lumen with sodium ions.
The —- and — gets lost in the urine
The body gains – bicarbonate ions
Glutamine dissociates into HCO3- and NH4+ ions which get exchanged into the lumen with sodium ions.
The NH4+ and Cl gets lost in the urine
The body gains 2 bicarbonate ions
Respiratory acidosis (pCO2)
The pH is ——– 7.4
There is ——- H+
There is ——– PCO2
The pH is below 7.4
There is increased H+
There is increased PCO2
Respiratory alkalosis (PCO2)
The pH is ——- 7.4.
There is ——- H+.
There is ——- PO2.
The pH is above 7.4
There is decreased H+
There is decreased PCO2
Metabolic acidosis (HCO3-)
The pH is ——- 7.4
There is —– H+.
There is ——– HCO3-
The pH is below 7.4
There is increased H+.
There is decreased HCO3-
Metabolic alkalosis (HCO3-)
The pH is ——- 7.4
There is —– H+.
There is ——– HCO3-
The pH is above 7.4
There is decreased H+.
There is increased HCO3-
