205 L4

Question 1

Molecules containing hydrogen atoms that can release hydrogen ions in solutions are referred to as —-.

Answer 1

Acids

Question 2

A —- is an ion or a molecule that can accept an H+

Answer 2

Base

Question 3

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+.

Answer 3

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+.

Question 4

What is the normal pH of atrial blood?

Answer 4

7.4

Question 5

Is the pH of venous blood and interstitial fluid above the normal atrial blood pH or below?

Answer 5

Below because of the extra amounts of carbon dioxide released from the tissues to form H2CO3 in these fluids.

Question 6

Is the pH of venous blood and interstitial fluid above the normal atrial blood pH or below?

Answer 6

Below because of the extra amounts of carbon dioxide released from the tissues to form H2CO3 in these fluids.

Question 7

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+)

Answer 7

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+)

Question 8

Name the mechanisms of pH control from immediate reaction to slow reaction.

Answer 8

Acid-Base buffer system

Respiratory center

Kidneys

Question 9

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.

Answer 9

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.

Question 10

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.

Answer 10

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.

Question 11

The respiratory center

Regulates the removal of —— and therefore ——–, from the ——— fluid.

This is the ——- line of defence.

Answer 11

Regulates the removal of CO2 and therefore H2CO3, from the extracellular fluid.

This is the second line of defence.

Question 12

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.

Answer 12

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

Question 13

The more ——– ions the greater the pH.

Answer 13

The more bicarbonate ions (HCO3-) the greater the pH (pH is directly proportional to HCO3-)

Question 14

Higher ——- the lower the pH

Answer 14

Higher Pco2 the lower the pH (pH is inversely proportional to Pco2)

Question 15

Name the buffer systems.

Answer 15

Bicarbonate buffers
phosphate buffers
Proteins

Question 16

———- buffers are ubiquitous, act fast to sort out pH but are not strong.

Answer 16

Bicarbonate buffers

Question 17

——– buffers are limited to the kidney tubules but are strong buffers

Answer 17

Phosphate buffers

Question 18

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.

Answer 18

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.

Question 19

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

Answer 19

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

Question 20

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.

Answer 20

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.

Question 21

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.

Answer 21

Acts rapidly and keeps the H+ concentration from changing too much until the slowly responding kidneys can eliminate the imbalance

Question 22

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 —–.

Answer 22

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.

Question 23

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 —–.

Answer 23

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.

Question 24

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 ——-.

Answer 24

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.

Question 25

How does the kidney regulate pH?

Answer 25

Secretion of H+

Reabsorption of filtered HCO3-

Production of new HCO3-

Question 26

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

Answer 26

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

Question 27

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

Answer 27

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

Question 28

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.

Answer 28

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.

Question 29

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

Answer 29

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

Question 30

Respiratory acidosis (pCO2)

The pH is ——– 7.4

There is ——- H+

There is ——– PCO2

Answer 30

The pH is below 7.4

There is increased H+

There is increased PCO2

Question 31

Respiratory alkalosis (PCO2)

The pH is ——- 7.4.

There is ——- H+.

There is ——- PO2.

Answer 31

The pH is above 7.4

There is decreased H+

There is decreased PCO2

Question 32

Metabolic acidosis (HCO3-)

The pH is ——- 7.4

There is —– H+.

There is ——– HCO3-

Answer 32

The pH is below 7.4

There is increased H+.

There is decreased HCO3-

Question 33

Metabolic alkalosis (HCO3-)

The pH is ——- 7.4

There is —– H+.

There is ——– HCO3-

Answer 33

The pH is above 7.4

There is decreased H+.

There is increased HCO3-