Acid-Base

Question 1

Because of its small radius, … is more reactive than other cations in body fluids.

Answer 1

H+

Question 2

[H+] in plasma is maintained between …

Answer 2

38-42 nEq/L

Question 3

What are the 3 sources of H+ input into the biological system?

Answer 3

metabolic products (including CO2), dietary intake of acids, and loss of alkali in the GI tract

Question 4

Metabolism produces a large amount of …, which must be excreted in the expired air.

Answer 4

volatile acid

Question 5

What two characteristics of CO2 make it a volatile acid?

Answer 5

because it can be removed by ventilation, but has the potential to produce H+ when hydrated

Question 6

How many moles of volatile acid per day is produced by metabolic activity and removed by ventilation?

Answer 6

15-20 moles

Question 7

Are volatile acids normally a source of H+?

Answer 7

no

Question 8

What are 2 sources of a fixed or nonvolatile source of acid?

Answer 8

H+ ingested with foods or in the form of medications

Question 9

What is the concentration of nonvolatile acid per day?

Answer 9

20 mEq/per day

Question 10

These ingested H+ cannot be removed from the system by ventilation, thus are …

Answer 10

nonvolatile

Question 11

Incomplete … during excessive metabolic activity, in the absence of insulin, or during inadequate oxygenation can lead to production of nonvolatile acids like lactic, pyretic, and B-hydroxybutyric acids

Answer 11

glucose and fat metabolism

Question 12

The net acid/base input for a typical American (Western) diet is usually …

Answer 12

acidic

Question 13

The loss of base in the form of …., in the stool leaves a net H+ excess in the body

Answer 13

HCO3-

Question 14

H+ is excreted into the urine as titratable (nonvolatile) acids such as … and as …, part of a buffer system which is unique to the kidneys.

Answer 14

phosphates (HPO4-2/H2PO4-) and as ammonium ion

Question 15

It is not possible to eliminate the entire daily H+ load in the form of free H+ because urine can only reach pH of 4.5. Therefore, we must employ … in order to remove the normal acid load from the body.

Answer 15

chemical buffers of H+

Question 16

What diet results in acid production > HCO3- production?

Answer 16

meat-containing diets

Question 17

What diet results in a net production of alkali in the form of HCO3-, and therefore a net alkaline load and renal excretion of HCO3-?

Answer 17

vegetarian

Question 18

Hb is an important … buffer.

Answer 18

intracellular

Question 19

The respiratory system will respond to an acid load. H+ will stimulate … to increase ventilation

Answer 19

peripheral chemoreceptors (carotid bodies)

Question 20

Is the respiratory control response slow or fast?

Answer 20

fast, occurs within less than a minute, but can be sustained for long periods

Question 21

The kidneys must excrete an amount of acid equal to the total ….

Answer 21

nonvolatile acid production (which includes normal loss of HCO3- in stool)

Question 22

The kidneys must replace the…, and prevent the loss of …

Answer 22

HCO3- lost in buffering reactions; filtered HCO3- in the urine

Question 23

Is the renal response fast or slow?

Answer 23

slow and may take several days for the full response to an acid-base disturbance to be evident

Question 24

What does the renal system excrete acids as?

Answer 24

H2PO4- and NH4+

Question 25

What does the Isohydric Principle state?

Answer 25

A change in one buffer pair causes parallel changes in other buffer systems; therefore we can base our analysis on the bicarb system alone.

Question 26

Since H2CO3 represents the pivot point in the bicarb buffering system adding acid forces the reaction to ...

Answer 26

CO2 elimination

Question 27

Since H2CO3 represents the pivot point in the bicarb buffering system adding alkali (-OH) increases ..., which can be eliminated by...

Answer 27

HCO3- (-OH combines with CO2), which can be eliminated by the kidneys or by buffering reactions

Question 28

In the bicarb buffering system the supply of what is virtually inexhaustible due to metabolic production of CO2?

Answer 28

H2CO3

Question 29

The Henderson-Hasselbach equation is used to calculate ...

Answer 29

how changes in CO2 and HCO3- affect pH

Question 30

The cellular hydration mechanism produces a ... that moves across the apical membrane and a ... that moves across the basolateral membrane.

Answer 30

H+; HCO3-

Question 31

What is the predominant pathway within the proximal RTC for H+ secretion into tubular fluid?

Answer 31

Na+-H+ antiport = NHE3

Question 32

Where does the energy used to drive NHE3 come from?

Answer 32

Na+-K+ active exchange pump on the basolateral membrane

Question 33

What is present in the apical membrane of both distal and proximal RTCs that make H+ secretion primary active transport?

Answer 33

H+-ATPase

Question 34

in the distal RTCs what is the other primary active transport mechanism of H+ secretion?

Answer 34

apical membrane H+-K+ ATPase

Question 35

The preservation of filtered bicarb is achieved by proximal and distal RTC ...

Answer 35

H+ secretion