Acids & Bases

Question 1

What is an acid?

Answer 1

Any molecule that will release H+ when put into solution.

Question 2

What is a base?

Answer 2

Any molecule that will accept H+.

Question 3

The more free H+ there are in solution, the more _____ the solution and the ______ the pH.

Answer 3

acidic, lower.

Question 4

Below 7…

Answer 4

Acidic

Question 5

Above 7…

Answer 5

Basic

Question 6

Equal to 7…

Answer 6

Neutral

Question 7

What is the pH of body fluids?

Answer 7

7.35-7.45

Question 8

Arterial blood pH?

Answer 8

7.45

Question 9

Venous blood pH?

Answer 9

7.35

Question 10

Define acidosis.

Answer 10

Term used to describe body fluids when pH is below 7.4

Question 11

Define alkalosis.

Answer 11

Occurs when pH is above 7.4

Question 12

Describe the source of acid in the body.

Answer 12

1. When cells in the body make energy, they produce CO2 as a byproduct, which can (with the help of carbonic anhydrase) combine with water is RBC’s to produce carbonic acid.
2. Carbonic acid will dissociate into free H+ and bicarbonate ions.
3. As a result, there is generally no net increase in free H+ in the plasma.

Question 13

Why is carbonic acid known as a volatile acid?

Answer 13

Because the carbonic acid reforms into CO2, which is then removed at the lungs.

Question 14

What are examples of non-volatile acids?

Answer 14

Hydrochloric, sulphuric and lactic acid.

Question 15

True or false; non-volatile acids can be removed by the lungs.

Answer 15

FALSE: Non-volatile acids are a significant source of free H+ and are constantly produced throughout the body.

Question 16

Define buffer.

Answer 16

Any molecule that can reversibly bind/release free H+. Buffers bind to free H+, thereby reducing the amount of free H+ in solution.

Question 17

True of false; buffers prevent the pH from changing.

Answer 17

FALSE: Buffers cannot prevent the pH from changing, they only help to minimize any pH change until the free H+ can be removes via the kidneys or lungs.

Question 18

List the intracellular buffers.

Answer 18

Phosphates and intracellular proteins (hemoglobin).

Question 19

Can free H+ bind to intra or extracellular fluid?

Answer 19

Both

Question 20

What is the most powerful extracellular buffer?

Answer 20

Bicarbonate ion

Question 21

What can hemoglobin bind with?

Answer 21

Hb inside RBC’s can reversibly bind with free H+ to help stabilize the acidity. Hb can also bind with CO2 to reduce potential acidity should CO2 combine with H2O to form carbonic acid.

Question 22

What detects CO2 gas?

Answer 22

Central and peripheral chemoreceptors.

Question 23

What happens when CO2 levels increase?

Answer 23

Central and peripheral receptors detect change and cause an increase in ventilation. Increased ventilation causes more CO2 to be removed from the lungs, which will then return blood CO2 back to normal.

Question 24

How do the kidneys maintain a constant pH?

Answer 24

1. Excrete H+ that comes from non-volatile acids.
2. Attempt to reabsorb all bicarbonate ions that are filtered at the glomerulus.
3. Create new bicarbonate ions which then get absorbed into circulation.

Question 25

What % of bicarbonate that is filtered in the glomerulus is absorbed and where in the nephron is it absorbed?

Answer 25

90%, in the proximal tubule.

Question 26

Where is H+ excreted in the nephron and by what mechanism?

Answer 26

Proximal tubule by the Na+/H+ exchanger | Late distal tubule by the H+/ATP pump

Question 27

Explain the reabsorption of bicarbonate ions/secretion of H+.

Answer 27

1. Bicarbonate ions (filtered freely at the glomerulus into the filtrate) cannot directly be reabsorbed by tubule cells. 2. Bicarbonate ions must be converted into CO2, which is then reabsorbed. 3. Once in the tubule cells, CO2 combines with H2O, and with the help of carbonic anhydrase, will produce bicarbonate and H+. 4. Bicarbonate ions leave tubule cells by simple diffusion and reabsorbed back into circulation. 5. Remaining H+ in the cell are secreted into the lumen by Na+/H+ exchanger. 6. For every bicarbonate ion reabsorbed, there must be one H+ secreted.

Question 28

When can acidosis occur?

Answer 28

When there is too much H+ (acid) OR too little bicarbonate ion (most common base in the body).

Question 29

When can alkalosis occur?

Answer 29

When there is too much bicarbonate and too little H+.

Question 30

What is respiratory acidosis caused by and when can it occur?

Answer 30

Caused by decreased ventilation and increased partial pressure of CO2. This can occur if the respiratory centre in the brain stem is damaged r from lung damage resulting in decreased ability to remove CO2 from the blood.

Question 31

How can respiratory acidosis be counteracted?

Answer 31

By buffers in the blood and excretion of excess H+ by the kidneys.

Question 32

What is respiratory alkalosis caused by and when can it occur?

Answer 32

Caused by an increase in ventilation and decreased partial pressure of CO2. Although infrequent, can be caused by stress or emotionally induces hyperventilation. Hyperventilation will increase removal of CO2 from the blood, causing the decrease in PCO2. High altitudes can also result in respiratory alkalosis when low O2 levels cause low PO2 levels in the blood that stimulates hyperventilation.

Question 33

How can respiratory alkalosis be counteracted?

Answer 33

The excretion of bicarbonate ions from the kidneys.

Question 34

What is metabolic acidosis caused by and when can it occur?

Answer 34

Caused by a number of factors that result in a decrease in extracellular bicarbonate ions. Metabolic acidosis DOES NOT involve increased CO2 in the blood. Causes include... 1. Kidney failure resulting in the inability to excrete acids in urine/inability to reabsorb bicarbonate from the filtrate. 2. Formation of excess metabolic acids in the body. 3. Ingestion of acids (most common = aspirin/methyl alcohol). 4. Loss of bicarbonate in diarrhea

Question 35

What is metabolic alkalosis caused by and when can it occur?

Answer 35

Caused by either buildup of bicarbonate ions or the loss of H+ from the body. Most common cause is the loss of HCl from the stomach from vomiting, or the ingestion of alkaline drugs (sodium bicarbonate for treating ulcers).

Question 36

What are the three ways the body deals with the accumulation of acids?

Answer 36

1. Buffers 2. Kidneys 3. Respiratory System

Question 37

How do buffers deal with the accumulation of acids?

Answer 37

Reversibly bind with free H+ until they can be removed, don't dramatically affect the pH of blood.

Question 38

How does the respiratory system deal with the accumulation of acids?

Answer 38

Can detect levels of CO2 (a potential source of acid) and remove it from the body.

Question 39

How do they kidneys deal with the accumulation of acids?

Answer 39

Remove free H+ from nonvolatile acids.