Basics of acid base balance

Question 1

Why is it important to regulate blood pH?

Answer 1

Many chemical reactions are pH sensitive

Excess protons will bind to proteins and change their charge

Question 2

What will excess protons do to proteins?

Answer 2

Bind to them and change their charge

Question 3

Body reactions produce enough acid to make a pH of what?

Answer 3

1

Question 4

What two components make a good buffer?

Answer 4

Weak acid and weak conjugate base

Question 5

What are the two types of buffer in our bodies?

Answer 5

Intracellular

Extracellular

Question 6

What are examples of intracellular buffers?

Answer 6

Proteins

Phosphates

Haemoglobin

Question 7

What is the main buffer of RBCs?

Answer 7

Haemoglobin

Question 8

What are examples of extracellular buffers?

Answer 8

Bicarbonate ions

Phosphate ions

Proteins

Question 9

What are the two types of acids you can find in the body?

Answer 9

Volatile

Non-volatile

Question 10

What are volatile acids?

Answer 10

Acids you can get rid off

Question 11

What is the main buffer in the blood?

Answer 11

Bicarbonate ions

Question 12

How is bicarbonate made?

Answer 12

When the unstable intermediate carbonic acid, that is made from the reaction between carbon dioxide and water, breaks down

Question 13

What are non-volatile acids?

Answer 13

Acids you can’t get rid of (buffer)

Question 14

What is an example of a non-volatile acid?

Answer 14

Sulphate derived from the metabolism of sulphur-containing amino acids

Question 15

How are non-volatile acids removed from the body?

Answer 15

Via the kidneys

Question 16

What gas is central to the control of pH?

Answer 16

Carbon dioxide

Question 17

Protons determine the pH of blood

TRUE or FALSE

Answer 17

TRUE

Question 18

How is carbon dioxide controlled in the body?

Answer 18

Negative feedback loop

Chemoreceptors sense the proton concentration of the blood

Increase in ventilation counterracts the increase in pH

Question 19

What is the result of increasing breathin rate on the pH of the blood?

Answer 19

Increasing breathing rate

Reduces carbon dioxide concentration

Less carbonic acid is produced

Less protons are produced

Reversible reaction is pushed to form more carbon dioxide

Question 20

Why do we need protein buffers?

Answer 20

Hydrogen ions are transported across membranes

Question 21

What is the composition of RBC cell membranes?

Answer 21

50% proteins

33% Hb

Question 22

What parts of the proteins act as buffers?

Answer 22

Carboyl group

Amino groups

Question 23

What is an important amino acid found in Haemoglobin?

Answer 23

Histidine

Hb = 8% histidine

Question 24

Why is histidine an important component of Hb?

Answer 24

Histidine’s pKa (buffering capacity) = 6

This means it works best at pH 6

Amino acid with pKa closest to the physiological pH

Question 25

How does Hb buffer?

Answer 25

Somatic cells release carbon dioxide into the extracellular fluid Carbon dioxide enters RBC and forms carbonic acid Carbonic acid dissociates releasing protons Protons are charged and so cannot leave the cell Oxyhaemoglobin exchanges oxygen for a proton Oxygen is released and enters somatic cells

Question 26

Does chemical buffering work in the long term?

Answer 26

No Molecules get oversaturated and don't work anymore

Question 27

What is a technique used by the body to spread the effects of hydrogen ion changes?

Answer 27

Buffer proteins are found spread throughout the body

Question 28

What causes disturbances of pH?

Answer 28

Respiratory acidosis Respiratory alkalosis Metabolic acidosis Metabolic alkalosis

Question 29

What is respiratory acidosis?

Answer 29

Insufficient removal of carbon dioxide Due to inadequate breathing or high carbon dioxide concentration in the air Rise in CO2 in plasma = more carbonic acid produced = more protons

Question 30

What is respiratory alkalosis?

Answer 30

Excess removal of carbon dioxide Hyperventilation or high altitude Fall in plasma carbon dioxide = less carbonic acid produced = less protons

Question 31

What is metabolic acidosis?

Answer 31

Excess production of non-volatile acids Due to voluntary ingestion of methanol Or loss of base from the gut during diarrhea Fall in plasma pH and increase in bicarbonate concentration

Question 32

What is metabolic alkalosis?

Answer 32

Excess non-volatile bases Due to vomiting

Question 33

What causes respiratory acidosis?

Answer 33

Decreased ventilation Increased carbon dioxide concentration in the air

Question 34

What causes respiratory alkalosis?

Answer 34

Increased ventilation High altitude

Question 35

What causes metabolic acidosis?

Answer 35

Loss of base during diarrhea Consumption of methanol

Question 36

What causes metabolic alkalosis?

Answer 36

Vomiting

Question 37

How does consumption of methanol lead to metabolic acidosis?

Answer 37

Methanoic acid results in increased lactic acid Since the cytochrome in mitochondria is inhibited