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Ella Notes for PHGY 216 > Acid-Base Balance > Flashcards

Acid-Base Balance Flashcards

1
Q

Define acids and bases and describe why pH is so tightly regulated by the body

A
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2
Q

Describe the physiological buffer systems and explain their primary functions

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3
Q

Explain how the lungs and kidneys work together to maintain normal pH

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4
Q

Describe the major types of acid-base imbalances and explain how each of them ca be compensated for

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5
Q

Describe the difference between an acid and a base and explain how pH is calculated

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6
Q

Define acidosis and alkalosis and describe their broader impacts on the body

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7
Q

Describe acids

A

Dissociates into an anion and H+
The more H+ dissociate = stronger acid
HCl is a strong acid

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8
Q

describe bases

A

Will bind free H+ and remove it
The stronger the base, the easier it binds H+

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9
Q

describe acid base balance

A

Acid-base balance is the regulation of H+ ions in the body fluids

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10
Q

describe pH designation

A

pH was developed to be able to express the amount of H+ in a solution in a more convenient manner
The higher the H+ = the lower the pH (lower pH=acidic)
Each pH unit represents a 10 fold change
Pure water is 7.0 “neutral”
2.4-6.4 = 10^4

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11
Q

describe acidosis and alkalosis in the body

A

pH is highly regulated
Normal arterial blood is 7.45 and venous blood is 7.35
7.4 is average normal body pH
Acidosis is when blood pH falls below 7.35
Alkalosis in blood is when blood pH falls above 7.45
6.8 or 8.0 blood pH = death

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12
Q

describe the effects of large pH changes

A

Nerve and muscle cells are affected (Acidosis suppresses CNS=death by coma) (Alkalosis is overexcitability of CNS and PNS=death by spasms)
pH changes slow or speed up enzymatic reactions
Changes in H+ can also affect K+ in fluids (increasing plasma K) exciting cells and making them more excitable

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13
Q

where is H+ produced in the body (2 sources)

A
  1. Carbonic Acid formation
    (metabolic by-products of cellular respirations are CO2 and H20, and in the presence of carbonic anhydrase, they are converted into carbonic acid (H2CO3), which then dissociates into bicarbonate and H+,
    CO2 + H2O <-> H2CO3 <-> + H
    No net increase or decrease of H
  2. Inorganic Acids produced from nutrient breakdown
    Sulphur and phosphorus-strong acids that dissociate
    Organic Acids from Intermediary Metabolism
    Glucose in working muscle goes to lactate in muscle which are weak acids that contribute to H
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14
Q

Describe how a buffer system operates, and identify and locate the major buffer systems of the body

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15
Q

Define the Henderson-Hassle Balch equation, especially with regard to its implications of how CO2 and HCO3 ion concentrations interact to maintain acid-base homeostasis in the body

A
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16
Q

what are the 4 chemical buffer systems

A

The H2CO4 HCO3 buffer system
The protein buffer system
The haemoglobin buffer system
The phosphate buffer system

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17
Q

describe The H2CO3:HCO3 Buffer Pair

A

The carbonic acid/bicarbonate buffer pair
When a base is added to a solution with this buffer, the base will bind to free H+, which makes more H+ dissociate
The opposite is true when an acid is added to the solution, the reaction will go backwards so less H+ dissociate
Most important for buffering pH changes
A buffer cannot buffer itself though
Both H2CO3 and HCO3 are present in high quantities in the ECF, meaning this system has a high capacity for buffering pH changes
Both H2CO3 and HCO3 are regulated (kidneys do bicarbonate and resp system does H2CO3 by regulating (CO2)

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18
Q

describe The H2CO3:HCO3 Buffer Pair during exercise

A

Intense exercise=lactic acid = higher concentration oh H+ in the body, which will bind to HCO3 and drive the reaction to the left (this moves H so it cannot increase the acidity)

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19
Q

describe The H2CO3:HCO3 Buffer Pair during vomiting

A

Opposite happens, H2CO3 dissociates to a release of H+ and prevents ECF from being too basic

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20
Q

describe the The Henderson-Hasselbalch Equation

A

Relationship between H+ and a buffer system pair (calculates the pH around which buffer pair works
HCO3 to CO2 ratio is 20:1

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21
Q

describe The Protein Buffer System

A

Amino acids are acidic and can give up H+ easily
If pH rises, amino acids release H+
If pH falls, amino acids absorb H+

22
Q

describe The Haemoglobin Buffer System

A

Co2 in plasma, as CO2 leaves the tissues and enters the blood, most of it forms H2CO3 in the RBCs, which helps form the carbonic anhydrase
HCO3 in Plasma., some of H2CO3 will immediately dissociate into HCO3 and H
O2 in plasma, most H will bind to haemoglobin and no longer make body fluids acidic (frees up the oxygen bound haemoglobin to be released to tissues)

23
Q

describe The Phosphate Buffer System

A

Acid phosphate salt that can donate H+ when H+ falls or accept an H+ when H concentration is increased
Acid phosphate salt level is low in ECF so it does not play a major role
Buffers the pH of the urine
(as well look at the eqtn on Ellas notes)

24
Q

what is the first line of defence

A

These chemical reactions are the first line of defence
They occur in fractions of a second
Limited capacity to absorb H+

25
Q

Describe the mechanism and location of the reabsorption of bicarbonate ion

A
26
Q

Describe how urinary phosphate and ammonia help the body secrete excess acid

A
27
Q

The Respiratory System and [H+]

A

Alters pulmonary ventilation to increase or decrease the removal of CO2
Arterial H+ is the primary determinant of resp activity
Unbuffered solution (Arterial H+ increases from non-resp sources), the resp centre in the brain stem stimulates to increase pulmonary ventilation (removing CO2=less HCO3 and H)
Buffered solution (arterial H decreases, pulmonary ventilation is reduced, decreases exhalation of CO2, allowing it to accumulate in the blood)

28
Q

The Kidneys and Acid-Base Balance

A

Kidneys remove sulphuric, phosphoric, and lactic acid
Can also remove some extra H+ produced by carbonic acid
How?
The excretion oh H+
The excretion/reabsorption of HCO3
The secretion of ammonia
Renal H Secretion
pH is acidic around 6.0 because of H+ secretions
Co2 enters tubule cells
Within the cells, CO2 and H20, under the influence of carbonic anhydrase, they form H2Co3, which becomes bicarbonate and H
An energy dependent carrier on the luminal membrane will then transport H into the tubular fluid
Rate control of H Secretion
H+ secretion is related to acid-base status of ECF
H+ is greater than normal, the tubular cells increase H secretion
When plasma CO2 rises, more H is secreted

29
Q

Reabsorption of Filtered HCO3

A

The kidneys regulate plasma HCO3 in two ways; reabsorption of HCO3 back into plasma, and addition of new HCO3 to the plasma
HCO3 in the tubular fluid combines with secreted H to form H2CO3, which then break down into HCO3 and CO2, both can cross the luminal membrane
Once inside a tubular cell, carbonic anhydrase converts CO2 and H20 back into H2CO3, which freely dissociates into HCO3 and H
HCO3 can cross the basolateral membrane so it leaves the cell and H is again secreted

30
Q

Addition of “New” HCO3 to the Plasma

A

CO2 from the plasma and tubular cell, along with hydroxyl radical from the dissociation of H20, is converted to HCO3 where it is transported across the basolateral membrane into the plasma
H is released from the dissociation of water and this H is then secreted into the tubular lumen, where it combines with urinary buffers, like basic phosphate and then excreted from the body

31
Q

Urinary Buffers

A

The body produces an incredible excess of H that it must be excreted in the urine
THE TUBULAR CELLS CAN SECRETE UNTIL ITS PH IS 4.5, THEN IT CANNOT SECRETE MORE
URINARY BUFFER SYSTEMS CAN REMOVE THE FREE H+
Phosphate
Limited buffering capacity
Ammonia
When the phosphate buffer system is overwhelmed (acidic conditions), the tubular cells secrete ammonia (NH3), which reacts with H to form ammonium (NH4), thereby removing an H from the body.

32
Q

Describe the differences in respiratory and metabolic acid-base imbalances

A
33
Q

Describe and explain the concept of anion gap

A
34
Q

Describe the respiratory and metabolic acidosis

A
35
Q

acidosis is below

A

7.4

36
Q

alkalosis is above

A

7.4

37
Q

acid base disorders (4)

A

Respiratory acidosis
Metabolic acidosis
Respiratory alkalosis
Metabolic alkalosis

38
Q

what is respiratory acidosis

A

Build up of CO2
Hypoventilation and less than normal CO2 is removed
Uncompensated=H leads to acidosis
Compensated=chemical buffers take up extra H and kidneys secrete more H
Resp system cannot compensate for this

39
Q

what is respiratory alkalosis

A

Increase in ventilation that drops CO2 plasma levels
Fear, anxiety, and severe infections
Uncompensated=increased pH
Compensated=Chemical buffer system release H+ and the resp system decreases ventilation

40
Q

what is metabolic acidosis

A

Decrease in HCO3 (normal CO2)
Happens from excessive loss of HCO3 or non-carbonic acid build up
We measure anion gap to determine the cause

41
Q

what is the anion gap

A

Low Anion Gap= loss of plasma albumin (haemorrhage) less than 8
Normal Anion Gap= loss of HCO3 (caused by diarrhea) 8-16
High Anion Gap (increase in unmeasured anions) 16

42
Q

what are causes of metabolic acidosis

A

Severe diarrhea (HCO3 drop)
Diabetes Mellitus (increase in keto acids)
Strenuous exercise (lactic acid is produced)
Uraemic Acidosis (renal failure)

43
Q

what are compensations of metabolic acidosis

A

Decrease in HCO3 and a normal CO2
Buffers (except uraemic acidosis) take up extra H+, lungs blow off extra CO2, and conserving HCO3
Resp system can only partially compensate

44
Q

what is metabolic alkalosis

A

Reduced H caused by a decrease in carbonic acids, increase in HCO3
Vomiting (loss of stomach H)
Alkaline Drug Ingestion (high amounts of HCO3 and this raises HCO3 and decreases plasma H

45
Q

uncompensated metabolic alkalosis

A

excess of HCO3

46
Q

Compensated metabolic alkalosis

A

Ventilation reduces to raise plasma CO2
Over several days, kidneys decrease H secretion

47
Q

define acids and bases + describe why pH is so tightly regulated by the body

A
48
Q

describe the physiological buffer systems and explain their primary functions

A
49
Q

explain how the lungs and kidneys work together to maintain normal pH

A
50
Q

describe the major types of acid-base imbalances and explain how each of them can be compensated for

A

Ella Notes for PHGY 216 (3 decks)

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