H+J. Lecture 28+29 Regulation of acid-base balance Flashcards
(147 cards)
1
Q
do acids accept or yield protons?
A
yield
2
Q
do bases accept or yield protons?
A
accept
3
Q
do strong acids/bases dissociate more or less in solution compared to weak acids/bases?
A
dissociate more
4
Q
do strong or weak acids liberate more protons?
A
strong
5
Q
do strong or weak acids buffer more protons?
A
weak
6
Q
what is the equation for the dissociation constant?
A
(proton conc x conjugate base conc)/ (conc of undissociated acid)
7
Q
what is the equation for pH?
A
-log10[H+]
8
Q
what happens to [H+] as pH goes down/more acidic?
A
it increases
9
Q
what is the [H+] in ECF?
A
around 4 x 10-8 M
10
Q
what is the pH of arterial blood?
A
around 7.45
11
Q
what is the pH of venous blood?
A
around 7.35
12
Q
what is the pH range compatible with life?
A
6.8-8.0
13
Q
what happens outside the pH range of 6.8-8.0?
A
death
14
Q
what is pH less than 7.35 called?
A
acidosis
15
Q
what is pH more than 7.45 called?
A
alkalosis
16
Q
what 3 things can small changed in pH affect?
A
Nerve excitability
Enzyme activity
K+ homeostasis
17
Q
what affects does acidosis have on CNS activity?
A
decreases it
18
Q
what can acidosis lead to?
A
disorientation, coma, death
19
Q
what affects does alkalosis have on CNS activity?
A
increases it
20
Q
what can alkalosis lead to?
A
pins/needles, muscle twitch, death
21
Q
what are enzymes?
A
proteins that are made from AAs
22
Q
what are AA R-groups?
A
titratable side-chains
23
Q
why is R-group charge vital?
A
to correct folding
24
Q
why is the 3D shape of enzymes vital?
A
for functioning
25
are proton handling and K+ secretion linked?
yes
26
what effect does acidosis have on secretion of H+?
increases it
27
what does an increase in secretion of H+ result in?
decrease secretion of K+
28
what does a decrease secretion of K+ lead to?
hyperkalaemia
29
what does hyperkalaemia cause?
depolarisation of excitable cells
30
what are the 2 sources of acids and bases?
food and metabolism
31
how are proteins a source of acids?
contain phosphorus and sulphur, converted to phosphoric and sulphuric acid (strong acids)
32
what does fruit digestion yield?
release of bases
33
what is released from fat metabolism?
fatty acids
34
what type of acids are fatty acids?
Weak acids, yield protons
35
what is produced from anaerobic glycolysis?
lactic acids
36
what type of acid lactic acid?
Weak acid, yields protons
37
what is CO2 from respiring cells hydrated to form?
carbonic acid
38
is carbonic acid a strong or weak acid?
weak
39
what is the formation of carbonic acid catalysed by?
carbonic anhydrase
40
is the formation of carbonic acid reversible?
yes, at the lungs
41
what produces vast quantities of carbonic acid?
respiring cells
42
what are the 3 mechanisms of maintaining acid-base balance?
Blood buffers
Respiratory compensation
Renal compensation
43
how long do blood buffers take to work?
seconds
44
how long does respiratory compensation take to work?
minutes
45
how long does renal compensation take to work?
hours to days
46
what is a buffer?
weak acid or base
47
can buffers absorb protons?
yes
48
is blood buffering effective?
yes, very effective
49
what is the main blood buffer?
bicarbonate
50
is H2CO3 difficult to measure?
yes, very difficult to measure
51
what does the relationship of CO2 and H2CO3 in solution depends on?
partial pressure (Pco2) and its solubility
52
what is the equations for pK?
-log10K
53
what is the Henderson-Hasselbalch equation?
pH = pK + log10([HCO3-] /alphaPco2)
54
what does blood pH depend on?
HCO3- and CO2 concentration
55
what can be altered to regulate pH?
CO2
| HCO3-
56
how is CO2 regulated?
by the lungs
57
how is HCO3- regulated?
by the kidneys
58
how can conditions be diagnosed clinically?
by measuring H-H equation parameters
59
what effect does respiratory acidosis have on CO2?
increases it
60
what affect does increased CO2 have on bicarbonate?
increases it
61
what affect does increased bicarbonate have on H+?
increases it
62
what affect does increased H+ have on pH?
decreases it
63
what effect does respiratory alkalosis have on CO2?
decreases it
64
what affect does decreased CO2 have on bicarbonate?
decreases it
65
what affect does decreased bicarbonate have on H+?
decreases it
66
what affect does decreased H+ have on pH?
increases it
67
what affect does metabolic acidosis have on pH and bicarbonate?
add acid, decreases them
68
what affect does metabolic alkalosis have on pH and bicarbonate?
add base, increases them
69
what are the 3 other buffering systems, apart from bicarbonate?
Haemoglobin
Plasma proteins
Phosphate
70
what does haemoglobin buffer metabolically to produce?
CO2
71
what are the H+ mopped up by?
reduced haemoglobin (Hb)
72
what happens to Hb after O2 delivery to cells?
it is reduced
73
is O2 low or high in the lungs?
high
74
what does high O2 in the lungs do?
liberates CO2, removing the excess acid
75
In ECF, what is made possible by proteins
small amount of buffering
76
what are proteins composed of
AAs which contain acidic and basic R groups and are amphoteric
77
are carboxyl R groups strong or weak acids or bases
weak acids
78
Amino R groups strong or weak acids or bases
weak bases
79
why do phosphate play a minor role in ECF
due to relatively low concentration
80
when is phosphate a good urinary buffer and why
under normal conditions as there is little reabsorption
81
what is the Henderson-Hasselbalch equation
pH = pK + log10([HCO3-]/αPco2)
82
what does the Henderson-Hasselbalch equation predicts in Respiratory compensation
predicts that if the pH decreases then it is likely that the Pco2 will be increased
83
is the CO2 solubility (α) high or low in Henderson-Hasselbalch equation
low (0.03)
84
what is increased Pco2 detected by
Central chemoreceptors
Peripheral chemoreceptors
85
where are Central chemoreceptors located
brainstem
86
where are Peripheral chemoreceptors located
aortic arch
87
what happens if the pH drops
CO2 is increased
88
what detects a pH decrease
Detected by brainstem/peripheral chemoreceptors
89
what occurs if the pH drops and CO2 is increased
Causes increased ventilation to blow off CO2
90
when ventilation occurs to blow off CO2, what then happens
increases blood pH
negative feedback
91
what does the Henderson-Hasselbalch equation predicts in Renal Compensation
predicts that if the pH decreases then it is likely that bicarbonate will be decreased
92
how can the kidney compensate by
by regulating bicarbonate reabsorption and proton secretion
93
what is Renal Compensation more efficient at
restoring pH balance
94
For every bicarbonate absorbed how many H+ secreted into urine
1
95
In respiratory compensation, how is pH regulated
by change in CO2
96
how happens to Plasma [H+] in acidosis Renal Compensation
Plasma [H+] is increased
97
why is less HCO3- filtered in acidosis Renal Compensation
filtered as it is buffering the increased H+
98
why does urine becomes more acidic in acidosis Renal Compensation
Renal H+ secretion increases
99
how happens to Plasma [H+] in alkalosis Renal Compensation
Plasma [H+] decreases
100
why is less HCO3- filtered in alkalosis Renal Compensation
as it is less required for buffering
101
why is not all HCO3- reabsorbed in alkalosis Renal Compensation
because H+ availability is rate limiting
102
what happens to urine in alkalosis Renal Compensation
urine becomes more alkaline
103
what must be maintained
| to acidify urine during acidosis
gradient for H+ secretion
104
what helps to maintain the gradient of H+
If H+ is mopped up by buffers in urine
105
what is secreted H+ buffered by
Phosphate and Ammonia
106
what happens too Phosphate In acidosis
capacity is exceeded
107
what does ammonia + proton make
ammonium ion
108
where is ammonia secreted
in the kidney
109
is ammonia weak/strong acid/base?
Weak base
110
what is Ammonia produced from
glutamine metabolism
111
when is Production of Ammonia up-regulated
during acidosis
112
what does Ammonia in collecting ducts do
mops up urinary H+ during acidosis
113
what does an acid-base disturbance affects
pH, Pco2 and/or [HCO3-]
at least 2 out of 3 of them
114
when does Compensation comes into play in an acid-base disturbance
immediately
115
what does Compensation correct in an acid-base disturbance
Corrects pH change only
116
what is sacrificed in Compensation in an acid-base disturbance
Pco2 and HCO3- sacrificed to restore pH
117
what does Correction correct in an acid-base disturbance
Complete restoration of pH, Pco2 and HCO3-
118
4 types of of acid-base balance disorder
Respiratory acidosis
Respiratory alkalosis
Metabolic acidosis
Metabolic alkalosis
119
what is a change in pH that has a respiratory cause associated with
abnormal Pco2
120
what does an abnormal Pco2 gives rise to
gives rise to a change in carbonic acid-derived H+
121
what is a change in pH that has a metabolic cause associated with
altered [HCO3-] as a result of the participation of HCO3- in buffering abnormal [H+]
122
Respiratory Acidosis cause
Retention of CO2 (hypoventilation)
123
Respiratory Acidosis uncompensated result
pH decreases, HCO3- increases
124
Respiratory Acidosis compensated result
Increased reabsorption of HCO3-
Secretion of ammonium
HCO3- remains elevated
125
Acute intracellular buffering in Respiratory Acidosis time course
seconds or minutes
126
Chronic renal compensation in Respiratory Acidosis time course
days
127
3 Clinical causes of Respiratory Acidosis
Drug-induced depression of respiratory centres
Pulmonary oedema
Emphysema
128
Respiratory Alkalosis cause
Loss of CO2 (hyperventilation)
129
Respiratory Alkalosis uncompensated result
pH increases, HCO3- decreases
130
Respiratory Alkalosis compensated result
Decreased reabsorption of HCO3-
Decreased secretion of ammonium
HCO3- remains depressed
131
Acute intracellular buffering in Respiratory Alkalosis time course
seconds or minutes
132
Chronic renal compensation in Respiratory Alkalosis time course
days
133
4 Clinical causes of Respiratory Alkalosis
Anxiety, fear
Pain
Aspirin poisoning
High altitude
134
Metabolic Acidosis cause
Loss of HCO3- or addition of H+ to plasma
135
Metabolic Acidosis Uncompensated result
pH decreases, HCO3- decreases
136
Metabolic Acidosis compensated result
Respiratory compensation (increased ventilation) partially restores pH
Renal compensation completes the restoration of pH by increasing reabsorption of HCO3-
137
Acute respiratory of Metabolic Acidosis Time course
seconds or minutes
138
Chronic renal compensation of Metabolic Acidosis Time course
days
139
4 Clinical causes of Metabolic Acidosis
Diabetic keto-acidosis (abnormal fat metabolism)
Diarrhoea (loss of HCO3-)
Heavy exercise (addition of lactic acid)
Renal failure (reduced secretion of protons)
140
Metabolic Alkalosis cause
Addition of HCO3- or loss of H+ from plasma
141
Metabolic Alkalosis Uncompensated result:
pH increases, HCO3- increases
142
Metabolic Alkalosis compensated result
Respiratory compensation (increased ventilation) partially restores pH (C)
Renal compensation completes the restoration of pH by decreasing reabsorption of HCO3-
143
Acute respiratory in Metabolic Alkalosis Time course
seconds and minutes
144
Chronic renal compensation in Metabolic Alkalosis Time course
days
145
2 Clinical causes of Metabolic Alkalosis
Ingestion of antacids
| Vomiting (loss of HCl)
146
what is respiratory compensation response limited by
hypoxaemia which counteracts response via chemoreceptors
147
what is the most effective at causing compensation
the renal response of in metabolic alkalosis
