Equilibrio ácido base - Buffer Respiratorio - Video 7 — Transcript

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1. 0:01Howdy, colleagues? Welcome to this new
2. 0:03video number seven on arterial blood
3. 0:06gases. Today we will talk about the
4. 0:09respiratory mechanism as a regulator of
5. 0:11acid-base balance. In previous videos
6. 0:15we saw that there are different
7. 0:17mechanisms responsible for regulating
8. 0:19any alteration of the acid-base balance
9. 0:21and we saw the dampers or woofers.
10. 0:24Today we will talk about the
11. 0:25respiratory system, which is the second
12. 0:27line of defense against any alteration
13. 0:29of the acid-base balance. It is also
14. 0:31considered a mediate system, since it
15. 0:33takes a few minutes to act when it
16. 0:36detects an alteration and it is mainly
17. 0:38based on retaining or eliminating CO2.
18. 0:42Since we are talking about CO2, let's
19. 0:44remember that this is the result of
20. 0:46cellular metabolism. And as a result of
21. 0:50cellular metabolism, there is a
22. 0:52constant production of CO2. This
23. 0:56metabolism maintains a CO2
24. 0:58concentration of 1.2 moles per liter,
25. 1:00which is equivalent to a PCO2 of 45 mm
26. 1:03of merco. Any alteration of CO2 will
27. 1:07act directly on the partial
28. 1:09concentration of CO2, whether one
29. 1:11decreases or increases, the other will
30. 1:14increase. From previous videos, we
31. 1:18recall that carbon dioxide or CO2 is
32. 1:20the acidic part of the acid-base
33. 1:23balance, since when hydrated, it will
34. 1:26be converted into carbonic acid with
35. 1:28the help of carbon dioxide, which will
36. 1:31quickly dissociate into bicarbonate and
37. 1:34hydrogen ions or protons. And let's
38. 1:37remember that these are what will
39. 1:39determine the pH of the extracellular
40. 1:42fluid. And ventilation is responsible
41. 1:46for regulating the concentration of CO2
42. 1:49within the extracellular fluid, since
43. 1:51if we are hyperventilating, this will
44. 1:54favor the elimination of more CO2,
45. 1:57which will obviously cause a decrease
46. 2:00in PCO2, and this will cause the
47. 2:02concentration of hydrogen ions to
48. 2:04decrease and with it, the pH can
49. 2:07increase. But if we are facing
50. 2:10hypoventilation, this will cause CO2 to
51. 2:13be eliminated, which can cause CO2 to
52. 2:16begin to accumulate in the
53. 2:17extracellular fluid, which will favor
54. 2:20an increase in PCO2 with a tendency to
55. 2:23increase the concentration of hydrogen
56. 2:25ions and therefore a decrease in pH. As
57. 2:31we have seen, ventilation has a direct
58. 2:33influence on the concentration of
59. 2:35hydrogen ions in the extracellular
60. 2:37fluid through the elimination or
61. 2:39retention of CO2. And this mechanism is
62. 2:4250 to 70%effective in regulating the
63. 2:45concentration of hydrogen ions. In
64. 2:49other words, this mechanism is twice as
65. 2:52powerful as all the woofers we saw in
66. 2:54previous videos. Another respiratory
67. 2:59mechanism by which acid balance is
68. 3:01maintained is through feedback
69. 3:03regulation, which is determined by the
70. 3:05concentration of hydrogen ions in the
71. 3:08extracellular fluid. If we are faced
72. 3:11with an increase in the concentration
73. 3:14of hydrogen ions, that is, in acidosis,
74. 3:16the brain will detect this and send
75. 3:18information to the lungs so that they
76. 3:20begin to hyperventilate and, with this,
77. 3:22increase the elimination of CO2, which
78. 3:24will decrease its concentration and,
79. 3:26therefore, the PCO2; and with this, by
80. 3:29negative feedback, the concentration of
81. 3:31hydrogen ions will decrease and in this
82. 3:33way we can maintain a pH within the
83. 3:35normal range. But if, on the contrary,
84. 3:39we are facing a decrease in the
85. 3:41concentration of hydrogen ions, that is
86. 3:43, in the face of alkalosis, the brain
87. 3:45will also detect this and will order a
88. 3:47decrease in ventilation, that is, it
89. 3:49will begin to hypoventilate, therefore,
90. 3:51it will retain CO2 and increase its
91. 3:54concentration. Therefore, PSO2 will
92. 3:56also increase and with this we will
93. 3:58achieve an increase in the
94. 3:59concentration of hydrogen ions and thus
95. 4:01also maintain the pH within the normal
96. 4:04range. For this to be carried out, it
97. 4:09is necessary for CO2 to be transported
98. 4:11from the place where it is produced to
99. 4:14the lungs. And there are three ways of
100. 4:16transporting CO2. The first is in free
101. 4:19form in the blood plasma and of 100%of
102. 4:22the CO2 produced, 8%is transported in
103. 4:26this way. The CO2 produced will diffuse
104. 4:29into the capillary and through the
105. 4:32bloodstream it will reach the lungs and
106. 4:34will be eliminated through exhalation.
107. 4:38The other way is bound to the red blood
108. 4:41cell and 22%of the CO2 produced is
109. 4:44transported. The CO2 will diffuse into
110. 4:47the capillary, bind to the erythrocyte,
111. 4:50and this will serve as a means of
112. 4:53transport to reach the lungs, which
113. 4:56will diffuse into the alveoli by
114. 4:58pressure gradient and will also be
115. 5:01eliminated through exhalation. Finally,
116. 5:06it is transported in the form of
117. 5:08bicarbonate, and of 100%of the CO2
118. 5:10produced, 70%is transported in the form
119. 5:12of bicarbonate. In the same way, the
120. 5:15CO2 will diffuse into the capillary and
121. 5:18reach the red blood cell, but this time
122. 5:21, inside the red blood cell, it will be
123. 5:24hydrated and converted into carbonic
124. 5:26acid. This is a process that we have
125. 5:28already seen and that you are already
126. 5:29familiar with. This carbonic acid,
127. 5:32let's remember, will produce a hydrogen
128. 5:34ion, a proton, that is, the acidic
129. 5:36element, but it will quickly be
130. 5:38buffered by hemoglobin, as we saw in
131. 5:40the previous video, as a physiological
132. 5:42buffer for proteins. It will also
133. 5:45release bicarbonate, which will diffuse
134. 5:47into the extracellular fluid, but for
135. 5:49each bicarbonate that leaves the
136. 5:51erythrocyte, chlorine must enter to
137. 5:53maintain the balance within it. The
138. 5:57bicarbonate already in the
139. 5:59extracellular fluid will be directed
140. 6:01through the bloodstream to the lungs.
141. 6:05Once in the lungs, it will wait for the
142. 6:07erythrocyte to oxygenate and once it is
143. 6:10oxygenated, it will release the
144. 6:13hydrogen ion that the hemoglobin had.
145. 6:16It will bind to the bicarbonate to form
146. 6:18carbonic acid, a process that you are
147. 6:20also familiar with, it will split into
148. 6:23water and CO2 and the CO2 will be
149. 6:25eliminated through exhalation and water
150. 6:27can also be eliminated in the same way.
151. 6:31As we saw, there are three ways of
152. 6:33transporting CO2 so that this
153. 6:35regulation of the acid-base balance can
154. 6:37be carried out. Therefore, we have seen
155. 6:40that ventilation is a respiratory
156. 6:42regulatory mechanism of the acid-base
157. 6:44balance. It is considered a mediated
158. 6:47system, it is also physiological and
159. 6:49determines the elimination or retention
160. 6:51of CO2. This will modify the
161. 6:54concentration of hydrogen ions and
162. 6:56therefore the result is to raise or
163. 6:59lower the pH to keep it within its
164. 7:01normal range. Well, we have reached the
165. 7:05end of this video. Remember to share it
166. 7:07with your colleagues and peers.