Cellular Receptors — Transcript

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1. 0:01hi there and welcome back to an
2. 0:03understanding medications since we're
3. 0:05going to begin our discussions on
4. 0:08medications that work on cellular
5. 0:09receptors in this chapter and it's
6. 0:12really important that we have a good
7. 0:14clear picture of what cellular receptors
8. 0:18are and also have a general idea of the
9. 0:23four different types of cellular
10. 0:24receptors so those are going to be the
11. 0:27aims of this lesson
12. 0:30human cells are made up of phospholipid
13. 0:33bilayer the phospholipid bilayer is
14. 0:37constantly moving a little bit and that
15. 0:40bilayer is held together by various
16. 0:42attractant and repelling properties of
17. 0:46the molecules so there's Van Der Val's
18. 0:50forces which will allow the lipid
19. 0:54soluble tails to attract each other and
20. 0:57then there's hydrogen bonding that's
21. 1:00going to allow the heads to be attracted
22. 1:03to each other on the surface of the
23. 1:05phospholipid bilayer there is different
24. 1:08proteins and these proteins include
25. 1:11structural proteins there's enzymes that
26. 1:15speed up reactions there's channels and
27. 1:18transport carrier molecules and there's
28. 1:22also cellular receptors and most of our
29. 1:26cellular receptors three of the four
30. 1:29different types of cellular receptors
31. 1:32are on the cell surface they're
32. 1:36transmembrane proteins in other words
33. 1:38what they do is they span all the whole
34. 1:41distance of the phospholipid bilayer
35. 1:43from the outside of the cell to the
36. 1:45inside of the cell
37. 1:47and being a receptor it's going to
38. 1:50receive something so what is it going to
39. 1:53receive the thing that the cellular
40. 1:55receptors receive is called The
41. 1:58receptors ligand or sometimes called
42. 2:02ligand
43. 2:04this is a representation of the insulin
44. 2:07receptor the insulin receptor is an
45. 2:10enzyme-linked receptor and it's located
46. 2:13on the outer surface of certain cells
47. 2:17this type of receptor is not on all
48. 2:20cells in the body but rather just the
49. 2:23cells that need that receptor
50. 2:26when the receptor is bound by its ligand
51. 2:30the natural substance for which the
52. 2:32receptor was made in this case insulin
53. 2:34that results in a change in the shape of
54. 2:39the protein it results in a
55. 2:42conformational change
56. 2:44and that ultimately results in a Cascade
57. 2:49of events within the cell
58. 2:52so it's ultimately responsible for
59. 2:55messaging the cell or a protein
60. 2:58associated with the receptor to do
61. 3:01something
62. 3:02in this case it signals an increase in
63. 3:06the amount of glucose transport carrier
64. 3:08molecules being placed on the surface of
65. 3:11the cell so you can see how the pancreas
66. 3:15has used insulin as the message for the
67. 3:19muscle cells to react in a given way and
68. 3:23the g protein linked receptor acts in a
69. 3:26similar way where The Binding of the
70. 3:28natural ligand results in a cellular
71. 3:31response
72. 3:33the ligand-gated Ion channel is a bit
73. 3:37different it's a receptor that undergoes
74. 3:40that conformational change after The
75. 3:43Binding of the natural ligand but that
76. 3:48change just opens up a channel for
77. 3:52positively or negatively charged
78. 3:55particles to go through the cell's
79. 3:58surface
80. 3:59and finally there's the intracellular
81. 4:02receptors the ligands for those have to
82. 4:06be lipid soluble in order to get through
83. 4:09the phospholipid bilayer and when those
84. 4:12ligands bind to their receptor
85. 4:15the entire receptor ligand complex goes
86. 4:20into the nucleus of the cell binds to
87. 4:23the DNA and simply put those ligands are
88. 4:28going to affect the production of
89. 4:31proteins that the cell makes in summary
90. 4:35of this lesson cellular receptors are
91. 4:38proteins that are on the surface of the
92. 4:41cell or they're also inside the cell
93. 4:44intracellular receptors are possible as
94. 4:47well
95. 4:48and those proteins as they're Bound by
96. 4:51the natural ligand they're going to
97. 4:54result they're going to undergo a
98. 4:57conformational change in the protein a
99. 5:00change in the structure of the protein
100. 5:02and that's going to result in a Cascade
101. 5:04of events inside this cell
102. 5:07and therefore the ligand and the
103. 5:10cellular receptors are are way of
104. 5:13communicating between one cell and
105. 5:17another cell and we'll find out how our
106. 5:20medications use those receptors because
107. 5:24most of our medications use cellular
108. 5:27receptors for their therapeutic actions
109. 5:35we've just taken a look at the major
110. 5:38types of cellular receptors and we've
111. 5:41noted that most of our medications bind
112. 5:43to one of those receptors to perform
113. 5:46their therapeutic actions
114. 5:48recall that cellular receptors are the
115. 5:51cell's way of receiving Communications
116. 5:54from other cells or other parts of the
117. 5:57body
118. 5:57when the receptor is bound by the
119. 6:00natural ligand or a drug that mimics the
120. 6:03natural ligand that is the signal for
121. 6:07the cell to do something for instance
122. 6:09The Binding of the insulin receptor on
123. 6:12muscle cells increases the number of
124. 6:15glut4 Transport carrier proteins on the
125. 6:18cell surface
126. 6:20so our cells can regulate the number of
127. 6:24proteins that are embedded in the cell
128. 6:27surface and just like that increase in
129. 6:30number of Transport carrier proteins the
130. 6:33cell has the ability to increase or
131. 6:36decrease the number of the cell
132. 6:38receptors on the cell surface
133. 6:42so think about that this cell has the
134. 6:45ability to increase or decrease the
135. 6:49number of cellular receptors so we can
136. 6:52actually alter the number of messages
137. 6:56that go into the cell can't we
138. 7:00let's take an example we have natural
139. 7:02opioids in the body that decrease the
140. 7:05transmission of pain
141. 7:06our medications called the opioids bind
142. 7:10to those same receptors and they also
143. 7:14decrease the transmission of pain but
144. 7:17when a person takes pharmacological
145. 7:19doses of opioids for about three weeks
146. 7:22or more the cells themselves decide that
147. 7:26there's too many receptors on the cell
148. 7:28surface
149. 7:30so right now hypothesize what will
150. 7:32happen to the perception of pain when
151. 7:35the cells themselves decrease the number
152. 7:39of opioid pain relieving receptors
153. 7:43a the perception of pain will stay the
154. 7:46same B the perception of pain will
155. 7:49increase see the perception of pain will
156. 7:52decrease
157. 7:54and you are correct if you said B the
158. 7:57perception of pain will increase one of
159. 8:00the biggest problems with using
160. 8:02pharmacological doses of opioids is the
161. 8:06fact that the cells themselves recognize
162. 8:09that there is an abundance of opioids in
163. 8:12the system and they respond by taking
164. 8:15some of the receptors the opioid
165. 8:18receptors off the cell surface they pull
166. 8:22those receptors off the cell surface
167. 8:24they degrade them and use the parts for
168. 8:27other things and that decreases the
169. 8:30number of cellular receptors and
170. 8:32increases the perception of pain
171. 8:35and that explains why people who take
172. 8:38opioids consistently for a few weeks
173. 8:41will go back to the practitioner looking
174. 8:43for a stronger opioid or looking for
175. 8:46higher doses
176. 8:48they're actually experiencing more pain
177. 8:52instead of less pain with the same
178. 8:54insults
179. 8:56and this type of compensation doesn't
180. 8:59occur at every receptor but it is
181. 9:01oftentimes the reason for the rebound
182. 9:04effects of some of our medications and
183. 9:07in those situations it's very important
184. 9:09not to take the medication for longer
185. 9:13than recommended