Muscle Physiology 3.2 - Cardiac Muscle — Transcript

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1. 0:02Okay, we're now on the last video
2. 0:04finally.
3. 0:06So this time we'll talk about the
4. 0:07Kardiac muscle here. Actually briefly
5. 0:10lang to kasi we will talk about the
6. 0:11cardiac muscle again in the third long
7. 0:14exam when we go to the cardiovascular
8. 0:16module. So here parang introductory lang
9. 0:20discuss lang din.
10. 0:22Okay. And we just compare it with the
11. 0:24scarc with the skeletal and smooth so
12. 0:26that you can see the difference among
13. 0:28the three muscle type. So of course we
14. 0:31talk about the structure briefly. Okay
15. 0:33for sure na-discuss na rin to sa
16. 0:34osmosis. Talk about this is very
17. 0:36important the excitation contraction
18. 0:38coopling and regulation. The pattern of
19. 0:40contraction here is similar all
20. 0:42throughout. Kasi ang heartbeat naman
21. 0:43natin ganun naman talaga yan no? Hindi
22. 0:45naman nagbabago-bago ang heartbeat natin
23. 0:47unless you you have a problem, you have
24. 0:50arithmya. But anyway, uh cardiac muscle
25. 0:53with your skeletal muscle, both of them
26. 0:54are streated. Both of them have
27. 0:56troponines I CT. Uh both of them
28. 1:00sarcoplasmic reticulum although less
29. 1:02developed both of them have tubius
30. 1:05that's why they have striation. The
31. 1:07unique is that it's involuntary, okay?
32. 1:10And the presence of what they call the
33. 1:11intercalated t and there's a lot of
34. 1:15mitochondria because I'll tell you
35. 1:17already as early as now that cardiac
36. 1:19muscle mainly utilize their energy
37. 1:22through the oxidative pathway sa mga
38. 1:24fats. Okay? Lalo na fats talaga. Okay.
39. 1:28They are not they cannot capable of
40. 1:30doing contraction pag walang oxygen. No,
41. 1:33that's not good. Heart muscle the can
42. 1:36die in the absence of oxygen in just one
43. 1:40to 5 minutes. Okay? That's why that
44. 1:42leads to heart attack basically.
45. 1:46What also unique is that your cardiac
46. 1:47muscle have abundant connective tissue
47. 1:49kasi since they contract ah non-stop 'di
48. 1:53ba? Hindi naman pwede mag-stop ang
49. 1:54heartbeat eh. They need a lot of
50. 1:57support, structural support like your uh
51. 1:59collagen, your elastic fibers, no to
52. 2:02allow them to recoil, contraction, blah
53. 2:05blah blah. Okay, but I'll leave that to
54. 2:07anatomy. So I think you already know
55. 2:09this this was already discussed in
56. 2:11osmosis that the cardiac muscle able to
57. 2:14transmit their action potential from one
58. 2:17cardiac muscle to another cardiac muscle
59. 2:19through the intercalated dis because it
60. 2:21contains abundant cap sunction basically
61. 2:24electrical synapse. Okay? So action
62. 2:28potential neural. Okay ha? Tandaan niyo
63. 2:30action potential to neural. So the
64. 2:32action potential travers quickly through
65. 2:34entire kajak muscle because of this
66. 2:37intercalated dis. But we have to take
67. 2:40note in skeletal muscle it's the motor
68. 2:42neuron ba the somatic neuron. In the in
69. 2:47the smooth muscles usually it's the
70. 2:48autonomic neurons. Kung hindi autonomic
71. 2:51hormones and stretching. Ito sa cardiac
72. 2:54the action potential originate from the
73. 2:57pacemaker. The SA node. It's a
74. 2:59specialized structure in your heart that
75. 3:01is capable of producing its bit on its
76. 3:05own without
77. 3:07interferences.
78. 3:09But again uh I'll let the third LE
79. 3:13discussion that. Okay. So unique feature
80. 3:15in your KJAC muscle is ganito siya yung
81. 3:18kanyang action potential picture. Okay?
82. 3:21Again this will be further emphasized
83. 3:24okay in details sa third long exam not
84. 3:27now. So let's talk about we're done with
85. 3:30excitation. The excitation of the heart
86. 3:33is basically from the pacemaker. Let's
87. 3:35talk about contraction. So since they
88. 3:37are striated and since they are similar
89. 3:40to your skeletal muscle in the presence
90. 3:41of sarcoplasmic reticulum, presence of
91. 3:45um uh presence of uh ranine
92. 3:49receptors,prinosines,
93. 3:52ratio blah blah, halos same lang. So
94. 3:55what I will discuss here is just the
95. 3:57unique or difference with your skeletal
96. 4:01muscle. So same there is a sarcolema
97. 4:04there's an action potential. Okay, that
98. 4:06goes to your tubules and activate this
99. 4:09channel, calcium channel. But this
100. 4:11channel is different from the skeletal
101. 4:14muscle. The channel is what we call
102. 4:16calcium voltage 1.2. 1.1 sa skeletal,
103. 4:201.2 sa DHPR. So this is calcium 1.2. So
104. 4:26this will cause once this is activated
105. 4:29this will cause the calcium in the
106. 4:32extracellular fluid to go inside. and
107. 4:35activates your calcium in to activate
108. 4:39your RYR in the sarcoplasmic reticulum.
109. 4:43Ulitin ko the DHPR in the cardiac muscle
110. 4:47or CV 1.2
111. 4:49will open allowsum to go inside okay
112. 4:53from extracellular to intracellular and
113. 4:55activate the RYR to release the calcium.
114. 4:58This is the calcium induced calcium
115. 5:01release mechanism a lot similar to your
116. 5:03smooth muscle.
117. 5:05Okay. A lot similar to your smooth
118. 5:07muscle. In your skeletal we talk about
119. 5:10that the DHPR is connected with RYR.
120. 5:15Activation of DHPR causes the mechanical
121. 5:19conformational change of the DHPR
122. 5:22leading to the activation of where RYR.
123. 5:25Ito open of calcium channel. Calcium
124. 5:29goes inside. Calcium activates RYR.
125. 5:32Calcium from the SR goes out. Calcium
126. 5:36induce calcium release. Very important
127. 5:39difference between the two, the skeletal
128. 5:42and the cardiac.
129. 5:44Okay? That's why
130. 5:46cellular calcium is very important.
131. 5:48That's why uh patients who have
132. 5:50decreased calcium extracellular no meron
133. 5:53silang hypocalcemia that can really
134. 5:55affect the cardiac muscle that can lead
135. 5:58to um poor muscle contraction of the
136. 6:00heart. Okay, nangyayari 'yan. So,
137. 6:03nagkakaroon ng heart arrest, cardiac
138. 6:05arrest just because there is
139. 6:07hypocalcenia. So 'yun
140. 6:10ah yan. So contraction strength is not
141. 6:14regulated by temporal. So there's no
142. 6:15temporal spatial summation here. Ha in
143. 6:18skeletal ' ba pwede mong i-tetanize ang
144. 6:21cardiac ang skeletal muscle. May titanic
145. 6:24contraction ang skeletal sa heart.
146. 6:26Walang ganon no? Walang ganon eh. The
147. 6:29regulation of basically the contraction
148. 6:32of the cardiac muscle is either you
149. 6:34increase the strength, okay? Papalakasin
150. 6:36mo iyung contraction niya by more ano
151. 6:40ba? More forced or you regulate the
152. 6:44electrolyte levels maintaining them in a
153. 6:46normal value again uh youl talk this
154. 6:49length tension relationship sa third LE
155. 6:51na not now. Okay? Not now. Levels of
156. 6:55intracellular calcium is not regul is
157. 6:57regulated. Okay, well regulated but not
158. 7:00as high as in the skeletal muscle. Kasi
159. 7:02sa skeletal muscle purely the calcium
160. 7:05inside the sarcoplastic reticulum is the
161. 7:08one that will cause
162. 7:10dito. Okay. Very important yung
163. 7:12extracellular calcium.
164. 7:16So the rest the the the ah ano to cross
165. 7:20bridge cycle the same no hindi ko na
166. 7:22idi-discuss yan. The same troponin se
167. 7:24actin myine crossb cycle blah blah blah.
168. 7:27Sa relaxation ganun din. The presence of
169. 7:29cirka allows costum to goes inside. But
170. 7:31the difference with your skeletal sa
171. 7:34skeletal you just have this one channel
172. 7:37ba yan lang.
173. 7:39Wala kang ganito sa skeletal.
174. 7:42But now in the cardiac there is what we
175. 7:44call the calcium sodium exchanger. Ayan.
176. 7:48Ayan. So this is one way of where you
177. 7:51extrude calcium out. Okay? Extrude
178. 7:54calcium out. Wait lang doc. Akala ko ba
179. 7:57extraily
180. 7:59mas mataas ang calcium
181. 8:03dito? Mababa ang calcium. So how can you
182. 8:06go against the gradient 'di ba? That's
183. 8:09why you need to utilize the active
184. 8:11transporter the primary active
185. 8:14transporter. This was discussed by Dr.
186. 8:15Hassintor. So review lang siya. So you
187. 8:18need this okay this active transporter
188. 8:21to stimulate or to activate this
189. 8:25secondary active transporter exchanger
190. 8:28to allow the calcium to be extrudeed
191. 8:29out. Kasi ang mangyayari dito dahil
192. 8:31tinanggal mo si sodium si sodium mataas
193. 8:33dito ladami ang sodium dito. Okay?
194. 8:37Sodium will go here in exchange will
195. 8:39your calcium. Okay. Now, uh sabi ko
196. 8:43kanina before I move here, sabi ko
197. 8:46kanina, one mechanism to increase the
198. 8:49strength of contraction of your heart is
199. 8:51the presence of calcium. Okay? More
200. 8:53calcium here, more contraction. So what
201. 8:57can doctors do to make sure calcium
202. 9:01still remains here? So sometimes
203. 9:05certain medication inhibit this one.
204. 9:09Okay? So if you inhibit this primary
205. 9:11active transporter this will not
206. 9:13activate.
207. 9:15So if this is not activated
208. 9:18calcium will maintain
209. 9:20be high in the
210. 9:23cycoplasm or basically in the cytoplasm
211. 9:25of your cardiac muscle thus allowing
212. 9:27contraction to occur pa rin. So that's
213. 9:31one way of mechanism, one drug that can
214. 9:34lead to stronger cardiac muscle.
215. 9:36Especially if a patient have heart
216. 9:37problem nao, heart failure na. The heart
217. 9:39is not contracting very well, mahina. So
218. 9:42magbibigay sila ng gamot to inhibit this
219. 9:44primary active transporter. Okay? So
220. 9:47yun. So that's it. That's all thing that
221. 9:49you have to know inj muscle. To
222. 9:51summarize it. Another pala no iyung
223. 9:5380ps. Calcium atpas wala sa guidon eh.
224. 9:55Pero sa ibang books like in vern there's
225. 9:57also calcium that I also discuss in your
226. 10:01smooth muset. So to summarize it, so you
227. 10:03have your action potential from the
228. 10:04pacemaker going to the titubule. Ang
229. 10:07difference sa
230. 10:10ang potential ng ng ah ng skeletal is
231. 10:14sodium dito calcium. Okay? Then because
232. 10:17of this you will activate your uh your
233. 10:21sodium sorry your calcium voltage 1.2.
234. 10:25Calcium goes inside. Activate your RYR.
235. 10:28Calcium goes out. Calcium goes to the my
236. 10:30filament causing contraction.
237. 10:33Now, tapos na. Ayaw mo na mag-contract '
238. 10:35ba? Gusto mo na magpahinga. Ayan oh. Ah
239. 10:37so with that uh calcium goes back in
240. 10:40whether through the circ or through this
241. 10:43mechanism.
242. 10:45If you take a look at this this picture,
243. 10:47okay, so the contraction is quite
244. 10:49prolonged because calcium no is also
245. 10:53prolong no. Matagal yung taas ng calcium
246. 10:55because of this one. Okay? Because
247. 10:57calcium goes inside. So matagal may
248. 10:59plato effect din siya here. Okay?
249. 11:04So other hindi pala last slide yun. The
250. 11:07regulation again intracellular calcium I
251. 11:08talk about it. So if you increase the
252. 11:10calcium level the force of contraction
253. 11:11increases. Sometimes some medication
254. 11:14like a ligant a ligant like
255. 11:17epinephrine okay may bind to a G protein
256. 11:20and that G protein causes calcium
257. 11:22increase. Okay? So kunyari ito this if
258. 11:25you take a look at this one. So nagbigay
259. 11:27siya ng gamot isoprotenerol. Okay? It's
260. 11:29a catecolits.
261. 11:31It's a betaagonist because of that
262. 11:33there's increasing calcium.
263. 11:36How what mechanism similar to your
264. 11:37smooth muscle pero ito card and that
265. 11:40will lead to increase force okay yun
266. 11:43other will be passive tension frank
267. 11:45starling law of the heart phospholamban
268. 11:47that will be discussing the third le I
269. 11:49will not ask this ha itong dalawa don't
270. 11:51worry ah basically just want you to know
271. 11:54the difference of your kiac with your
272. 11:56skeletal muscle and smooth muscle so to
273. 11:59end again we down to this table we talk
274. 12:03about Okay, this two. How about Kajak?
275. 12:07Yes, we talk about the morphology. We
276. 12:08talk about the excitation no coming from
277. 12:10the pacemaker and the contraction almost
278. 12:12similar to your skeletal mga sir. The
279. 12:14source of calcium saan ba galing? The
280. 12:16rate and duration of contraction as
281. 12:18compared with this two and the
282. 12:19metabolism. We talk about that in the
283. 12:21first slide of this video. Okay. So with
284. 12:23that uh that's the end of the muscle
285. 12:27fishology module. Again
286. 12:30despite of difference all of them will
287. 12:33cause contraction when there's an
288. 12:34increase in your calcium level cytosolic
289. 12:37calcium level. In the end, I would like
290. 12:39to end my lecture with this first. Uh,
291. 12:42but for those who are weak, okay, not
292. 12:45only physically but spiritually, wait on
293. 12:48the Lord for he will renew our strength.
294. 12:51They shall mount up with wings like
295. 12:53eagles. They shall run and not be really
296. 12:56they shall walk and not be faed. So, uh,
297. 12:59with that, these are my references and
298. 13:02uh very important to read if ever giton,
299. 13:05okay, and burn.
300. 13:07that thank you very much for listening.