255:
535:. However this G-protein works by inhibiting, the cAMP pathway, therefore, preventing the sympathetic nervous system from increasing heart rate. As well as this, in the SAN, the G-protein activates specific potassium channel, that opposes action potential initiation (see
263:
The increase in Ca, produced by CICR, now does two things. Firstly, it binds to the intracellular side of the DHPR, signalling the channels to close and preventing further influx of Ca into the cell. Secondly Ca indirectly activates
258:
Figure 1: Calcium binding to troponin, exposes sites on the actin filaments, to which myosin binds. Using ATP, myosin moves the actin along. The myosin releases the actin, resets itself and binds to another actin binding
791:
Monfredi, Oliver; Dobrzynski, Halina; Mondal, Tapas; Boyett, Mark R.; Morris, Gwilym M. (2010). "The
Anatomy and Physiology of the Sinoatrial Node-A Contemporary Review: SINOATRIAL NODAL ANATOMY AND PHYSIOLOGY".
328:, is then used, as a source of energy, to help move the myosin head, carrying the actin. As a result, the actin slides across the myosin filament shortening the muscle. This is called a power stroke.
356:
Contraction ends when the Ca is removed from the cell. When this happens, the troponin changes back to its original shape, blocking the binding sites on
344:
further. This process continues, with the myosin head moving in a motion similar to that of an oar rowing a boat, until the
528:
1009:
527:
Parasympathetic nerves work by releasing a neurotransmitter called acetylcholine (ACh) which binds to specific receptor (
300:, which is bound to the actin filament. This binding causes a shape change in the troponin which exposes areas on the
1029:"Processes that remove calcium from the cytoplasm during excitation-contraction coupling in intact rat heart cells"
70:) at a rate between 60 and 100 beats every minute, when the body is at rest. This rate can be altered, however, by
401:
243:
107:
102:
into mechanical energy (contraction) of the muscle. This is achieved in a region of the muscle cell, called the
457:
453:
449:
79:
558:"How does the shape of the cardiac action potential control calcium signaling and contraction in the heart?"
46:
to beat in a controlled manner, without the need for conscious input. EC coupling results in the sequential
425:
75:
945:"A simplified local control model of calcium-induced calcium release in cardiac ventricular myocytes"
1095:
465:
385:
175:
139:
135:
99:
27:
195:
194:, that allows Ca to pass into the cell. This increase in Ca, then binds to and activates another
440:. This activates a protein, called a G-protein and results in a series of reactions (known as a
513:
485:
441:
321:
207:
203:
191:
183:
63:
956:
215:
199:
146:, as impulses, passing from one cell to the next through channels, in structures known as
8:
1008:
Lodish, H.; Berk, A.; Zipursky, L.S; Matsudaira, P.; Baltimore, D.; Darnell, J. (2000).
960:
1061:
1028:
985:
944:
920:
887:
863:
828:
768:
735:
654:
619:
590:
557:
517:
497:
489:
405:
397:
389:
381:
361:
345:
273:
235:
219:
211:
95:
87:
67:
47:
31:
711:
678:
1066:
1048:
990:
972:
925:
907:
868:
850:
809:
805:
773:
755:
716:
698:
659:
641:
595:
577:
521:
531:) on the sarcolemma of both SAN cells and ventricular cells. This again activates a
1056:
1044:
1040:
980:
964:
915:
899:
858:
840:
801:
763:
747:
706:
690:
649:
631:
585:
569:
481:
477:
437:
417:
254:
536:
493:
469:
373:
365:
281:
239:
231:
223:
171:
163:
127:
123:
968:
573:
392:
out of the cell, in exchange for 3 sodium ions being pumped into the cell, the
336:
and resets itself back to its original position, binding to another part of the
1090:
1013:
943:
Hinch, R.; Greenstein, J. L.; Tanskanen, A. J.; Xu, L.; Winslow, R. L. (2004).
903:
421:
393:
341:
227:
214:
store within the cell and is located very close to the T-tubule. Activation of
119:
1084:
1052:
976:
911:
854:
845:
759:
702:
645:
581:
509:
325:
190:, and are activated by the action potential. Activated DHPRs open, forming a
147:
994:
929:
872:
813:
777:
720:
663:
599:
464:
involved in action potential initiation, speeding up the production of the
1070:
636:
501:
461:
269:
486:
L-type calcium channels (also known as dihydropyridine receptors (DHPR))
184:
L-type calcium channels (also known as dihydropyridine receptors (DHPR))
751:
429:
159:
143:
736:"Model of calcium-induced calcium release mechanism in cardiac cells"
694:
532:
445:
433:
369:
317:
297:
187:
179:
167:
103:
98:, which is responsible for converting the electrical energy of the
829:"Gap junction modulation and its implications for heart function"
618:
Gordan, Richard; Gwathmey, Judith K.; Xie, Lai-Hua (2015-04-26).
556:
Santana, Luis F.; Cheng, Edward P.; Lederer, W. Jonathan (2010).
505:
473:
265:
360:
and preventing the formation of crossbridges. This decrease in
329:
309:
305:
293:
83:
71:
35:
790:
377:
357:
337:
333:
313:
301:
289:
285:
277:
131:
55:
51:
43:
39:
26:) describes the series of events, from the production of an
1007:
827:
Kurtenbach, Stefan; Kurtenbach, Sarah; Zoidl, Georg (2014).
733:
620:"Autonomic and endocrine control of cardiovascular function"
734:
Wong, A. Y.; Fabiato, A.; Bassingthwaighthe, J. B. (1992).
59:
42:. This process is of vital importance as it allows for the
942:
826:
324:
which is produced by an intracellular structure called a
91:
202:, located on the membrane of a structure known as the
1027:
Balke, C. W.; Egan, T. M.; Wier, W. G. (1994-02-01).
679:"Calcium and the heart: a question of life and death"
492:, increasing the rise in Ca within the contractile
555:
340:and producing another power stroke, shortening the
230:. This means that the initial flow of Ca into the
153:
617:
1082:
416:Sympathetic nerves work by releasing a protein (
348:level within the cell decreases (see figure 1).
178:to travel into the centre of the cell. Special
1026:
351:
888:"Cardiac T-Tubule Microanatomy and Function"
562:Journal of Molecular and Cellular Cardiology
539:for more details), thus slowing heart rate.
122:is a group of specialised cells, called the
1010:"Muscle: A specialized Contractile machine"
516:for more details), speeding up the rate of
1060:
984:
919:
862:
844:
767:
710:
653:
635:
589:
472:for more detail). cAMP also, activates a
74:that work to either increase heart rate (
885:
253:
66:) and then around the rest of the body (
886:Hong, TingTing; Shaw, Robin M. (2017).
218:causes it to open, releasing even more
17:Cardiac excitation-contraction coupling
1083:
244:calcium induced calcium release (CICR)
226:, this release of calcium is called a
794:Pacing and Clinical Electrophysiology
683:The Journal of Clinical Investigation
676:
249:
28:electrical impulse (action potential)
1020:
613:
611:
609:
444:) that leads to the production of a
424:which binds to a specific receptor (
386:Sarcolemmal sodium-calcium exchanger
936:
879:
820:
784:
727:
670:
549:
376:. The main pumps involved are: the
308:filament binds. The binding of the
13:
242:, therefore the process is called
126:. These cells, unlike most other
14:
1107:
606:
496:and therefore increasing rate of
400:directly out of the cell and the
368:is brought about by a variety of
806:10.1111/j.1540-8159.2010.02838.x
740:Bulletin of Mathematical Biology
378:sarcoplasmic reticulum Ca-ATPase
200:type 2 ryanodine receptor (RyR2)
520:in the cell and so speeding up
402:Mitochondrial Ca Uniport system
296:. Ca binds to a protein called
276:. The two main myofilaments in
154:Calcium-induced calcium release
108:calcium induced calcium release
1045:10.1113/jphysiol.1994.sp020036
1001:
454:cyclic adenosine monophosphate
316:is known as a cross-bridge. A
168:transverse-tubules (t-tubules)
1:
542:
411:
234:, caused a larger release of
113:
322:adenosine triphosphate (ATP)
134:, can spontaneously produce
86:demands change. Ultimately,
7:
969:10.1529/biophysj.104.049973
624:World Journal of Cardiology
574:10.1016/j.yjmcc.2010.09.005
304:, to which the head of the
204:sarcoplasmic reticulum (SR)
118:Located in the wall of the
58:to be pumped, first to the
10:
1112:
904:10.1152/physrev.00037.2015
352:Termination of contraction
170:; which are also found in
144:cell membrane (sarcolemma)
106:during a process known as
1033:The Journal of Physiology
677:Marks, Andrew R. (2003).
396:, which uses ATP to pump
846:10.3389/fphys.2014.00082
484:). PKA affects both the
372:, known collectively as
162:penetrate deep into the
833:Frontiers in Physiology
500:. PKA also affects the
408:into the mitochondria.
332:then detaches from the
158:Certain regions of the
529:M2 muscarinic receptor
514:sarcoplasmic reticulum
384:back into the SR, the
260:
80:parasympathetic nerves
892:Physiological Reviews
637:10.4330/wjc.v7.i4.204
394:Sarcolemmal Ca-ATPase
257:
172:skeletal muscle cells
166:. These are known as
124:Sinoatrial node (SAN)
64:pulmonary circulation
68:systemic circulation
961:2004BpJ....87.3723H
949:Biophysical Journal
426:beta 1 adrenoceptor
186:are located on the
1016:on April 27, 2016.
752:10.1007/BF02458622
498:muscle contraction
442:cyclic AMP pathway
388:, which pumps one
274:muscle contraction
261:
250:Muscle Contraction
174:and allow for the
92:charged atom (ion)
90:revolves around a
88:muscle contraction
78:) or decrease it (
76:sympathetic nerves
800:(11): 1392–1406.
522:muscle relaxation
434:t-tubule membrane
428:) located in the
188:t-tubule membrane
142:travel along the
140:action potentials
136:action potentials
104:transverse tubule
82:), as the body's
1103:
1075:
1074:
1064:
1024:
1018:
1017:
1012:. Archived from
1005:
999:
998:
988:
955:(6): 3723–3736.
940:
934:
933:
923:
883:
877:
876:
866:
848:
824:
818:
817:
788:
782:
781:
771:
731:
725:
724:
714:
695:10.1172/JCI18067
674:
668:
667:
657:
639:
615:
604:
603:
593:
553:
478:protein kinase A
466:action potential
418:neurotransmitter
374:ion transporters
176:action potential
100:action potential
1111:
1110:
1106:
1105:
1104:
1102:
1101:
1100:
1096:Cardiac anatomy
1081:
1080:
1079:
1078:
1025:
1021:
1006:
1002:
941:
937:
884:
880:
825:
821:
789:
785:
732:
728:
675:
671:
616:
607:
554:
550:
545:
470:sinoatrial node
414:
354:
272:, resulting in
252:
156:
116:
12:
11:
5:
1109:
1099:
1098:
1093:
1077:
1076:
1039:(3): 447–462.
1019:
1000:
935:
898:(1): 227–252.
878:
819:
783:
726:
689:(5): 597–600.
669:
630:(4): 204–214.
605:
568:(6): 901–903.
547:
546:
544:
541:
456:). In the SAN
413:
410:
404:, which pumps
380:, which pumps
353:
350:
251:
248:
155:
152:
115:
112:
9:
6:
4:
3:
2:
1108:
1097:
1094:
1092:
1089:
1088:
1086:
1072:
1068:
1063:
1058:
1054:
1050:
1046:
1042:
1038:
1034:
1030:
1023:
1015:
1011:
1004:
996:
992:
987:
982:
978:
974:
970:
966:
962:
958:
954:
950:
946:
939:
931:
927:
922:
917:
913:
909:
905:
901:
897:
893:
889:
882:
874:
870:
865:
860:
856:
852:
847:
842:
838:
834:
830:
823:
815:
811:
807:
803:
799:
795:
787:
779:
775:
770:
765:
761:
757:
753:
749:
746:(1): 95–116.
745:
741:
737:
730:
722:
718:
713:
708:
704:
700:
696:
692:
688:
684:
680:
673:
665:
661:
656:
651:
647:
643:
638:
633:
629:
625:
621:
614:
612:
610:
601:
597:
592:
587:
583:
579:
575:
571:
567:
563:
559:
552:
548:
540:
538:
534:
530:
525:
523:
519:
515:
511:
510:phospholamban
507:
504:as well as a
503:
499:
495:
491:
487:
483:
479:
475:
471:
467:
463:
459:
455:
451:
447:
443:
439:
438:cardiac cells
435:
431:
427:
423:
422:noradrenaline
419:
409:
407:
403:
399:
395:
391:
387:
383:
379:
375:
371:
367:
363:
359:
349:
347:
343:
339:
335:
331:
327:
326:mitochondrion
323:
319:
315:
311:
307:
303:
299:
295:
291:
287:
283:
279:
275:
271:
267:
256:
247:
245:
241:
237:
233:
229:
228:calcium spark
225:
221:
217:
213:
209:
205:
201:
197:
193:
189:
185:
181:
177:
173:
169:
165:
161:
151:
149:
148:gap junctions
145:
141:
137:
133:
129:
125:
121:
111:
109:
105:
101:
97:
93:
89:
85:
81:
77:
73:
69:
65:
61:
57:
53:
52:heart muscles
49:
45:
41:
37:
33:
29:
25:
22:
18:
1036:
1032:
1022:
1014:the original
1003:
952:
948:
938:
895:
891:
881:
836:
832:
822:
797:
793:
786:
743:
739:
729:
686:
682:
672:
627:
623:
565:
561:
551:
526:
502:myofilaments
460:binds to an
415:
355:
270:myofilaments
262:
157:
120:right atrium
117:
96:calcium (Ca)
54:that allows
23:
20:
16:
15:
462:ion channel
364:within the
310:myosin head
238:within the
198:, called a
130:within the
48:contraction
32:contraction
24:EC coupling
1085:Categories
543:References
512:(PLB; see
430:sarcolemma
412:Heart rate
160:sarcolemma
114:Initiation
1053:0022-3751
977:0006-3495
912:0031-9333
855:1664-042X
760:0092-8240
703:0021-9738
646:1949-8462
582:1095-8584
533:G-protein
518:Cadecline
420:) called
320:, called
268:, called
222:into the
995:15465866
930:27881552
873:24578694
814:20946278
778:25665663
721:12618512
664:25914789
600:20850450
446:molecule
432:and the
370:proteins
318:molecule
298:troponin
282:skeletal
266:proteins
196:receptor
180:proteins
138:. These
1071:8014906
1062:1160336
986:1304886
957:Bibcode
921:6151489
864:3936571
769:4331357
655:4404375
591:3623268
508:called
506:protein
476:called
474:protein
448:called
278:cardiac
192:channel
182:called
50:of the
38:in the
36:muscles
30:to the
21:Cardiac
1069:
1059:
1051:
993:
983:
975:
928:
918:
910:
871:
861:
853:
839:: 82.
812:
776:
766:
758:
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712:151912
709:
701:
662:
652:
644:
598:
588:
580:
342:muscle
330:Myosin
306:myosin
294:myosin
286:muscle
206:. The
84:oxygen
72:nerves
1091:Heart
494:cells
468:(see
358:actin
338:actin
334:actin
314:actin
302:actin
290:actin
280:(and
259:site.
210:is a
132:heart
128:cells
60:lungs
56:blood
44:heart
40:heart
1067:PMID
1049:ISSN
991:PMID
973:ISSN
926:PMID
908:ISSN
869:PMID
851:ISSN
810:PMID
774:PMID
756:ISSN
717:PMID
699:ISSN
660:PMID
642:ISSN
596:PMID
578:ISSN
488:and
458:cAMP
450:cAMP
366:cell
292:and
288:are
240:cell
232:cell
224:cell
216:RyR2
164:cell
1057:PMC
1041:doi
1037:474
981:PMC
965:doi
916:PMC
900:doi
859:PMC
841:doi
802:doi
764:PMC
748:doi
707:PMC
691:doi
687:111
650:PMC
632:doi
586:PMC
570:doi
537:SAN
490:RyR
482:PKA
436:of
312:to
34:of
1087::
1065:.
1055:.
1047:.
1035:.
1031:.
989:.
979:.
971:.
963:.
953:87
951:.
947:.
924:.
914:.
906:.
896:97
894:.
890:.
867:.
857:.
849:.
835:.
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808:.
798:33
796:.
772:.
762:.
754:.
744:54
742:.
738:.
715:.
705:.
697:.
685:.
681:.
658:.
648:.
640:.
626:.
622:.
608:^
594:.
584:.
576:.
566:49
564:.
560:.
524:.
406:Ca
398:Ca
390:Ca
382:Ca
362:Ca
346:Ca
284:)
246:.
236:Ca
220:Ca
212:Ca
208:SR
150:.
110:.
94:,
1073:.
1043::
997:.
967::
959::
932:.
902::
875:.
843::
837:5
816:.
804::
780:.
750::
723:.
693::
666:.
634::
628:7
602:.
572::
480:(
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62:(
19:(
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