Biology Forum › Human Biology › How does the heart work?
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- January 21, 2006 at 12:31 am #3294
angeloParticipantHow does the heart work? I mean, is every beat mediated by an electrical signal from the brain? If so (or not) , where does the signal originate? What creates it, and what keeps it from stopping? (How could it be so robust?)
- January 21, 2006 at 3:13 am #37944pratisthaParticipant
our heart is called myogenic heart because wave of contraction starts from heart itself.there is sinu auricular node at the top of right auricle which is a small island of tissues.it starts the wave.it is also called as pace maker.the wave is picked by atrioventricular node present in between right and left auricle. it is divided in 2 branches witheach having sub branches called purkinje fibres.these help heart do its work
- January 21, 2006 at 10:03 pm #38016angeloParticipant
Ok (thanks). So I suppose that the chemical properties of cells in the SA node and their enviroment are generating action potentials in the cells. But what makes them fire so slowly, and in such a rythmic manner?
- January 22, 2006 at 8:36 am #38050sdekivitParticipantquote angelo:Ok (thanks). So I suppose that the chemical properties of cells in the SA node and their enviroment are generating action potentials in the cells. But what makes them fire so slowly, and in such a rythmic manner?
yes, they have so called If-Ca(2+)-channels which depolarize when e membrane potential of -60 mV is reached, resulting in contraction cycles.
- January 22, 2006 at 11:55 am #38064jnkdnaParticipant
hey is auricle and atrium the same?
just wanted to be sure 😀 - January 22, 2006 at 12:06 pm #38070opuntiaParticipant
No they are not same, auricle is a small conical pouch projecting from the upper anterior part of each atrium of the heart and you know what atrium is.
- January 22, 2006 at 12:27 pm #38079Dr.SteinParticipant
The heartbeat is initiated by the pacemaker 🙂
- January 22, 2006 at 12:39 pm #38089opuntiaParticipant
In other words it’s the Sinoatrial Node that originates the excitation…isn’t it?
- January 22, 2006 at 2:45 pm #38131angeloParticipantquote :yes, they have so called If-Ca(2+)-channels which depolarize when e membrane potential of -60 mV is reached, resulting in contraction cycles.
Ok. So at the time of action potential, the Ca(2+) channels are letting calcium flow into the cell. The refractory period is relatively long. Why is it so long?
- January 22, 2006 at 9:37 pm #38156jnkdnaParticipantquote opuntia:In other words it’s the Sinoatrial Node that originates the excitation…isn’t it?
yeah i think it is! i just studied it yesterday! 8)
- January 23, 2006 at 1:22 pm #38197sdekivitParticipantquote angelo:quote :yes, they have so called If-Ca(2+)-channels which depolarize when e membrane potential of -60 mV is reached, resulting in contraction cycles.
Ok. So at the time of action potential, the Ca(2+) channels are letting calcium flow into the cell. The refractory period is relatively long. Why is it so long?
the pacemaker actionpotential is way shorter than the cardiac actionpotential (plateauphase and initiation by Na-influx). The pacemaker actionpotential doesn’t rely on Na-ions.
- January 24, 2006 at 7:04 am #38286Dr.SteinParticipant
I like the term "all or none" in this topic 🙂
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