The Naked Scientists

The Naked Scientists Forum

Author Topic: Why would two hearts be better than one?  (Read 7927 times)

Offline Make it Lady

  • Neilep Level Member
  • ******
  • Posts: 4050
  • Hands-on fun for everyone!
    • View Profile
Why would two hearts be better than one?
« on: 24/02/2008 22:09:36 »
Why would Doctor Who, the Fictional time traveller, evolve to have two hearts? What would he use them for and how would they work. My son asked me and I'm not a Biologist. Anyone got any good theories? 


 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Why would two hearts be better than one?
« Reply #1 on: 24/02/2008 22:26:56 »
1) 2 doing the work of 1, they wouldn't wear out so fast.
2) In case he gets heart-broken.
3) So he can cheat at whist.
4) His creator mis-heard the saying "2 heads are better than 1"
 

Offline Karen W.

  • Moderator
  • Naked Science Forum GOD!
  • *****
  • Posts: 31653
  • Thanked: 5 times
  • "come fly with me"
    • View Profile
Why would two hearts be better than one?
« Reply #2 on: 24/02/2008 22:37:44 »
Perhaps as a backup in case the first explodes.... ie like doc said in case 1 gets broken!

Or perhaps the next time he latches on to a lightening rod when the first one stops the second one kicks in after the shock stops! LOL!

Perhaps it allows more blood flow to the brain and other organs and enhances mental or intellectual capacity providing more oxygenated blood to reach the brain? Hee hee.. I love that show!
« Last Edit: 24/02/2008 22:39:29 by Karen W. »
 

another_someone

  • Guest
Why would two hearts be better than one?
« Reply #3 on: 25/02/2008 01:15:21 »
It really depends on how the hearts are configured.

In a sense humans actually have two hearts, but the two hearts are closely bound, and form two sides of a single heart.  We have the arrangement so we can separate the pulmonary blood supply (to the lungs) from the blood supply to the rest of the body.

It is conceivable that the two halves of our heart could be separated, so providing the same functionality that our heart does in supplying two separate blood flows.  It is also possible that the Doctor's blood flow is even more divided, so having 4 halves, and two complete hearts.

One problem I can see with subdividing the heart into separate units is to maintain a balance in the pressure between the different blood supplies; but it is possible that this could be maintained by nerve signals of a hormone system that tries to keep the hearts synchronised so as to avoid all the blood being drawn out of one system and pushed into another.

Another possibility would be a complete dual 'blood' supply system throughout the body.  I placed the word 'blood' in quotes, since having two supply systems would probably imply that they performed subtly different functions, and may be pumping different fluids around the body, possibly neither of them directly correlating with 'blood' as we would understand it (maybe in part it could perform some of the functions of the lymphatic system in animals/humans).

What is extremely unlikely is that the two hearts would be operating, either in series or in parallel, to drive the same blood supply, since anything but the most careful synchronisation of the beats could cause one heart to interfere with the performance of the other heart.
 

Offline Simulated

  • Neilep Level Member
  • ******
  • Posts: 7188
  • Thanked: 1 times
  • Simulated..What more do you needa know :P
    • View Profile
    • Facebook
Why would two hearts be better than one?
« Reply #4 on: 25/02/2008 01:17:31 »
I'd have to say two wouldn't be better because its just one more thing that could go wrong and kill you :) ha
 

Offline Karen W.

  • Moderator
  • Naked Science Forum GOD!
  • *****
  • Posts: 31653
  • Thanked: 5 times
  • "come fly with me"
    • View Profile
Why would two hearts be better than one?
« Reply #5 on: 25/02/2008 01:28:46 »
could go right and save you too! ha!
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • Posts: 12656
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Why would two hearts be better than one?
« Reply #6 on: 25/02/2008 08:03:33 »
I'd have to say two wouldn't be better because its just one more thing that could go wrong and kill you :) ha

Following that logic, we shouldn't have any organs at all.
 

Offline MayoFlyFarmer

  • Hero Member
  • *****
  • Posts: 863
    • View Profile
    • http://www.myspace.com/wiguyinmn
Why would two hearts be better than one?
« Reply #7 on: 25/02/2008 17:07:16 »
don't know too much about doctor who, but the easiest logic would be Dr. Beaver's #1, that two hearts pumping in paralell (if you think of the circulatory system like an electrical circuit) means that each heart would have to do half the work an ordinary heat does and thus not wear out as fast.  Getting back to the electrical circut analogy, if you have two light bulbs in parralell, they put out as much light as one light bulb in a simple circuit, but they last twice as long as the single light bulb would.
 

Offline Make it Lady

  • Neilep Level Member
  • ******
  • Posts: 4050
  • Hands-on fun for everyone!
    • View Profile
Why would two hearts be better than one?
« Reply #8 on: 25/02/2008 17:43:51 »
I asked a friend this question today and they thought that it must be to do with all the energy the doctor uses up. He is supposed to be like a power plant of energy.

They also thought that because the program involves lots of running perhaps one heart feeds his muscles so that he can run far and fast and the other feeds things like his digestive system which is often impaired in marathon runners towards the end of a run.

I'm not a biologist but I do understand that the two sides of the heart are not housed separately because of keeping the beats in sink.
 

another_someone

  • Guest
Why would two hearts be better than one?
« Reply #9 on: 25/02/2008 22:14:22 »
don't know too much about doctor who, but the easiest logic would be Dr. Beaver's #1, that two hearts pumping in paralell (if you think of the circulatory system like an electrical circuit) means that each heart would have to do half the work an ordinary heat does and thus not wear out as fast.  Getting back to the electrical circut analogy, if you have two light bulbs in parralell, they put out as much light as one light bulb in a simple circuit, but they last twice as long as the single light bulb would.

It is not really about having two light bulbs (which is analogous to having two kidneys), but more like having two electrical power sources in parallel.  If the two power sources are DC power sources, then it is easy to do, and two are better than one.  The problem is that if you have two AC power sources (analogues to a beating heart), then if the two power supplies are not in phase with each other, then you will have massive inefficiencies as the the current travelling between the two power sources absorbs a lot of energy that might otherwise to pumped into the external circuit.
 

Offline iko

  • Neilep Level Member
  • ******
  • Posts: 1626
  • Thanked: 1 times
    • View Profile
Why would two hearts be better than one?
« Reply #10 on: 25/02/2008 23:08:38 »
It is not really about having two light bulbs (which is analogous to having two kidneys), but more like having two electrical power sources in parallel.  If the two power sources are DC power sources, then it is easy to do, and two are better than one.  The problem is that if you have two AC power sources (analogues to a beating heart), then if the two power supplies are not in phase with each other, then you will have massive inefficiencies as the the current travelling between the two power sources absorbs a lot of energy that might otherwise to pumped into the external circuit.

Hi another_someone,

there might be problems of space to fit two hearts, and 'phasing' troubles too...
Artificial hearts are currently used to assist circulation in the left ventricle:



...you can have a look at ScienceDaily for  more details:

« Last Edit: 25/02/2008 23:15:48 by iko »
 

Offline Make it Lady

  • Neilep Level Member
  • ******
  • Posts: 4050
  • Hands-on fun for everyone!
    • View Profile
Why would two hearts be better than one?
« Reply #11 on: 26/02/2008 22:48:48 »
Iko that was really good. What do you think about my marathon runner idea?
 

another_someone

  • Guest
Why would two hearts be better than one?
« Reply #12 on: 26/02/2008 23:51:30 »
Looking both at the diagram, and the wiki entries, it states that the majority of VADs are continuous flow devices (although 3 pulsating devices have been approved).  Continuous flow pumps would not have the phasing problems of pulsating devices (although apparently they have other problems with bearings).  In animal structures, I don't know of any organ that is capable of continuous rotation in the way that an axial or centrifugal pump would deliver a continuous flow.

Also, the diagram (and I would expect the reality) shows the VAD to be in close proximity to the real heart, and I would imagine that the short pipework would also contribute to reduced possibility for crossflow between the artificial and real organ.  As I already suggested, it may be suggested that we actually already have two pumps in our chest, but they are integrated into the two halves of a single device, so improving co-ordination between the two pumping actions.

I assume that the reference in Dr. Who to two hearts, it refers to two separate organs, rather than merely doubling in the number of pumping systems integrated into a single heart.
« Last Edit: 26/02/2008 23:57:02 by another_someone »
 

Offline RD

  • Neilep Level Member
  • ******
  • Posts: 8128
  • Thanked: 53 times
    • View Profile
Why would two hearts be better than one?
« Reply #13 on: 28/02/2008 11:52:10 »
Quote
Octopuses have three hearts. Two pump blood through each of the two gills, while the third pumps blood through the body.
http://en.wikipedia.org/wiki/Octopus

 

another_someone

  • Guest
Why would two hearts be better than one?
« Reply #14 on: 28/02/2008 12:13:17 »
Quote
Octopuses have three hearts. Two pump blood through each of the two gills, while the third pumps blood through the body.
http://en.wikipedia.org/wiki/Octopus

But again, like the two separate parts of our heart, they are supplying separate subsystems of the blood circulatory system, rather than simply parallel running on the same system (which is the possibility I allowed for earlier).
 

Offline Make it Lady

  • Neilep Level Member
  • ******
  • Posts: 4050
  • Hands-on fun for everyone!
    • View Profile
Why would two hearts be better than one?
« Reply #15 on: 28/02/2008 14:53:01 »
Firstly Doctor Who does have two separate organs (lucky man) and secondly I think the octopus idea is probably the one I'd plump for. Has anyone seen any episodes that prove the doctors hearts run in parallel. I think they would look after separate systems. I seems sensible to me.
 

The Naked Scientists Forum

Why would two hearts be better than one?
« Reply #15 on: 28/02/2008 14:53:01 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums