03-06-12, 12:36 PM #1
Why is breathing both voluntary and involuntary?
How is the conscious control of breathing in our close cousins? How about further back to other mammals and reptiles? What is the evolutionary background to this dual control? And why only breathing when heart, digestion, etc are absolutely involuntary?
03-06-12, 12:48 PM #2
I don't know if this is true of all air-breathers (mammals and birds), but any animal that spends time in the water has to be able to control its breathing consciously.
This is so important that whales and the other cetaceans (who have no technique to keep their nostrils above water while sleeping, the way aquatic birds can) do not sleep like we do. They only shut down one brain hemisphere at a time, so the other one can continue to regulate breathing.
I wonder what kind of ritual they have when the sleeping hemisphere wakes up. Do the two furiously exchange information to "catch up"? Or does each hemisphere have a secret "private life"? Now that's what I call schizophrenia.
03-06-12, 12:55 PM #3
1. Because you always need to breathe.
2. Because sometimes you need to breathe more.
03-06-12, 12:57 PM #4
You can alter the heart rate with thought. For example, I can meditate to calm my heart and get it down to 60 beats per minute. I then start thinking about a sexy babe and get the heart to cycle quicker. Some yoga masters can get the heart to less than 10 bpm.
Breathing is easier is control. However, if you don't pay attention to it, it defaults back to normal rate. By controlling breathing we can alter the amount of terminal electron acceptor or the amount of oxygen in the body. If I hold my breath while exercising, I can cause a global change that will cause my muscles to build up lactic acid sooner. But I can also use this technique to cause my muscles to build up an anaerobic energy source, which I forget the name. This explosive energy can be induced by anaerobic training. Someone who does aerobic and makes use of plenty of O2 or terminal electron acceptor, may not have that same explosive energy since that anaerobic pathway is an alternate.
You can sort of control your digestive system too. As an example, some people are shy about going to the bathroom in front of others. This mental block can lead to constipation. Now the digestive system is altered. It is mind over matter. Sometimes it take a little reverse engineering or ingenuity to do what should not happen.
03-06-12, 01:08 PM #5
03-06-12, 01:31 PM #6
On the other hand, there is no benefit to having conscious control of heart rate and peristalsis - so there's no reason to evolve it.
03-06-12, 02:11 PM #7
Ans. to Thread Title? . . . . dual mode so that if we forget to breathe,
we don't die! Kind of like paying taxes, I'd guess (<--humor here)
Last edited by wlminex; 03-06-12 at 02:12 PM. Reason: Narrative
03-06-12, 03:07 PM #8
03-06-12, 03:12 PM #9
This is very useful, to have a way to calm down an agitated body/mind.
Although by affecting breathing, we affect the flow of energy through the body as a whole; so via breathing, we can affect the heartbeat etc.
03-06-12, 03:14 PM #10
03-06-12, 03:35 PM #11
03-06-12, 04:15 PM #12
swimming makes sense except for one thing, you can only conciously control your breathing for about 1 min. Try it, try conciously breathing for a extended period of time, you cant do it and its annoying anyway. Even when you swim certain breathing pattens are automatic, the mamalian diving reflex for instance which is what alows aquatic mamals to stay under water for so long and which also helps us (you can hold your breath longer under water than you can in air)
03-06-12, 05:55 PM #13
03-06-12, 07:23 PM #14
The question is interesting. I found the Wikipedia article interesting, too.
The best answer that I can say based on my experience in electronics is that the nervous control circuits are in two different places, rather parallel, up to some point where they somehow get spliced together before going on down to the diaphragm.
03-06-12, 07:54 PM #15
Minor illustrative value
In a broader sense I would suggest it is the evolutionarily advantageous arrangement. It allows greater flexibility in how one's body responds to demand.
To the other, imagine wars if people couldn't control their own breathing.
Extreme, I know, but hopefully of some minor illustrative value.
03-07-12, 01:01 AM #16
03-07-12, 04:37 AM #17
03-07-12, 07:45 AM #18
03-07-12, 08:51 PM #19
You don't have that level of control over your heartbeat. What you do is calm your mind, at the same time sending conscious signals to all your motor nerves to relax. Your heart senses a reduced need for blood so it slows down.
Your heart rate is controlled almost entirely by the concentration of CO2 in your blood. You have indirect control over that, which gives you an even more indirect ability to modify your pulse.Although by affecting breathing, we affect the flow of energy through the body as a whole; so via breathing, we can affect the heartbeat etc.
But if you mean controlling it in general, it's not true. Singers and musicians who play wind instruments have to have very disciplined control over their breathing in order to perform. Reed and horn players have developed a technique called circular breathing. They (well not all of them, just the experts) can continue exhaling into their mouthpiece for far longer than any human can hold his breath. They do it by slowly inflating their cheeks while blowing. Then they close off their glottis when it's time to breathe. There's enough air trapped in the cheeks to force it out between the lips and keep the instrument playing... yet meanwhile they are inhaling through their nose. Then when their lungs are full again they open the glottis and blow the regular way--once again slowly inflating the cheeks.
If this sounds impossible, it is an art that has to be mastered. Saxophonist Kenny G holds the Guinness record for circular breathing. He held an E-flat on his instrument for 45 minutes. Don't ask me what made him try that!
Native Australian didgeridoo players use circular breathing, as well as players of traditional instruments in other countries. It long predates modern Euro-American music.. . . . the mammalian diving reflex for instance which is what alows aquatic mamals to stay under water for so long and which also helps us (you can hold your breath longer under water than you can in air)
This is said to be a vestigial trait in humans that most people lose in their first year or two of life. Supposedly (I have not done any research into this, or even Snoped it) every now and then a baby sinks into the water and it takes five minutes or even longer before somebody spots him down there. They bring him up and discover that his heart is still beating even though he's deeply unconscious. They revive him and find that he's perfectly fine, although it takes a while to restore his body temperature to normal and to reactivate the circulation in his arms and legs.
03-07-12, 09:43 PM #20
FR no actually your wrong, circular breathing is a type of rhythm true but its no more a conscious deliberate control than breathing while swimming is. Its an automatic rhythm. However just for you I will check that in a couple of days when i see my brother, he is a tuba player so he knows how to use circular breathing. I'm not talking about holding your breath, do an experiment, while your doing the dishes or whatever boring task make yourself breath at a rate of 12-20 per min which is whats required to maintain life. Do this continuously and you wont find it comfortable. Why do you think we are taught that it doesn't matter if people know you want there respiratory rate past 1 min? because in the first 30 seconds or so they will maintain it consciously but pasted that it will fall back to automatic control.
And no, the mamalian diving reflex is present in ALL mamals including adult humans and it most certainly isn't a "vestigial trait". The Navy seals and there like are those who use it the most but everyone who swims uses it to an extent. Hold your breath and then swim around in the sea for a while, dive under and hold your breath for a while and see which is longer. Garentiee its under water because of the drop in heart rate vaso contriction etc. Children have the STRONGEST MDR but everyone has one.
Now you once told me that I shouldnt talk in your area of expertiees because i looked like an idiot and that you would stay out of mine. Well you look like an idiot when a simple wikipedia search will show your wrong.
The mammalian diving reflex is a reflex in mammals which optimizes respiration to allow staying underwater for extended periods of time. It is exhibited strongly in aquatic mammals (seals, otters, dolphins, etc.), but exists in a weaker version in other mammals, including humans. Diving birds, such as penguins, have a similar diving reflex. Every animal's diving reflex is triggered specifically by cold water contacting the face – water that is warmer than 21 °C (70 °F) does not cause the reflex, and neither does submersion of body parts other than the face. Also, the reflex is always exhibited more dramatically, and thus can grant longer survival, in young individuals.
Upon initiation of the reflex, three changes happen to a body, in this order:
1.Bradycardia is the first response to submersion. Immediately upon facial contact with cold water, the human heart rate slows down ten to twenty-five percent. Seals experience changes that are even more dramatic, going from about 125 beats per minute to as low as 10 on an extended dive. Slowing the heart rate lessens the need for bloodstream oxygen, leaving more to be used by other organs.
2.Next, peripheral vasoconstriction sets in. When under high pressure induced by deep diving, capillaries in the extremities start closing off, stopping blood circulation to those areas. Note that vasoconstriction usually applies to arterioles, but in this case is completely an effect of the capillaries. Toes and fingers close off first, then hands and feet, and ultimately arms and legs stop allowing blood circulation, leaving more blood for use by the heart and brain. Human musculature accounts for only 12% of the body's total oxygen storage, and the body's muscles tend to suffer cramping during this phase. Aquatic mammals have as much as 25 to 30% of their oxygen storage in muscle, and thus they can keep working long after capillary blood supply is stopped.
3.Finally is the blood shift that occurs only during very deep dives. When this happens, organ and circulatory walls allow plasma/water to pass freely throughout the thoracic cavity, so its pressure stays constant and the organs aren't crushed. In this stage, the lungs' alveoli fill up with blood plasma, which is reabsorbed when the animal leaves the pressurized environment. This stage of the diving reflex has been observed in humans (such as world champion freediver Martin Štěpánek) during extremely deep (over 90 metres or 300 ft) freedives.
Thus, both a conscious and an unconscious person can survive longer without oxygen under cold water than in a comparable situation on dry land. Children tend to survive longer than adults when deprived of oxygen underwater. The exact mechanism for this effect has been debated and may be a result of brain cooling similar to the protective effects seen in patients treated with deep hypothermia.
When the face is submerged, receptors that are sensitive to cold within the nasal cavity and other areas of the face supplied by cranial nerve V (trigeminal) relay the information to the brain and then innervate cranial nerve X, which is part of the autonomic nervous system. This causes bradycardia and peripheral vasoconstriction. Blood is removed from the limbs and all organs but the heart and the brain, creating a heart–brain circuit and allowing the mammal to conserve oxygen.
In humans, the mammalian diving reflex is not induced when limbs are introduced to cold water. Mild bradycardia is caused by subjects holding their breath without submerging the face within water. When breathing with face submerged this causes a diving reflex which increases proportionally to decreasing water temperature. Activating the diving reflex with cold water can be used to treat supraventricular tachycardia. However the greatest bradycardia effect is induced when the subject is holding breath with face submerged.
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