December 18, 2005 at 8:55 pm #2950PheeParticipant
What actually causes us to start breathing, an increase in blood carbon dioxide levels or a decrease in blood oxygen levels?
December 19, 2005 at 9:28 pm #35204
Aren’t they basically the same?
December 20, 2005 at 7:30 pm #35275
He/She is asking what stimulates the pathway. I am rather curious myself since i did not come across this info anywhere…
December 21, 2005 at 8:22 pm #35349
I couldn’t think of any logical explanation too.
December 21, 2005 at 9:02 pm #35358
It is not a logic question, it is a question of cellular pathways and biochemistry
December 21, 2005 at 9:29 pm #35359
yes, but increase of CO2 means decrease of O2. So which one stimulates…
December 22, 2005 at 11:50 am #35387
breathing is under the control of autonom nerve. When the cells and Tissues lack of oxygen, they send a chemical signals to the nervous system and ‘autonom’ically, we’re forced to take a breath.
Beside, there’re also many other factors which get involved in this mechanism like inhibotors, pH, CO2-O2 equilibrium, etc.
December 24, 2005 at 4:39 pm #35478
That is what the user is asking, a very interesting question: What stimulates that nerve impulse? Excess CO2 or/and lack of O2? Of course they happen at the same time but which one works as a stimulus? My guess is just like yours victor: lack of O2. However, i have no reference to prove my theory
December 24, 2005 at 5:32 pm #35485quote Poison:
the both regulate different things 😉
–> High alveolar pCO2 cause bronchioles to dilate and high alveolar pO2 cause alveolar capillaries to dilate.
December 24, 2005 at 8:09 pm #35503
I learned something new. 🙂 Good.
But maybe the exact answer should be: both 😉
December 25, 2005 at 12:00 pm #35529
My hypothesis said that it’s related with the pH of the interestial fluid..excess of CO2 means little bit acidic blood plasm and I can think that’s the time when signals should be transducted..
December 25, 2005 at 4:26 pm #35540
LOL… I understood the question in a different way. When you hold your breath, what is the thing that gets your breathing muscles started? Is it excess CO2 or a lack of oxygen?
December 26, 2005 at 12:11 pm #35579quote MrMistery:
it’s the hypoxia in the brains that a person loses its conciousness and then the breathing muscles are stimulated both by too high pCO2 and too low pO2 via the peripheral and central chemoreceptors.
Note that the cortical impulses of the brain are involved in willingly holding ones breath.
But most of the time it’s the pCO2 and the pH that give THE impulses to the medulla, because peripheral chemoreceptors only respond to an oxygen level below the 60 mmHg.
December 26, 2005 at 12:40 pm #35584
wow..cool explanations..I’ll note that in my notebook..:mrgreen:
December 27, 2005 at 7:13 am #35651
I liked the explanation. 🙂
December 30, 2005 at 4:59 pm #35850kandarp shahParticipant
i just know that breathing and all other automatic process that take place in our body are handle by the BRAIN STEM, the bundle of neurons that connects the two cerebellum hemisphere.
January 1, 2006 at 12:00 pm #35960
Yup, that’s why you can’t kill yourself just by pressing your nose and hold your breath…it’s automatic…
January 1, 2006 at 10:01 pm #35993quote kandarp shah:
and that these impulses can be influenced by a persons will and these impulses come from the cortex
January 3, 2006 at 1:32 pm #36089NavinParticipant
A fact: When a person is exposed to 100% oxygen, his/her breathing rate decreases.
January 3, 2006 at 5:48 pm #36100quote Navin:
of course it does 😉 100% O2 causes a decrease in pCO2 and thus less firing of the chemoreceptors and thus a less sympathetic innervation of the breathing muscles 🙂
January 4, 2006 at 9:06 pm #36193
it is logical for it to decrease. think of it like this: 100 O2 will have a greater pressure than air, meaning more oxygen is transported, meaning it is not necessary for the heart to pump blood as fast as it used to. Mechanism stated by sdekivit
October 6, 2013 at 9:58 pm #114460gardengirl7787Participant
Healthy persons breathe because of the increase of CO2 levels-which is the stimulus.
A person with COPD for example breathes when the O2 level gets too low, so it is important to monitor how much oxygen (if any) the person is on closely. Too much O2 can cause the drive to breathe to stop.
October 10, 2013 at 2:29 pm #114474TYLSParticipant
i’m with victor on his guess about the pH having a role.
November 21, 2013 at 10:20 am #114762zakParticipant
i need help plz i did it in this way is that correct
Consider the causes of left-sided heart failure:
Choose one phrase from those available to correctly accompany, each of the factors a-e.
Drag and drop the phrase into the appropriate box. Each phrase may only be used once.
a. Breathlessness (reduces the oxygen carrying capacity of the blood)
b. An overactive thyroid gland (increases the metabolic demand by the tissues.)
c. Stenosis of the mitral valve (causes damage to heart muscle.)
d. Diabetes (is associated with weight gain )
e. Calcification of the tricuspid valve (reduces the left cardiac output. )
shunts unoxygenated blood directly from the right to the left side of the circulation.
causes regurgitation between atrium and ventricle.
reduces the oxygen carrying capacity of the blood.
is a symptom, not a cause.
is not associated with left sided heart failure.
is associated with weight gain
increases the metabolic demand by the tissues.
causes damage to heart muscle.
reduces the left cardiac output.
- You must be logged in to reply to this topic.