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    • #2950
      Phee
      Participant

      What actually causes us to start breathing, an increase in blood carbon dioxide levels or a decrease in blood oxygen levels?

    • #35204
      Poison
      Participant

      Aren’t they basically the same?

    • #35275
      MrMistery
      Participant

      He/She is asking what stimulates the pathway. I am rather curious myself since i did not come across this info anywhere…

    • #35349
      Poison
      Participant

      I couldn’t think of any logical explanation too.

    • #35358
      MrMistery
      Participant

      It is not a logic question, it is a question of cellular pathways and biochemistry

    • #35359
      Poison
      Participant

      yes, but increase of CO2 means decrease of O2. So which one stimulates…

    • #35387
      victor
      Participant

      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.

    • #35478
      MrMistery
      Participant

      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

    • #35485
      sdekivit
      Participant
      quote Poison:

      yes, but increase of CO2 means decrease of O2. So which one stimulates…

      the both regulate different things 😉

      –> High alveolar pCO2 cause bronchioles to dilate and high alveolar pO2 cause alveolar capillaries to dilate.

    • #35503
      Poison
      Participant

      I learned something new. 🙂 Good.
      But maybe the exact answer should be: both 😉

    • #35529
      victor
      Participant

      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..

    • #35540
      MrMistery
      Participant

      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?

    • #35579
      sdekivit
      Participant
      quote MrMistery:

      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?

      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.

    • #35584
      victor
      Participant

      wow..cool explanations..I’ll note that in my notebook..:mrgreen:

    • #35651
      Poison
      Participant

      I liked the explanation. 🙂

    • #35850
      kandarp shah
      Participant

      well,
      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.

    • #35960
      victor
      Participant

      Yup, that’s why you can’t kill yourself just by pressing your nose and hold your breath…it’s automatic…

    • #35993
      sdekivit
      Participant
      quote kandarp shah:

      well,
      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.

      and that these impulses can be influenced by a persons will and these impulses come from the cortex

    • #36089
      Navin
      Participant

      A fact: When a person is exposed to 100% oxygen, his/her breathing rate decreases.

    • #36100
      sdekivit
      Participant
      quote Navin:

      A fact: When a person is exposed to 100% oxygen, his/her breathing rate decreases.

      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 🙂

    • #36193
      MrMistery
      Participant

      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

    • #114460
      gardengirl7787
      Participant

      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.

    • #114474
      TYLS
      Participant

      i’m with victor on his guess about the pH having a role.

    • #114762
      zak
      Participant

      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.

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