inhalation and expiration

• Normal Respiration- Inhalation :

  • The diaphragm (a dome-shaped muscle below the lungs) contracts and moves downwards.
  • The external intercostal muscles (muscles between the ribs) contract, lifting the ribs up and out.
  • The chest cavity expands, creating a lower pressure inside the lungs.
  • Air rushes into the lungs through the nose or mouth, the trachea, and the bronchial tubes.
  • The oxygen in the air is transferred to the bloodstream in the alveoli, where gas exchange occurs.
• Normal Respiration- Exhalation:

  • The diaphragm and external intercostal muscles relax.
  • The chest cavity becomes smaller, increasing the pressure inside the lungs.
  • Carbon dioxide, a waste product, is expelled from the bloodstream into the alveoli.
  • Air is forced out of the lungs and expelled through the nose or mouth.
• Laboured Respiration:

  Laboured respiration occurs when there is an increased demand for oxygen or when breathing becomes difficult due to certain factors such as illness or physical exertion.
• Inhalation - Laboured:

  • The exact process as normal inhalation occurs but with increased effort due to the body's higher oxygen demand.
  • Additional muscles, such as the neck and shoulder muscles, may be recruited to further expand the chest cavity.
• Exhalation (Breathing Out) - Laboured:

  • The exact process as normal exhalation occurs but with an increased effort to expel carbon dioxide from the lungs.
  • Laboured exhalation may require more forceful contraction of the abdominal muscles to help push the diaphragm upward and expel air.
• nerves involved:

  • The medulla oblongata contains the respiratory centre, which sends nerve signals to the muscles involved in breathing.
  • the phrenic nerve receives signals from the medulla, it contracts the diaphragm, causing it to move downward and increase the volume of the chest cavity.
  • signals goes through the intercostal nerves to the external intercostal: they contract and lift the ribs upward and outward, further expanding the chest cavity during inhalation.
• Involuntary Control:

  • Breathing is mostly involuntary, meaning we do not have to think about it consciously.
  • The medulla and associated nerves automatically adjust our breathing rate based on the body's needs.
• Chemical Control of Respiration -CO2 Levels:

  • When we breathe in oxygen, our cells use it for various functions and produce carbon dioxide as a waste product.
  • High levels of carbon dioxide in the blood trigger chemoreceptors in the brain, which send signals to increase our breathing rate.
  • This helps to remove excess carbon dioxide from the body and maintain a healthy balance of gases in the bloodstream.
• Chemical Control of Respiration - pH Levels:

  • The level of carbon dioxide is closely related to the acidity of our blood (pH).
  • When carbon dioxide levels increase, the blood becomes slightly more acidic.
  • Our body has a delicate pH balance, and if it becomes too acidic, it can harm our cells and organs.
  • To restore the proper pH balance, our breathing rate increases to remove excess carbon dioxide and reduce acidity.