What are the anatomical, physiological, and cellular mechanisms?

What are the physiological mechanisms responsible for changing tidal volume and respiration rate?

• What are the physiological mechanisms responsible for changing tidal volume and respiration rate after holding your breath

• Answer:

  These is no mechanism that changes tidal volume- that is done by increasing/decreasing the rate fo respiration. Respiration rate is controlled by respiratory centres in the pons and medulla of the mid brain, (the swelling at the top of the brain stem). It is related to the cardiovascular system too. The medulla recieves chemical, mechanical and hormonal signals and adjusts the rate of ventilation (breathing) by controlling the diaphragm and other respiratory muscles. Chemical receptors in the aortic arch and carotid bodies can sense elevated CO2 (hypercapnia) and send this information to the medulla which will increase ventilation rate. In quiet breathing inhalation occurs when your diaphragm contracts and moves down and your external intercostals move the ribcage up and out, these 2 actions increase the volume of the chest cavity, thus dropping the intrapleural (lung) pressure so air is sucked in. Exhalation is passive- ti si the elastic recoil of the diaphragm and external intercostals. Forced expiration (during exercise) is non-passive and involves the internal intercostal muscles contracting to force air out of the lungs. lastly standard ventilation for a minute (Ve) is number of breaths per minute* tidal volume: i.e. normal quiet breathing Ve = 12*500 = 6000ml or 6L/minute BUT DON'T FORGET DEAD SPACE dead space is usually 150 ml of the tidal volume therefore actual Ve = 12*350 = 4.2L/minute.