observe the movement of your stomach during inhalation and exhalation.what can be the reason behind your observation
Answers
Answer:Normal ventilation is an automatic, seemingly effortless inspiratory expansion and expiratory contraction of the chest cage. This act of normal breathing has a relatively constant rate and inspiratory volume that together constitute normal respiratory rhythm. The accessory muscles of inspiration (sternocleidomastoid and scalenes) and expiration (abdominal) are not normally used in the resting state. Abnormalities may occur in rate, rhythm, and in the effort of breathing.
Technique
The establishment of the tidal volume and pattern of respiration in normal individuals is a complicated process. Recognizing alterations in these factors is an important early clue of disease recognition. While frequently it is nonspecific, in many instances it can lead directly to a diagnosis. Careful observation of the respiratory rate and pattern is a crucial part of the physical examination.
Simple inspection of the respiratory cycle, observing rate, rhythm, inspiratory volume, and effort of breathing, is all that is necessary. The rate is noted by observing the frequency of the inspiratory phase, since this phase is active and easy to count. Record the number of breaths per minute; this is the respiratory rate. While observing the rate, note the inspiratory expansion of the chest cage. This expansion should be the same during each cycle.
Normally, the accessory muscles of inspiration and expiration are not used. Their use should be observed and, if found, recorded as "use of accessory muscles on inspiration" and "expiration is active with abdominal muscle contraction."
Basic Science
The respiratory system's major functions are to provide an adequate oxygen (O2) supply to meet the energy production requirements of the body and maintain a suitable acid-base status by removing carbon dioxide (CO2) from the body. This is accomplished by moving varying volumes of air into and out of the lungs. Ventilation, the process of air movement into the lungs, is a carefully controlled modality with a wide range of response that enables the markers of gas exchange adequacy (Pao2, Paco2, and pH) to be kept within a relatively small physiologic range.
To maintain accurate control the respiratory system has a central respiratory pacemaker located within the medulla of the brainstem. Neural output travels from this center through the spinal cord to the muscles of respiration. The changes are effected through two groups of muscles, inspiratory and expiratory, which contract and relax to produce a rhythmic respiratory rate and pattern. In most individuals with unchanging metabolic demand, the rate and pattern are surprisingly constant, only interrupted every several minutes by a larger inspiratory effort or sigh. Ventilation at rest in most individuals requires only the inspiratory muscles. Expiration is usually passive and is secondary to the respiratory system returning to its resting state. Therefore, with quiet breathing the inspiratory time is the period of active respiratory pacemaker output. Adjusting the rate, length, and intensity of neural output from the pacemaker will lead to changes in the breaths per minute and the volume of each inspiration or tidal volume. These final outputs of the respiratory pacemaker, the rate and tidal volume, are the two components of ventilation. The expiratory muscles begin to play a role with disease or increased ventilatory demands. When this occurs, the length of time it takes to empty the lungs adequately will also lead to changes in rate and tidal volume.