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Lec.10 mechanics of resp


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Anatomy course for Physical therapy and Respiratory care under-graduate students

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Lec.10 mechanics of resp

  1. 1. College of Medicine Mechanics MMMeeeccchhhaaannniiicccsss ooooffff RRRReeeessssppppiiiirrrraaaattttiiiioooonnnn Respiration occurs in a cyclic manner; respiratory cycle. The Respiratory Cycle consists of: Normal respiratory rate in adults is 16 children, and slower in elderly. In inspiration, the capacity of the thoracic cage is increased by increasing the: a) Vertical diameter: • By lowering the diaphragm. • The suprapleural membrane is constant b) Anteroposterior diameter: • By pushing the sternum anteriorly v Handle Mechanism) • This takes place mainly in the upper 7 ribs c) Transverse diameter: • By the Bucket Handle Mechanism • This takes place mainly in the lower ribs So, normal quite inspiration is an active process (intercostals and diaphragm) Anatomy Dept. MMMMeeeecccchhhhaaaannnniiiiccccssss A) Inspiration B) Expiration C) pause 16-20 cycle per minute. It is faster in infants and A) Inspiration: via raising the twisted ribs Mechanism). Mechanism. that needs contraction of muscles Anatomy (1) for PT & RC Dr. Kamal Motawei 1 . ia (Pump
  2. 2. Anatomy Dept. Anatomy (1) for PT & RC College of Medicine Dr. Kamal Motawei 2 In deep and forced inspiration: Additional muscles are called into action. These are the accessory muscles of respiration namely: pectoralis major, pectoralis minor, serratus anterior serratus posterior superior. Fixing the upper limbs (e.g. by holding a chair-back) will make these muscles raise the ribs and helps in inspiration. Lung Changes in inspiration: 1- Roots of the lungs descend. 2- Level of the bifurcation of the trachea descends two vertebrae (from T4 to T6) 3- Bronchi, alveoli and capillaries dilate. 4- The lower margin of the lung occupies the costodiaphragmatic recess. 5- Pulmonary circulation is increased.
  3. 3. Anatomy Dept. Anatomy (1) for PT RC College of Medicine Dr. Kamal Motawei 3 A) Expiration: Quite expiration: It is a passive process, it occurs as a result of relaxation of the inspiratory muscles and elastic recoil of the lungs. It is associated with increased tone of the abdominal muscles to push the diaphragm up. So, all the thoracic diameters are reduced again. Forced expiration: It is an active process that need contraction of muscles namely, anterior abdominal wall muscles and quadrates lumborum. The 12th rib is fixed by the quadrates lumborum , so contraction of the intercostals leads to lowering down of the ribs The neck is flexed anteriorly to make the fist rib more malleable. Lung changes in expiration: 1- Roots of the lungs and bifurcation of the trachea ascend. 2- Elastic recoil of the lungs. 3- Lower border of the lung rises up and get out of the costodiaphragmatic recess. Types of respiration: A) Abdominal respiration: • Depends mainly on the diaphragm • Occurs mainly in children less than 2yrs old. • Also, in adult men respiration is mainly abdominal. B) Thoracic respiration: • Depends mainly on the intercostal muscles • Occurs mainly in adult women.