BPK 305 Lecture Notes - Lecture 24: Chronic Obstructive Pulmonary Disease, Macrophage, Lamellar Granule
5 Dec 2017
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Lecture 24 mechanical properties of the lungs i. Innervation of muscles muscles: expiratory muscles are innervated between t1-t12 of the spinal cord, lower down in the spine. Inspiratory muscles: lateral external intercostals -> t1-t12, scm -> c1-c2, diaphragm -> c3-c5. Innervated much higher up in the spine: spinal cord injury above t12 will influence respiratory function (ex. during exercise) Injury above c5 renders inspiration dependent on accessory muscles. Lungs are highly distensible (100x more than a balloon) Compliance (distensibility) refers to ease with which lungs can expand under pressure. Determined by elastin and collagen fibers in lung parenchyma. Lung inflation elongates these fibers, exerting more elastic force = elastic recoil so lungs revert to initial size following distention. Elastic recoil is the reason lungs collapse with a pneumothorax. Decreased compliance = increased resistance to distention (ex. pulmonary fibrosis) Measured under static conditions (glottis open, no air flow, so pa = 0)
