PSL301H1 Lecture Notes - Lecture 17: Cystic Fibrosis, Phrenic Nerve, Rib Cage
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PSL301H1 Full Course Notes
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Defect in the cftr protein should normally transport cl- out of the cell; another channel (enac) brings in na+ ions to balance out the net charge; water also comes into the cell. Cl- ions accumulate inside the cell; to compensate, more sodium goes into the cell. Due to more ions inside the cell, more water is drawn into the cell. Mucus should be eliminated (since it is fluid); since it is too sticky, pathogens accumulate and are not eliminated. Epithelial cells become damaged chronic damage leads to fibrosis. Lungs have difficulty expanding and we have issues with gas exchange. Two phrenic nerves innervates the diaphragm (most important muscle) Diaphragm contracts and goes down this allows the thoracic volume to increase & lungs expand (ie. forms negative pressure inside the lungs, allowing air to go in) Passive expiration elastic recoil; we return to the normal position, pushing air outside the lungs. Certain conditions contract abdominal muscles to release more air (review)
