breathing Flashcards
what type of process in exhalation
-passive (external intercostal)
-active (internal intercostal)
what happens during exhalation
-external intercostals relax
-rib cage moves down and inwards
-diaphragm relaxes and arches upwards
-volume in thorax decreases
-pressure in thorax increases (above atmospheric)
what is the upwards movement of the diaphragm caused by in exhalation
pushed up by displaced organs below
what happens during inhalation
-external intercostals contract and pull upwards (internal n/a)
-rib cage moves up and outwards
-diaphragm moves downwards and flattens
-volume in thorax increases
-pressure in thorax decreases (below atmospheric)
-air moves in down a conc grad
what does the diaphragm do as it moves downwards and flattens
displaces digestive organs downwards
why is exhalation passive
-caused by natural recoil of elastic fibres in lung tissue
what is the movement of air into/out of the lungs caused by
pressure changes in the thorax
what do internal intercostal muscles assist
-assist the external intercostal muscles with exhalation
how do internal intercostal muscles assist external ones
-during exhalation external muscles relax
-internal muscles can contract to help push air out forcefully
what happens during coughing
-internal intercostals contract pulling rib down hard and fast
-abdominal muscles contract, forcing diaphragm up
what 2 things cause recoil in alveoli
-elastin in elastic fibres of connective tissue
-moist lining in the alveoli
what is surfactant
a secretion in alveoli that has water in it
how does moist lining cause recoil
-water molecules in moist lining pull together
-due to polarity and hydrogen bonding they pull on alveoli walls causing them to recoil and get smaller
what is total collapse of alveoli prevented by
-moist lining
-intrapleural pressure
role of surfactant
-produced by lungs
-reduce cohesive forces between water molecules to lower surface tension
-prevent alveoli collapse
