UNIT 3: Muscles of Respiration Flashcards
(89 cards)
what is pressure?
force exerted on walls of a chamber by gas molecules
at rest what is the pressure inside the thoracic cavity the same as?
atmospheric pressure
pressure = ____/_____, therefore…
force over area, as area inc pressure dec, as area dec pressure inc
positive pressure in the thoracic chamber means it is ___ than atmospheric pressure
greater
negative pressure in the thoracic chamber means it is ___ than atmospheric pressure
less
according to boyle’s law, increasing the volume of the thorax/lungs and will ___and will lead to …
dec intrathoracic pressure, air being drawn into the lungs (to equalize pressure w atmosphere)
according to boyle’s law, decreasing the volume of the thorax/lungs and will ____ ___and will lead to …
inc intrathoracic pressure, air will move out of the lungs (to equalize w atmosphere)
what are the 3 planes of thoracic volume change?
vertical
transverse (bucket handle)
anterior-posterior (pump handle)
describe vertical thoracic volume change
- inc primarily due to contraction of the diaphragm
- elevation of manubrium and 1st rib may also inc vertical dimension
describe transverse thoracic volume change
- “bucket handle” - up and out
- inc w elevation of ribs afforded by accessory muscles
describe anterior-posterior thoracic volume change
- “pump handle”
- inc w elevation of ribs via accessory muscles
what are the 2 types of inspiration?
quiet (rest) and forced (inc oxygen needs)
quiet inspiration (active passive?, muscles?)
- requires muscle activation
- diaphragm is most important, does most of the work of quiet inspiration
forced inspiration (active passive?, muscles?)
- requires muscle activation
- accessory muscles
two types of expiration
quiet expiration, forced expiration
quiet expiration (active passive?, muscles?)
- involves passive forces only (no active forces)
- gravity pulls ribs back to rest
- elasticity: when lungs are stretched by inc thoracic volume they will return to original shape and size when released
forced expiration (active passive?, muscles?)
requires muscles activation + passive forces
how many attachment points do skeletal muscles often have?
2
muscle fibres pull ___ their origin, moving the ____ point closer to the _____
toward, insertion, origin
what are the 3 primary muscles of inspiration
- diaphragm
- external intercostals
- interchondral portion of internal intercostals
describe the diaphragm
- only unpaired muscle of respiration
- separates thoracic and abdominal cavities
- participates in quiet inspiration and forced inspiration
- contraction inc volume of thorax in vertical dimension
where does the diaphragm attach?
vertebrae via crura (right crus and left crus)
what is the central tendon of the diaphragm?
- leaf shaped aponeurosis
- striated muscle fibers that surround central tendon
- provides floor for mediastinal organ
- compresses abdominal structures cyclically during respiration
what are the 3 hiatuses of the diaphragm?
- aortic hiatus
- esophageal hiatus
- foramen vena cava