mammalian ventilation Flashcards
outline the path that air takes as it is inhaled
nasal passage - trachea - bronchi - bronchioles - alveoli
Now They Breathe Big ‘Ah’s
3 adaptations + functions of the nasal passage
- rich blood supply warms air as it enters nose
- hairy lining + mucus secretion traps dust and pathogens
- moist surface so air is humid, also prevents water loss in alveoli
2 adaptations + functions of trachea
- C shaped rings of cartilage ensure air channel is always open, as it is able to bend when swallowing food, also provides support
- lined with ciliated epithelial cells + goblet cells which prevent dust and pathogens from entering body
outline the structure of the bronchi
these are extensions of the trachea that split into 2 for the left and right lung
they have similar structures to the trachea only smaller
2 adaptations + functions of bronchioles
- diameter is <1mm so short diffusion distance
- lined with a thin layer of squamous epithelial cells that facilitated gas exchange as there is a short diffusion distance - this is the first point where gas can be exchanged
7 adaptations + functions of alveoli which make it an efficient exchange surface
- alveoli walls are made of 1 layer of squamous epithelial cells which decreases diffusion distance
- walls also contain collagen + elastic fibres allowing alveoli to recoil, helping air move out of sacs
- lungs contain many alveoli so high SA:V, large SA for O2 to diffuse across which increases diffusion rate
- rich blood supply due to extensive capillary network, blood here has a high [CO2] and a low [O2], concentration gradient increases rate of diffusion - CO2 can diffuse out of blood to be exhaled
- ventilation from breathing also maintains concentration gradient
- moist walls allow gases to dissolve so they can diffuse quickly
- alveoli are coated in liquid surfactant which lowers surface tension at air/liquid interface, ensuring alveoli doesn’t collapse, as well as killing pathogens + preventing them from entering lungs
what are alveoli
little sacs of air where most gas exchange occurs
diameter is 200-300 micrometers
why are respiratory infections so common
alveoli + lungs are warm, moist environments with high [O2] and rich blood supplies, which is a prime environment for bacteria
what occurs during inspiration
- diaphragm moves down
- intercostal muscles contract and ribs move up + out
- thoracic volume increases so thoracic pressure decreases
- air flows into lungs to equalise pressure difference between air outside lungs and inside lungs
what occurs during expiration
- diaphragm moves up
- intercostal muscles relax and ribs move down + in
- thoracic volume decreases so thoracic pressure increases
- air flows out of lungs to equalise pressure difference between air inside lungs and air outside lungs
ventilation rate definition + calculation
the total amount of air moved into the lungs in 1 minute
tidal volume x breathing rate
total lung capacity =
residual volume + vital capacity
residual volume definition
the volume that stays in lungs after forced exhalation
vital capacity definition
the volume of air exchanged between maximum and minimum inspiration
vital capacity =
inspiratory reserve volume + expiratory reserve volume + tidal volume
tidal volume definition
volume breathed in and out in a single breath
what is a spirometer
these measure the volume and speed of a gas breathed in and out of the lungs
- they can be used to assess asthma, pulmonary fibrosis, cystic fibrosis and COPD
- they produce spirographs
why is it not possible to expel all air from the lungs
the thorax cannot be completely flattened, as the trachea and bronchi are held open by cartilage
why are specialised exchange surfaces needed by some organisms
- helps to compensate for a low SA:V, as exchange surfaces have very high SA:V
- maximises efficiency of diffusion
- ensures the demand to O2 and glucose is met
4 features of an efficient exchange surface
- high SA:V
- thin layers/walls
- good blood supply to maintain conc gradient
- ventilation to maintain a conc gradient
breathing definition
the movement of air in and out of the lungs
gas exchange definition
the delivery of O2 from lungs into bloodstream and the elimination of CO2 from the blood stream
what occurs during forced expiration
- abdominal muscles contract, pushing diaphragm up
- this quickly makes lung pressure less negative
- internal intercostal muscles contract, pulling ribs down hard + fast
what is inspiration
movement of air into the lungs
this requires energy
what is expiration
the movement of air out of the lungs
this is a passive process
3 ways to measure lung capacity
- peak flow metre
- spirometer
- vitalographs
how does O2 get from the alveoli into the blood
dissolves into moist walls and diffuses from alveoli into capillaries down a concentration gradient
