respiratory 1 Flashcards
conducting some of the respiratory system
respiratory passages that carry air to the site of gas exchange
filters, humidifies and warms air
respiratory zone of the respiratory organs
site of gas exchange composed of - respiratory bronchioles - alveolar ducts - alveolar sacs
respiratory membrane
air-blood barrier
- oxygen diffuses from air an alveolus to blood in capillary
- carbon dioxide diffuses from the blood in capillary to air in the alveolus
capillaries around alveoli
spread around the surface of the alveoli to match the surface area
alveoli interconnect by
alveolar pores
functions of the Plura
- reduction of friction
- create suction
- compartmentalisation two prevents infection
Boyle’s law
gas pressure is closed container is inversely proportional to volume of the container
gas will fro from regions of high pressure to regions of low pressure
to get air to the alveoli
their pressure must be reduced below atmospheric pressure
how is air pressure is the alveoli reduced below atmospheric
increase chest volume
tidal breathing
only the diaphragm muscle is used, intercostal is active in inspiration
expiration is a passive process relying on elastic recoil of lungs, chest wall, abdominal contents
in forced breathing
inspiration recruits other muscles
- the pectoral muscles, scalene and sternocleidomastoid muscles
- inverse reserve volume
forced costal expiration
- internal intercostals, transverse thoracic muscles, rectus abdominus, external oblique, internal oblique transversus abdominus
- pelvic flood muscles must be active too
intra-pleural pressure
pressure between visceral and parietal pleura
sucks lungs to the chest wall
must always be negative
if intra-pleural pressure is positive
pneumothorax will occur due to the lung collapsing because suction is lost
intra-pleural pressure quantity
-5 cm H2O
intra-pleural pressure changes depending on
whether you’re breathing in or out
trans-airway pressure
the difference between the trachea and the plueral pressure
difference must be positive
if the trans-airway pressure is negative
airways may collapse during forced expiration
transpulmonary pressure
pressure between alveolar and pleural pressure
must be positive otherwise the lung will collapse
alveolar pressure changes depending on
whether you’re breathing in or out
atmospheric pressure is
760 mm Hg
intra pleural pressure is
756 mm Hg
alveolar pressure is
varies with insp/exp
inspiration
diaphragm and intercostal contract
increases volume of the thoracic cavity
lung volume increases
alveolar pressure decreases
alveolar pressure during insp
758 mm Hg
expiration
muscles relax - or active if forced expiration
volume of the thoracic cavity decreases
lung volume decreases
alveolar pressure increases
alveolar pressure during expiration
763 mm Hg
total lung capacity
6L
inspiratory reserve volume
difference between maximum tidal and total lung capacity
maximum voluntary expiration
point at total - residual volume
residual volume
amount that always remains in the lungs
inspiratory capacity
tidal + inspiratory reservee
vital capacity
total - residual volume
expiratory reserve volume
different between lowest tidal and residual volume
functional residual capacity
total - inspiratory capacity
normal total volume
500ml
normal inspiratory reserve
3100ml M / 1900ml F
normal expiratory reserve
1200ml M / 700ml F
normal residual volume
1200ml M / 1100ml F
normal functional residual capacity
2400ml M / 1800ml F
normal vital capacity
4800ml M/ 3100ml F
normal total lung capacity
6L M / 4.2L F
normal inspiratory capacity
3600ml M / 2400ml F
what can’t be measured by spirometry
residual volume
how to measure residual capacity
spike with helium and measure concentration over time
lung volumes and work
inflation of lungs above functional residual capacity required the respiratory muscle to generate sufficient pressure to expand the lung - overcome elastic recoil
deflection below FRC required expiratory muscles to compress the chest to overcome chest stiffness
dead space
some inspired air never contributes to gas exchange
alveolar dead space
alveoli that cause to act in gas exchange due to collapse or obstruction
total dead space
sum of alveolar and anatomical dead space - all non useful volume
anatomical dead space
volume of conductive zone conduits approx. 150ml
minute ventilation
TV x f
total volume x frequency (breaths/min)
volume of air expired per minute
alveolar ventilation
(TV-DV) x f
total volume - dead volume x frequency
alveolar ventilation effieicny
increase frequency or increase volume
invreasing volume by taking deeper breaths is more efficient that increasing frequency
rapid shallow breathing
does not increase alveolar ventilation due to the effects of dead space
