Test 3: Wk11: 2.1 Mechanisms of Ventilation - Dasgupta Flashcards
the — bronchus is slightly higher then then the —
right higher then left
the pleural space exerts a — pressure which makes the lungs
negative; stick to chest wall
When the diaphragm contracts and shortens it will flatted and
expand the volume of the thorax
parietal pleura is innervated by —
can they perceive pain?
intercostal nerves
yes, perceive pan
Visceral Pleura innervated by —
Can they perceive pain?
somatic nerves
no pain, only stretch
pleuritis
inflammation of pleural cavity
pleuritis causes
sharp severe chest pain which gets worse upon inspiration, coughing, sneezing, or laughing
Most common cause of pleurisy
viruses
Conduction Zone contians
Trachea
Bronchi
Bronchioles
Terminal Bronchioles
Transitional and Respiratory Zones contain
respiratory bronchioles
alveolar ducts
alveolar sacs
the airways bifurcate — times
~23
bifurcations 16-20
transitional zone of the lung
bifurcations 20-23
respiratory zone
extensive alveolar structures
anatomical dead space of the lung
no gas exchange - conducting zone
bifurcations 0-16
conducting zone
where does gas exchange occur
the last 4 bifurcations in the alveolar ducts and alveoli
Apnea:
Complete absence of spontaneous ventilation
Eupnea:
Normal spontaneous breathing.
Dyspnea:
Difficulty of breathing that the individual is aware of.
Bradypnea:
decrease of the respiratory rate
Tachypnea:
A rapid rate of breathing.
hyperventilation
Orthopnea
dyspnea which occurs when lying flat, causing the
person to have to sleep propped up in bed or sitting in a chair.
Compliance is
the measure of lung softness
Compliance =
delta V / delta P
Residual Volume
there is always a finite amount of air in the lung
Pressure in the lung is measure in
cm H2O
atmospheric pressure =
0 cm H2O
gas partial pressure are expressed in units of
mmHg
lungs are
passive
energy needed to pump gas into the lungs comes from
the chest wall
intrapleural pressure is always — during restive inhalation
negative
the recoil of the lung is
inward
the recoil of the chest wal is
outward
Functional Residual Capacity (FRC)
amount of air in the lungs when mouth is open and respiratory muscles are relaxed
Lung elastic recoil forces are a result of what 2 factors
- lung tissue elastic recoil
2. Surface tension forces
lung tissue elastic recoil is from
the polymer molecules that make up the lung. When mechanically inflated, they exert a recoil force
Surface Tension Forces are from
each alveolus is a water lined compartment where water exerts force that act to reduce the size of the surface - to collapse the lung
— is the main contributor to lung recoil
surface tension
— forces are responsible for surface tension
cohesive
within fluid forces are
balanced
at the surface of fluid forces are
unbalanced, the surface molecules are pulled inward
Laplace’s Law
P = T / r/2
T = tension
r = radius
Laplace’s law states that
P is inversely proportional to radius
collapsed alveoli are — but are —
not ventilated but are perfused
Shunt
vascular pathway in which there is no gas exchange
right to left shunt
blood comes from the right side of heart and goes through the lung without gas exchange
surfactant is made of
90% phospholipids and 10% proteins
Surfactant is secreted by
alveoli type II cells
the primary surface tension lowering surfactant is
DPPC
the hydrophobic end of surfactant allows
surfactant to spread across the fluid surface
the hydrophilic components of surfactant
insert themselves between water molecules along the surface lowering surface tension
the more concentrated surfactant the more surface tension is
lowered
absence of surfactant lung recoil is
very high
Alveoli A has radius of r
Alveoli B has radius of 2r
both have concentration of y surfactant
which has higher surface tension?
Alveoli B has higher surface tension because the same amount of surfactant is spread over a larger area
4x more surfactant in A than B
surface tension of B is 4x A
surface tension is — to surfactant
inversely proportional
Alveoli A has radius of r
Alveoli B has radius of 2r
which has greater pressure
Alveoli B, B will empty into A until they are equal
inhalation is an
active process
the diaphragm — during inhalation
contracts and moves down
the external intercostal muscles — during inhaltion
contract and lift ribs up
accessory muscles of shoulder girdle are
not involved in quiet breathing but can be used during exercise, coughing, and sneezing
accessory muscles in COPD and emphysema
used for inhalation
tripod position
physical stance used in pts with respiratory distress such as COPD
bent over with hands on knees
normal exhalation is a
passive process
during exhalation the diaphragm
relaxes
what drives gas out of the lungs
as the diaphragm relaxes, the vol of the thoracic cage and alveoli decrease, alveolar pressure becomes positve and gas leaves
what 2 things happen during forced exhalation
- internal intercostals contract
2. abdominal muscles contract to push guts and diaphragm up
Boyle’s Law
at constant temperature, pressure of a gas is inversely proportional to volume
Transmural Pressure (Ptm) =
Ptm = Palv - Ppl
Palv - alveolar pressure
Ppl - intrapleural pressure
