Resp 2 Part 2 Flashcards
When in an upright position, there is a -- mmHg difference in pulmonary arterial pressure from the apex to the base of the lung. Due to ---!
23
gravity
Lung is divided into 3 zones: (3)
– Zone 1: most superior (apex of lung) – Zone 2: middle – Zone 3: inferior (base of lung)
Zone 3 (at Base) has the highest
hydrostatic
pressure and thus the
highest blood flow per
alveolus.
--- increases blood flow to all zones of the lung, though the bottom of the lung still receives the most blood flow.
Exercise
The hydrostatic pressure of the blood inside of the capillaries
(Pa) favors
filtration (and keeps the vessel open).
The tissue pressure (largely based on alveolar air pressure–
PALV) outside of the capillary
opposes filtration and favors
vessel collapse.
Only the (3) (alveolar vessels) are altered by PA.
capillaries &
smallest of the arterioles &
venules
Zone 1: (2)
Pa is lower than PA.
Capillaries are compressed.
Zone 1: (2)
Pa is lower than PA.
Capillaries are compressed.
If Pa drops (hemorrhage) or PA increases
(positive pressure breathing), a greater
potion of the lung is converted to
Zone 1
Zone 2: (2)
Higher Pa (due to gravity) means that Pa is higher than PA during
systole.
During diastole Pa will drop lower than PA. Thus blood flow is
intermittent.
Zone 3:
Highest Pa (due to gravity). Region of continuous blood flow because Pa remains higher than PA during both systole and blood flow
• Exercise converts
Zone 2 into Zone 3 blood flow.
• When in the supine position, the lungs have mostly Zone – blood flow because the – gradient is reduced .
2
gravity
Ventilation (V)/Perfusion (Q) Match
– Index of the match between air flow (alveolar
ventilation-V) & pulmonary blood flow (perfusion-Q)
Normal Whole Lung V/Q is 0.8 which means there is
more _________ flow than _________ flow.
blood
air
In a normal individual, the apex of the lung has a —
V/Q than the rest of the lung.
higher
As one moves from Zone 1 to Zone 3, there is a
— — in ventilation than blood flow.
slower increase
Fast, shallow breaths in upright position cause V/Q mismatch
because
air flows to upper lobes and blood to lower lobes.
Alveoli at the base of the
lungs receives more
— than those in
the apex.
ventilation
The pulmonary capillaries at
the base on the lungs receive
more — — than those in
the apex.
blood flow
Base of Lung: V/Q ratio
<1.0
Overall the base receives more blood flow
(perfusion) than ventilation.
Response to V/Q Mismatch (2)
These are negative feedback responses!
The respiratory & circulatory systems are working to deliver air and blood
to the same portions of the respiratory membrane.
If VENTILATION is limited, • V/Q is \_\_\_\_ • Thus O2 is \_\_\_ & CO2 is \_\_\_ • Smooth muscles in the \_\_\_\_ constrict
decrease
decrease
increase
vaso
f PERFUSION is limited,
• V/Q is ____
• Thus O2 is ___ & CO2 is ___
• Smooth muscles in the ____ constrict
increase
increase
decrease
BV
Blood traverses pulmonary capillaries in —
seconds and gas exchange must occur during this
time frame
0.3 -0.8
Fluid Filtration (F) is determined by (2)
Hydrostatic
Fluid Forces and Capillary and Interstitial Colloid
Fluid exchange also occurs as dictated by
Starling’s Forces
Hydrostatic Pressures (2)
- Capillary Pressure (Pc)
* Interstitial Fluid Pressure (Pif)
Osmotic Pressures (2)
• Plasma Colloid Osmotic
Pressure (p)
• Interstitial Fluid Colloid Osmotic
Pressure (if)
Filtration Pressures (Total = – mmHg)
29
Capillary Pressure (Pc) =
7 mmHg
Interstitial Fluid Pressure (Pif) =
-8 mmHg (use the absolute
value; the negative just tells you it is a filtration pressure)
Interstitial Colloid Osmotic Pressure (if) =
14 mm Hg
Plasma Colloid Osmotic Pressure (p) =
28 mmHg
filtration pressures (3)
• Capillary Pressure (Pc) = 7 mmHg
• Interstitial Fluid Pressure (Pif) = -8 mmHg (use the absolute
value; the negative just tells you it is a filtration pressure)
• Interstitial Colloid Osmotic Pressure (if) = 14 mm Hg
absorption pressures (1)
• Plasma Colloid Osmotic Pressure (p) = 28 mmHg
More negative than peripheral
interstitium—
GOOD since favors
fluid filtration from alveoli, too.
Normal filtration forces are greater
than the absorptive forces by —, so there is a
+1 mmHg (29-28)
slight
continual flow of fluid from the
pulmonary capillaries into the
interstitial spaces.
Fluid that leaves the capillaries is (2)
absorbed by
lymphatic circulation and returned to the
circulation
With a healthy respiratory and circulatory system,
— is maintained
balance
The balance of pulmonary capillary and interstitial
hydrostatic and colloid pressures can be disrupted
resulting in
pulmonary edema (large increases in net capillary filtration)
Pulmonary edema can occur with (3)
left sided heart failure,
mitral valve stenosis,
damage to pulmonary capillary membranes, etc.
