Section 5 Lecture 5 Flashcards
True or False? f and tidal volume impact effectiveness of ventilation.
T
Boyle’s Law:
P1V1 = P2V2
What is Dalton’s Law?
Partial pressure in a gas mixture is the pressure that the gas would exert if it occupied the total volume.
Henry’s Law:
concentration of a gas dissolved in a liquid is proportional to its partial pressure
What is the gas composition of air?
78% N2 and 21% O2
How to find the pressure of a gas:
Fraction of that gas X barometric pressure (check)
What is water pressure at sea level and saturation?
47
Gases in alveoli:
O2, N2, H2O, CO2, Argon
Ideal alveolar gas equation:
Pressure of oxygen in alveoli = (inspired pressure of oxygen - alveolar oxygen pressure) / Respiratory Quotient
Respiratory Quotient =
(R) (VCO2/VO2)
What does PACO2 have a huge impact on?
ventilation and brain blood flow
How are brain blood flow and CO2 levels affected by hyperventilation?
blood flow to brain decreases, hypocapnic
Will hypercapnia increase or decrease brain blood flow?
increase
What arterial pressure of CO2 will chemoreceptors sense?
above or below 40 mm Hg, tightly regulated value
High PACO2:
Resp acidosis
Respiratory alkylosis:
Low PACO2
This will lead to the exceeding of CO2 elimination need:
Hyperventilation
How does the PaCO2 vary between men and women?
it doesn’t. EVERYONE has the same PaCO2
Will dead space ventilation be bigger or smaller with more frequent ventilation?
bigger
As frequency of ventilation increases the alveolar ventilation
decreases
Are muscles more or less efficient with high frequency?
less
High frequency ventilation increases alveolar ventilation, and increases the work and energy cost of breathing
F. decreases alveolar ventilation, all else is T
Amount of alveolar dead space in the average person:
0
If the tidal volume is double the frequency of breathing is:
halved
If the breathing rate is increase 3 fold how is the tidal volume affected?
decreases 3 fold
How are tidal volume and breathing frequency related?
inversely (check)
Which patient will have a larger dead space ventilation, a patient with a tidal volume of 1000ml or a patient with a tidal volume of 200ml?
tidal volume of 200. This patient will have 5 times more dead space (dead space ventilation is inversely proportional to tidal volume) (check)
Increasing Vdot CO2 leads to:
an increases in alveolar ventilation and, therefore, V dot E
Increases oxygen consumption leads to:
proportional increase in ventilation as a result of changes in both TV and frequency
What od increases in V dot CO2 require?
an increase in V dot A
V dot A =
V dot E - dead space V dot
Volume of gas must match
perfusion
What has a profound effect on gas distribution in the lung?
Gravity pulls lung down to the diaphram, distended downward, changes in pr caused bystrectch , air volume at base is much less than the gas levels at the base
What is distribution of gas in the lung dependent upon?
Gravity
Maximum translung pressure in cm H2O:
30ish cm H2O
Average tidal volume at rest:
500ml, 3-5 ml/kg
Another name for physiological dead space:
functional dead space
Is there more blood flow at the bottom or top of the lung?
bottom
VA/Q of lung:
0.8
Arteries in contact with the alveolar for gas exchange get what % of blood flow?
98% the other % is shunted
limitation to diffusion of perfusion or a shunt:
difference of ? can be much bigger
PO2 less than __ is considered arterial hypoxemia:
less than 80
Hypoxia:
PO2 less than 60
Hypercapnia:
PCO2 above 40 (due to ventilation, perfusion abnormality)
Where is the anatomical shunt?
pulmonary a to v
How does the anatomical shunt affect the inspired O2
not affected
what can cause low ventilation
lung not fully inflated
physiological shunt:
venous mixture low vet with normal blood flow caused by atelectasis
Arterial hypoxemia:
blood comes thru without coming in contact with the alveoli
Is mismatch greater for O2 or CO2?
O2
True or False? increase in ventilation can quickly fix the mismatch in ventilation perfusion.
F
Relationship between CO2 disoscion is:
linear (check)
Effect of changing cardiac output?
decreases O2 and increases CO2 and vice versa
Abdnormal PaCO2
if is outside the normal limits for gas exchanges ?
When is there no inequality in ventilation perfursion
eliminate gravity, lie down, go in space, water
increase exercise leads to:
increase VaQ (check)
complete physiological shunt:
all blood goes through, zero ventilation, no oxygen pickup
blocked blood flow
ventilation = 1, blood flow = 0
Venous O2 =
40
Venous CO2 =
46
Normal right to left anatomical shunt:
carotid and bronchial circulation
Abnormal right to left anatomical shunt:
atrial-septal defect
True or False? The blood that goes through the shunt participates in gas exchange.
F
How is pulmonary capillary different than systemic?
lower pressure
How are lung volume and blood pressure affected with left heart failure?
increases pulmonary pressure, lung volume increase, lungs blood pressure increases, increases capillary pressure
Increase in venous pressure and increase in arterial pressure
lots of filtration, lung will fill with fluids, can’t exchange oxygen and patient dies. (changes in pulmonary edema)
loss of plasma proteins:
decreases oncotic pressure, starvation, increase permeability - fire-hot air, bacterial toxins - toxic shock syndrome
What would a pulmonary embolism lead to?
alveolar dead space
What can cause hypoxia?
decreased fraction of inspired oxygen (suffocation, high altitude), hyperventilation, decrease blood flow past alveoli, thickening of alveolar/capillary membrane, right to left shunt (without getting oxygenated)
Anatomic shunt:
atrial septal defect or ventricular septal defect
Physiological shunt:
ventilation to perfusion mismatch, (alveoli usually filled with pus or fluid)
Most common hypoxia:
V - Q mismatch (pulmonary edema or infection)
What makes up the physiological dead space?
Anatomical + Alveolar dead space
How much anatomical dead space does the average person have?
150ml
What % of the air in the normal person is wasted?
30%
What % of the total blood volumes is in the pulmonary circulation?
10% (50mL)
mL of blood in the alveolar-capillary network:
75mL
How much time is required for a passing red blood cell for full saturation?
1 sec
Surface area of the microcirculation:
70 m^2 (tennis court)
Bronchial circulation returns what % of cardiac output?
1%
Which can have less perfusion, lungs or muscles?
muscles
Why can perfusion to muscles be less than the lungs?
because of the lower resistance
How much less pulmonary vascular resistance is there than systemic?
10 times less
How much of a pressure drop is there with every 1 cm increase in height in pulmonary blood flow/
0.74 mHg or 5 cm
Is there more blood in apex or base of heart?
apex
True or False? If perfusion goes to apex, there will be no interface for exchange.
T
How will every 1 cm decrease in height effect pressure in the pulmonary system?
3.7 mm Hg muscles Waterfall effect
Describe hypoxic pulmonary vasoconstriction;
If there is a blockage of the lung (chocking) the alveoli will send a signal that there is not enough oxygen, leading to vasoconstriction of the arterioles. Blood will flow much more to the other side of the heart.
Is too much oxygen dangerous to the lungs?
yes
How is NO content altered with Increased airflow?
increases NO release
Why is NO released when there is higher blood flow
to lower resistane of arterioles
NO modifies the resistance to what?
higher flow rate of blood or gas, acts in both pulmonary and vascular systems
What neurotransmitter controls arterial vasoconstriction/
norepinephrine - alpha receptors
True or False? Ventilation and perfusion are distributed evenly throughout the lungs.
F
Pulmonary capillaries can can go from ___mL at rest up to _ mL.
75mL, 200mL
Functions of lung perfusion
reoxygenate blood and dispense CO2, fluid balance in lung, distribute metabolic products to and from the lungs
How do pulmonary arteries compare to systemic arteries?
less muscular and more compliant
What does the fact that the pulmonary arteries are less muscular and more compliant allow for?
lower resistance and pressure
Factors that affect blood flow (perfuson) through the lungs:
pulmonary vascular resistance, gravity, alveolar pressure, arterial to venous pressure gradient
Mean pressure of __ in the pulmonary arteries
14 mm Hg
True or False? systemic flow = pulmonary flow
T
Is there a lower pressure gradient in the pulmonary system or the arterial?
pulmonary
Is a left to right shunt favored or a right to left shunt?
left to right
Highest to lowest pressure above the heart: arterial, alveolar, venous?
alveolar, then arterial, then venous
Highest to lowest pressure at level of heart: arterial, alveolar, venous?
arterial, alveolar, venous
Highest to lowest pressure below heart: arterial, alveolar, venous?
arterial, venous, alveolar
Which portion of the lungs has the highest transmural pressure, the top, the middle, or the bottom?
bottom, distends vessels, high perfusion
Does the top or bottom of the lung have a higher volume?
bottom
Does the top or bottom of the lung have a higher V dot A?
bottom
Does the top or bottom of the lung have a higher Q dot?
bottom
Does the top or bottom of the lung have a higher V dot A/ Q dot?
top (apex)
Does the top or bottom of the lung have a higher PO2?
bottom
Does the top or bottom of the lung have a higher PCO2?
bottom
Does the top or bottom of the lung have a higher p H?
top
Does the top or bottom of the lung have a higher O2?
bottom
Does the top or bottom of the lung have a higher CO2?
bottom
How many times greater is the V dot A in the bottom of the lungs than the top?
3.4 times
How many times greater is the V dot A/ Q in the bottom of the lungs than the top?
18 times
Vol in apex is (greater than/less than) mid region.
less than
What decreases at a greater rate when going from the bottom of the lungs to the top, ventilation or perfusion?
perfusion
Shape of V dot A/ Q dot graph:
right half of a shallow “U”
poor VA/Q means what?
arterial hypoxemia
Total flow is __ and alveolar flow is __.
5, 4
Normal VA/Q:
0.8
When does the alveolar-arterial PO2 difference increase?
with age and in lung disease
What % of cardiac output is shunt?
2-3%
Which is higher, alveolar or arterial PO2?
alveolar
PO2 less than 80:
arterial hypoxemia
PO2 less than 60:
Hypoxia
PCO2 above 40:
Hypercapnia
PCO2 less than 35:
hypocpnia
How is inspired O2 affected with an anatomical shunt?
it’s not
Is ventilation normal, high, or low with a physiological shunt?
low
is blood flow normal, high, or low with a physiological shunt?
normal
