Pulm 1 Flashcards
(425 cards)
1
Q
What is the function of the respiratory system?
A
Gas exchange (warm/humidify the air and filter and protect us from it)
Acid-base
Phonation
Metabolism of endogenous substances
2
Q
How much blood passes through lungs each minute?
A
Entire blood volume (~5L)
3
Q
How is the lung anatomically divided?
A
4
Q
What are the functions of the airways (conducting zone)?
A
Serve as conduits of air
Provide for evacuation of foreign material
Provide immunologic and protective functions
Serve to warm and humidify the air as it enters
5
Q
What are features of Respiratory Epithelium?
A
6
Q
How do bronchi and bronchioles differ histologically?
A
7
Q
What is the funcitonal subunit of hte lung?
A
Acinus
8
Q
What are features that allow for efficient and rapid gas exchagne?
A
Large surface area
Short diffusion path
Concentration gradient
9
Q
What does the lung look like at the alveolus?
A
10
Q
What are Type 1 vs Type 2 pneumocytes?
A
Type 1 = cover ~95% of alveolus, but are only 40% of cells - cant’ divide
Type 2 - cover ~5% but account for 60% of cells. Divide to replace type I cells
11
Q
What factors can influence anomalous funciton of thel ugns?
A
Gas exchange impairment in alveolar space
Increase in air flow resistance in bronchioles
Altered pulmonary mechnaics
12
Q
What is ventilation-perfusion mismatch?
A
Area receiving blood isn’t the same as area receiving fresh air
E.g. neoplasm, mucous plugging, COPD, edema, pneumonia
13
Q
What do we see here?
A
Mucus plugging in chornic bronchitis limits airflow to alveolar gas exchagne areas
14
Q
What are alveoolar filling processes?
A
Pneumonia, edema
Fluid and inflammation occupies alveolar space preventing acess to the area of gas exchange
15
Q
What do we see here?
A
Acute pneumonai - neutrophils fll alveolar spaces
16
Q
How can you impair diffusing capacity?
A
Loss of alveolar or endothelial area (emphysema)
Thickening of alveolar wall (fibrosis)
17
Q
What are two factors upon which diffusing capacity depends?
A
Alveolar and endothelial surface areas
Thickness of air-blood barrier
18
Q
What do we see here?
A
Real bad emphysema - decreased alveolar surface
19
Q
What do we see here?
A
Interstitial fibrosis - increased thickness of alveolar walls inhibits gas exchage
20
Q
What are some obstacles to perfusion?
A
Destruciton of alveolar capillaries
Alteration of pulmonary blood flow (cardiac, pulmonary HTN)
Obstruciton of blood flow (PE, compression)
21
Q
What are general features of the pulmonary vasculature?
A
Dual circulation:
Pulmonary arteries (low pressure, capacitance, gas exchagne)
Bronchial arteries (systemic pressure, nutrient vessels)
22
Q
What do we see here?
A
Pulmonary HTN - increased htickenss of pulmonary vessels - decreased blood flow to gas exchange areas
23
Q
What are structural mechanisms for defense in the lungs?
A
Nasal hairs
branching airways
Muco-ciliary escalator
Alveolar macrophages
24
Q
A 55 year old man presented to the ED with shortness of breath. His exam shoes dullness to percussion, absence of breath sounds at the left base. The AP chest radiograph shows
opacification onf the left hemithorax. Fluid in the chest is suspected The next step is to order:
A. Lateral decubitus film
B. Apical lordotic film
C. CT scan of the chest
D. PA and lateral film
E. Supine chest xray
A
Lateral decubitus film
25
What is the PA view?
Patient is upright and in full inspiration
XR tube is 6 feet from film
26
What is the lateral CXR?
Left side of patient against XR cassette
Helpful in visualizing lesions behind the heart the mediastinum or diaphragm
27
What is the AP view?
Portable XR unit on sick patients - supine or sitting in bed
XR passes from anterior to posterior
Less powerful, higher magnification, less sharp images (taken from shorter distance)
28
Which is PA, which is AP?
29
What is a lateral decubitus view?
Patient lies on his side in lateral position
Helps visualize free fluid in pleural cavity as it will gravitate and layers against dependent thoracic wall
30
What are expiratory views?
Help visualize free air in pleural cavity (pneumothorax) as the lung markings becoem more crowded which help delineate edge of lung
31
What is the apical lordotic view?
Frontal view taken with XR beam angled to project clavicles above the lung apex to display disease hidden behind the clavicles
Seen on right
32
Identify the structures on this xray
33
Identify the structures
34
What are demarcations of the right and left lung?
Right has RUL, RML, RLL
Left has LUL and LLL
Major fissure separates RUL and RML from RLL on right and the LUL from LLL on left
Minor fissure separates RUL from RML
35
what is lung compliance?
Volume/Pressure
36
What is the compliance of the chest wall?
37
What is the compliance of the respiratory system?
Combination of the chest wall and lungs
38
What is hysteresis?
The chest wall compliance is different in inflation than in deflation
39
Why is there hysteresis?
Surface tension increases the pressure needed to expand the lung
Surfactant helps
40
What are surface forces of the lung?
Air liquid interface adds to pressure to required to expand lungs
Saline filled lungs requrie less pressure
Surfactant reduces surface tension (decreases further when lungs get smaller) and prevents small airway and alveoli collapse
Surfactant is made by Type II pneumocytes
41
What cells make surfactatn?
Type II pneumocytes
42
What are tissue forces of elastic recoil/
Beyond a certain point of inflation, lungs get stiff
Below a minimum, alveoli stay open because of their structur
43
How does compliance change with disease?
ΔV/ΔP
44
What decreases lung compliance?
Pulmonary fibrosis
Pulmonary Edema
Pneumonia
45
What increases pulmonary compliance?
Epmhysema
Normal Aging
46
What do you see here?
Left: normal
Right: empnysematous lung - decreased elastic recoil, increased airflow resistance
47
What are pressures during tidal breath?
Pleural- always negative
Alveolar - correlates with flow
48
What is Reynolds number?
Density \* diameter \* velocity / Gas viscocity
Higher number =\> turbulent flow more likely
49
What characterizes air flow in large airways?
Turbulent flow
Resistance increases as flow increases
Helium/oxygen mixture decreases density and increases viscocity and is used to improve flow during turbulent flow conditions (upper airway obstuction)
50
How can you improve flow under turbulent flow conditions (e.g. upper airway obstruction)?
Provide a helium:oxygen mixture that decreases density and slightly increases viscocity improving the Reynolds number
51
What descries airflow in smaller airways?
Laminar flow and Poisseuille's Law
Resistance is proportional to viscocity\*length/radius^4
Airway radius is most impmortant factor in resistance
52
Where is there the most resistnace to airflow?
Larger airways - there are SO many smaller airways, that the laminar flow dynamics of the small radii doesn't come into play
53
What does FEV1/FVC ratio decrease indicate?
Obstructive defect
54
What defines restriction?
Reduced lung volumes (not just spirometry)
55
What does reduced "diffusion capacity" indicate?
Gas transport defect, but not much else
56
What are spirometry measurements?
57
What are the lung volumes?
58
What should your FEV1 typically be?
~ 3/4 of full expiratory volume (vital capacity)
59
How do you measure FRC, and by extension reserve volume?
Helium dilution after equilibration
Body phlethysmography
60
Does diffusion limit oxygen transport?
No - a RBC spends more than enough time in the capillary to diffuse (1 second or so)
61
In a patient with emphysema, lung compliance would be expected to be
A) Decreased
B) Increased
C) Generally unchanged
D) Cannot predict
Increased - not necessarily a good thing
62
Most of the resistance to airflow in the lung comes from
A) Large airways B) Small airways C) Alveoli
Large (not intuitive)
63
Functional Residual Capacity is the volume of the lungs
A) When you take the biggest possible breath B) When you let all your air out
C) When you are dead
When you're dead
64
What is physiologic dead space?
Total volume of lungs that doesn't participate in gas excahnge
Anatomic dead space (conducting airways) + functional dead space (ventilated alveoli that do not participate in gas exchange)
65
What is the anatomic dead space?
Volume of conduncting airways (~150 mL)
Nose, mouth, trachea, bronchi, terminal bronchioles
66
What is functional dead space?
Abnormal to have
Ventilated alveoli that don't participate in gas exchange
Due to mismatch of ventilation and perfusion (v and q)
67
How do we measure dead space?
compare partial pressure of CO2 in alveoli and partial pressure of CO2 in expired air
VD = VT X [(PaCO2 – PECO2)]/ PaCO2
You typically use Vd/Vt ratio: Vd/Vt = (PaCO2 - PeCO2) / PaCO2
68
What is minute ventilation?
Tidal volume \* respiratory Rate
Ve = Vt \* RR
69
what is normal tidal volume?
450-500mL
70
What is normal minute ventilation?
~6.3 liters/minute
71
What is alveolar ventilation?
Minute ventilation - dead space ventilation
Va = RR\*(Vt - Vd)
72
What is the alveolar ventilation equation?
INverse relationship between alveolar ventilation and alveolar PACO2 when the rate of CO2 produciton is constant
PACO2 = VCO2 \* K / VA
K = constant for body temp, ampbient pressure standard (863)
73
What does the alveolar ventilation equation tell us?
If VCO2 doubles (strenuous exercise) then the only way to maintain the normal value of PACO2 is for VA to double also
When VA is doubled then PACO2 is halved
74
What is the alveolar gas equation/
Describes relationship between alveolar CO2 and O2
PAO2 = PIO2 - PACO2/R
R is respiratory exchange ratio (CO2 produciton/O2 consumption); normal is 0.8
75
What ist he normal respiratory exchange ratio?
0.8
76
A man has a rate of CO2 production that is 80% of rate of O2 consumption. If his arterial PCO2 = 40 mmHg and PO2 in humidified tracheal air is 150 mmHg, what is his alveolar
PO2?
Assume arterial blood equilibrates with alveolar. So PaCO2 = PACO2
PAO2 = PIO2 - PACO2/R
150-40/.8 = 100mmHg
77
How is perfusion different in the lung?
Zone 1= apex
Zone 2 = middle
Zone 3 = base - best perfusion
78
How is ventilation different in different regions in the lung?
Also varies with gravity
Gravity produces differences in regional ventilation
V is highest in base of the lung
79
How is V/Q different throughout the lung?
Actually ends up being highest at the top of the lung!
80
Which area of the lung has best V/Q ratio, which has lowest?
Highest in zone 1 (top)
Lowest in zone 3 (base)
81
What is happening when V/Q = 0?
Shunt = perfusion without ventilation
82
What happens when V/Q =\> infinity?
Ventilation without perfusion
dead space
83
What is Dead space (V/Q = infinity)?
Since there is lack of blood flow, O2 can't be received or CO2 cant be added to alveolar gas
E.g. Pulmonary Embolism
84
What occurs in a shunt?
Lack of ventilation
NO O2 from alveolar gas to deliver to blood ro CO2 from blood to be eliminated
E.g. airway obstruction or right to left cardiac shunt (ASD)
85
What is the fractional concentration of oxygen in the air?
21 % so partial pressure is 760 \*.21= 160 mmHg
86
How does the partial pressure of oxygen change from atmosphere to lungs?
Humidified air includes vapor pressure of weather
Atmosphere is 21% oxygen so 760\*.21, but humidified is 760 - vapor pressure of water
so its less
87
What is venous partial pressure of oxygen?
40
88
What is venous partial pressure of carbon dioxide?
46
89
What is arterial partial pressure of oxygen?
100
90
What is arterial partial pressure of carbon dioxide?
40
91
What is perfusion limited gas exchange/
Total amount of gas transported across alveolar/capillary barrier is limited by blood flow (perfusion)
Partial pressure gradient isn't maintained, so only way to increase amoutn of gas transported is by icnreasing blood flow
92
How do O2, CO2, and N2O Gas exchange?
Perfusion limited
93
What is diffusion limited gas exchange?
Total amount of gas transported across the alveolar-capillary barrier is limited by diffusion process
As long as partial gradinet is maintained, diffusion will continue along the lenght of capillary
e.g. CO
94
How does CO gas exchange?
Diffusion limited
95
What are examples of diffusion limited gas exchange?
CO
O2 in emphysema, pulmonary fibrosis or exercise
96
How much oxygen/gm does hemoglobin carry?
1.34
97
What is the O2 content of blood?
O2 bound to HbA + Dissolved O2
Bound to HbA is Hb conc \* 1.34 \* % saturation
98
WhatisO2 contentofthe blood of a patient with anemia (Hb 10 gm/dL)?
Assuming normal lungs hence normal PAO2 of 100 mmHg and normal PaO2 of 100 mmHg
Hb is 98% saturated at PaO2 of 100 mmHg
O2 boundtoHb=10gm/dLx 1.34 mL O2 / gm Hb X 98% (saturation) = 13.1 mL O2/100 mL blood
Total O2 content = above value + dissolved O2
Dissolved O2 = PaO2 X solu = 100 mmHg X 0.003 mL O2/100 mL/mmHg = 0.3 mL O2/100 mL blood
Total O2 content = sum of above = 13.1 + 0.3 = 13.4 mL O2/100 mL blood
99
What is the O2-Hb Dissociation curve?
Reversible binding of up to 4 molecules of O2
P50 = PO2 at which Hb is 50% saturated = 24 mmHg
100
What makes the O2-Hb dissociation curve shift to the right?
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