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Physiology Flashcards

1
Q

tidal volume (VT)

A

volume of normal breathing

0.5 L

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2
Q

inspiratory reserve volume (IRV)

A

additional amount of air that can enter during forced inspiration

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3
Q

expiratory reserve volume (ERV)

A

difference between tidal end volume and forceful expiration end volume

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4
Q

residual volume (RV)

A

amount of air remaining in the lung at max expiration

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5
Q

inspiratory capacity (IC)

A

VT + IRV

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6
Q

functional residual capacity (FRC)

A

ERV + RV

volume of air in the lungs after normal expiration

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7
Q

vital capacity (VC)

A

IC +ERV

volume that can be expired after max inspiration

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8
Q

total lung capacity (TLC)

A

VC + RV
includes all lung volumes
6-7 L
most sensitive test for restrictive lung disease

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9
Q

forced vital capacity (FVC)

A

TV + IRV + ERV

amount of air exhaled during a forceful expiration

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10
Q

forced expiratory volume in 1 second (FEV1)

A

max inspiration then forced expiration

normal is 80% of FVC

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11
Q

obstructive lung disease

A

FEV1: FVC ratio reduced: less than 70%
increased: TLC, RV, FRC
reduced: FVC, FEV1
difficult expiration: increased compliance, decreased Patm and Palv pressure: collapses airways on forced exhalation
ex: asthma, emphysema, chronic bronchitis, bronchiectasis

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12
Q

restrictive lung disease

A

reduced FVC, FEV1, TLC, RV, FRC
normal or increased FEV1: FVC ratio
difficult inspiration: decreased compliance, increased resistance
ex: obesity, weak inspiratory mescles, neuromuscular disorder, interstitial lung disease (fibrosis), ARDS, sarcoidosis, pneumonitis

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13
Q

atelectasis

A

unstable alveoli that collapse on expiration

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14
Q

Normal arterial PO2 and PCO2.
Normal venous PO2 and PCO2.
Normal alveolar PO2 and PCO2.

A 
systemic arterial/ pulmonary venous:
PO2: 100
PCO2: 40
systemic venous/ pulmonary arteries: 
PO2: 40
PCO2: 46
alveolar:
PO2: 105
PCO2: 40
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15
Q

hypoventilation

A

increase in PACO2

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16
Q

hyperventilation

A

decrease PACO2

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17
Q

V/Q ratio for base and apex of lung

A

apex: high V/Q ratio (wasted ventilation)
base: low V/Q ratio (wasted perfusion)

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18
Q

What part of the lung is most perfused and has the most alveolar ventilation? least?

A

most perfused and alveolar ventilation: base

least perfused and alveolar ventilation: apex

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19
Q

A-a gradient for different causes of hypoxemia:

  1. hypoventilation
  2. decreased PIO2
  3. diffusion limitation
  4. R to L shunts
  5. V/Q mismatch

Which cannot be corrected by 100% O2?

A
  1. normal
  2. normal
  3. increased
  4. increased, NOT corrected with 100% O2
  5. increased
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20
Q

Decreased PIO2

  1. Example?
  2. A-a gradient increase? Intrinsic lung disease?
  3. Corrected with 100% O2?
A
  1. increased altitude
  2. A-a does NOT increase; no
  3. corrected with 100% O2
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21
Q

Hypoventilation

  1. Example?
  2. A-a gradient increase? Intrinsic lung disease?
  3. Corrected with 100% O2?
A
  1. drug overdose
  2. A-a does NOT increase; no
  3. corrected with 100% O2
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22
Q

Diffusion limitation

  1. Example?
  2. A-a gradient increase? Intrinsic lung disease?
  3. Corrected with 100% O2?
A
  1. pulmonary fibrosis, hard exercise, emphysema
  2. increased; yes
  3. yes
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23
Q

R to L Shunt

  1. Example?
  2. A-a gradient increase? Intrinsic lung disease?
  3. Corrected with 100% O2?
A
  1. ASD/VSD after pulmonary HTN reverses original L to R shunt; ARDS (alveolar flooding and collapse causes shunt)
  2. increased; yes
  3. NO
    IMPORTANT: 100% oxygen should have a very large increase in PaO2: do the equation for A-a gradient to see if it is corrected
    ex: PAO2= (760-47) x 1 - PaCO2/1
    FiO2=1 at 100% O2
    R= 1 at 100% O2
    PaO2 should be in 600s; if not: shunt
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24
Q

V/Q mismatch

  1. example
  2. A-a gradient increase? Intrinsic lung disease?
  3. Corrected with 100% O2?
A 
MOST COMMON cause of hypoxemia
1. emphysema, obstructive
2. increased; yes
3. yes
normal whole lung V/Q: 0.8
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25
Low V/Q diseases
V/Q less than 1: low ventilation 1. obstructive disease (asthma, COPD) 2. pulmonary edema 3. SHUNT (most extreme of low V/Q)
26
High V/Q diseases
V/Q more than 1: low perfusion 1. pulmonary embolism 2. DEAD SPACE like no blood flow (most extreme high V/Q)
27
DLCO
High: early asthma, pulmonary alveolar hemorrhage, exercise, early CHF, obesity Low: COPD, fibrosis, emphysema, interstitial lung disease, PAH/PE, anemia
28
pulmonary shunt
V/Q= 0 | unventilated alveoli with preserved perfusion or A-V malformations
29
How can you use DLCO to differentiate between obstructive diseases (asthma and COPD)?
high: asthma low: emphysema
30
How can you use DLCO to differentiate between restrictive diseases (chest wall vs. interstitial lung disease)?
high: chest wall low: interstitial lung disease
31
isolated low DLCO indicates what type of disease
pulmonary vascular disease | pulmonary HTN/ pulmonary embolism
32
ventilation
exchange of gas between atmosphere and alveoli
33
diffusion
exchange of O2 and CO2 between alveolar air and lung capillaries DOWN pressure gradient
34
inspiratory muscles
diaphragm (phrenic nerve) | accessory: scalene, sternocleidomastoid, external intercostal muscles
35
expiratory muscles
passive at rest | exercise/force: rectus abdominus, internal and external oblique, transverse abdominus, internal intercostal muscles
36
interdependence
if one alveolus has a tendency to collapse, it will be counteracted by expanding forces of surrounding alveoli
37
how does surfactant work
phospholipid (dipalmitoyl phosphatidylcholine, lecithin, sphingomyelin) that breaks polar attraction of water molecules and reduces surface tension: prevents atelectasis deep breath stretches type II cells and stimulates surfactant production
38
surface tension
attractive forces between liquid molecules pulls surface molecules together at air-liquid interface
39
Which has more airway resistance: mouth or nose?
nose
40
How does lateral traction affect airway resistance?
elastic connective tissue fibers attach to airway exterior and pull outward: holding airways open
41
How does lung volume affect airway resistance?
increase in lung volume increases airway diameter and resistance decreases
42
How does relaxation/contraction of bronchial smooth muscle affect airway resistance?
relaxation: decreases resistance contraction: increases reaction
43
What is the driving stimulus for respiration?
PaCO2 | hyperventilation attenuates stimulation of respiration because PaCO2 is decreased
44
hypoxemia
lower than normal arterial PO2 | normal = 100 mmHg
45
hypoxia
decreased O2 delivery to tissues | due to: decreased blood flow or decreased O2 content
46
hypercapnia
high arterial PCO2 normal= 40 mmHg most often due to hypoventilation
47
where is most of gas exchange completed (even in exercise)?
initial region of pulmonary capillary | PERFUSION limited: all blood leaving capillary has reached equilibrium with alveolar gas
48
diffusion limited gas exchange diseases
gas does not equilibrate between capillaries and alveolar gas 1. CO poisoning 2. fibrosis (thick barrier) 3. emphysema (decrease SA) 4. high altitude 5. INTENSE exercise
49
What determines pulmonary blood flow?
PAO2
50
How is edema fluid cleared?
repair epithelium Na from interstitium comes into cell (ENaC) and is then pumped to basolateral side (Na-K ATPase) and water follows (aquaporin)
51
partial pressure (PO2)
dissolved O2 in plasma
52
methhemoglobin
Fe3+: O2 can't bind | caused by nitrites and sulfonamides
53
HbF
alpha2gamma2 | high affinity O2
54
adult Hb
alpha2beta2 | Fe2+
55
HbS
sickle cell
56
cyanosis
unsaturated hemoglobin is purple | low Hb saturation causes blue color
57
CO poisoning
1. decreases O2 carrying capacity because it binds more strongly to Hb (decreases O2 content) 2. also increases affinity of O2 for Hb and makes unloading in tissues more difficult
58
Hamburger's phenomenon
diffusion of HCO3- into plasma causes a decrease in net neg. charge in cell Cl- moves into cell to compensate dragging water into cell causing it to swell
59
band three protein
drives Cl- shift into cells HCO3- leaves cell
60
How are H+ ions buffered in RBC after HCO3- leaves?
buffered by deoxyhemoglobin to prevent acidification
61
Bohr effect
when CO2 is produced by tissues, HCO3 and H+ are produced in blood. due to H+ production, pH becomes lower. higher H+ concentration increases H+ binding to Hb and decrease in O2 affinity: O2 unloads in tissues (right shift)
62
Haldane effect
oxygenation of Hb displaces CO2 from carboxyhemoglobin to form oxyhemoglobin shifts equilibrium toward CO2 formation: CO2 is released from RBC's into plasma increases PCO2
63
respiratory acidosis
``` low pH PCO2 greater than 40 cause: hypoventilation ex: obstruction, acute or chronic lung disease, sedatives/opioids, weak respiratory muscles compensation: increase HCO3 (slow) ```
64
respiratory alkalosis
``` high pH PCO2 less than 40 cause: hyperventilation ex: hysteria, hypoxemia, high altitude, salicylate, tumor, PE compensation: decrease HCO3 (slow) ```
65
metabolic acidosis
low pH PCO2 less than 40 low HCO3 compensate: hyperventilation (immediate)
66
metabolic alkalosis
high pH PCO2 greater than 40 high HCO3 compensate: hypoventilation (immediate)
67
central chemoreceptors
MOST IMPORTANT respond to change in brain extracellular fluid MEDULLA stimulus: decrease in pH (increased PCO2) MINUTE to MINUTE breathing
68
peripheral chemoreceptors
``` respond to changes in arterial blood 1. PO2 less than 60 mmHg: increase ventilation 2. changes in pH increase (exercise): hyperventilation decrease (vomit): hypoventilation 1. carotid bodies 2. aortic bodies anemia does not stimulate ```
69
carotid bodies
stimulus: decreased PO2 greater than PCO2 greater than decreased pH RAPID: PO2 less than 60 mmHg high blood flow is key: EXERCISE
70
aortic bodies
RAPID | stimulus: decreased P02 greater than PCO2
71
lung receptors
1. pulmonary stretch receptors 2. irritant receptors 3. J receptors
72
pulmonary stretch receptors
stimulated by lung distention | Bering-Breuer reflex: slows down frequency
73
irritant receptors
stimulated by noxious gas, smoke, dust, cold air, low PCO2 causes hyperpnea and bronchoconstriction hypersensitive: asthma
74
juxtapulmonary capillary receptors (J receptors)
stimulated by increase in pulmonary interstitial fluid | causes shallow, rapid breathing, apnea, hypotension
75
nose and upper airway receptors
role in sneezing, coughing, bronchoconstriction
76
joint and limb muscle receptors
role in early adjustment to exercise
77
muscle spindles within respiratory muscles
sense muscle elongation
78
arterial baroreceptors
increase BP can cause reflexive hypoventilation
79
pain and temperature receptors
trigger period of apnea followed by hyperventilation
80
What happens when a patient has a chronic elevation of PCO2?
adaptation of central chemoreceptors: brain extracellular pH reset by increased HCO3 transport (normal brain fluid pH at high arterial PCO2) ex: COPD oxygen becomes chief stimulus of ventilation through peripheral chemoreceptors IMPORTANT: raising PO2 by placing patient on O2 may remove any stimulus to breathe and cause sudden death (MONITOR)
81
response to exercise
1. arterial PO2 constant: ventilation and O2 consumption increase in proportion 2. moderate: alveolar ventilation increases in proportion to CO2 production; venous PCO2 increases but arterial PCO2 remains constant 3. strenuous: lactic acid is released increasing arterial pH; arterial PCO2 decreases due to hyperventilation
82
response to high altitude
decreased inspired PO2 1. immediate: hyperventilation: respiratory alkalosis 2. several days: renal HCO3 excretion increases, HCO3 leaves CSF, pH of CSF decreases to normal; hyperventilation resumes 3. hypoxia stimulates EPO synthesis 4. increased 2,3- DPG causes right shift (decreased affinity) 5. increase pulmonary resistance: hypertrophy of right ventricle
83
causes for worsening hypercapnia with supplemental O2
1. Haldane effect | 2. increased O2 abolishes hypoxic induced vasoconstriction: increased blood flow to low ventilation (low V/Q) areas
84
spirometry
expiration for at least 6 sec measures vital predictors: age, sex, Ht
85
What can a plethysmograph measure that a spirometer cannot?
residual volume
86
What part of the flow volume loop is effort independent?
end of expiration
87
Scoop on flow volume loop
COPD
88
hamburger on flow volume loop
upper airway obstruction (inspiratory stridor): vocal cord paralysis, tracheal stenosis, goiter
89
How is DLCO measured?
``` single breath need inhaled VC greater than 1 L hold breath for 10s CO due to high affinity for Hb normal 81-140% ```
90
What decreases FRC?
obesity, pregnancy, ascites | restrictive disease
91
Is peak flow effort dependent or effort independent?
dependent

Pulm (11 decks)

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