Exam 2: Pulm Physio Flashcards
(pulm volumes graph)
(pulm volumes graph)
Gas-exchange airways include:
Respiratory bronchioles
Alveolar ducts
Alveoli
Alveolar cells:
Type 1: gas exchange (super thin)
Type 2: surfactant production
Airway generation at which gas exchange begins:
~16
What is the respiratory exchange ratio?
The ratio of O2 in via food and CO2 out via metabolism
Protective benefits of faster exhalation than inhalation & mechanism by which this is accomplished:
Encourages elimination of dust & mucus/debris
Airways open during inhalation (slower gas velocity) and vice versa during exhalation
Why are spinal cord injury patients prone to pneumonia?
Can often breath, but not cough
ANS effects on airways:
Epinephrine opens airways
Function of alvolar pores:
Allow for collateral airflow if other alveoli ducts get clogged
Effects of interstitial thickening:
Harder for O2 to diffuse through
CO2 is slightly polar and can pass through more easily
Only thing between pleura:
Pleural fluid
Function of scalene muscles in breathing:
Lift the ribs
Function of trapezius in breathing:
None
Formula for alveolar surface tension:
P * R / wall thickness
Compliance is:
Ability to accept change in volume
Function of surfactant:
↓ surface tension of water
Relative pleural pressure during inspiration/end inspiration/expiration/end expiration:
Slightly negative at rest; more negative during inspiration; less negative (or even positive) during expiration
Under normal conditions, ventilation rate is driven by:
CO2
Under hypoxic conditions, ventilation is driven by:
Arterial CO2 tension (sensed by carotid body)
PO2, PCO2 in inspired air:
PO2: 159mmHg
PCO2: 0.3mmHg
PO2, PCO2, PH2O in alveolar air:
PO2: 104mmHg
PCO2: 40mmHg
PO2, PCO2 in pulmonary vein:
PO2: 100mmHg
PCO2: 40mmHg
PO2, PCO2 at tissues:
PO2: 40mmHg
PCO2: 46mmHg
PO2, PCO2 in pulmonary artery:
PO2: 40mmHg
PCO2: 46mmHg
Fetal hgb has ____ affinity to O2 than normal hgb:
Higher; needs to “steal” O2 from the maternal blood in the placenta
Factors that increase oxyhemoglobin affinity:
Alkalosis (↑pH) or ↓ PCO2 ↓ temperature ↓ 2,3 DPG Carboxyhemoglobin/methemoglobin Abnormal hgb
These are associated with decreased metabolism and thus decreased O2 need (so INCREASED affinity)
Factors that decrease oxyhemoglobin affinity:
Acidosis (↓ pH) or ↑ PCO2
↑ temperature
↑ 2,3 DPG - can be from high altitude
Abnormal hgb
These are associated with increased metabolism and stress, so decreased affinity/increased O2 delivery is a good thing
Left shift for Lounging around
Right shift for Running from a bear
Define P50 and how it is associated with the oxyhemoglobin dissociation curve:
The PaO2 at which hgb is 50% saturated; normally 26.6mmHg
Decreased affinity = high P50
Increased affinity = low P50
CO2 is ____x more soluble than O2:
30x
Most abundant protein in blood:
Hgb
90% of CO2 in the blood is found in this form:
Bound to hgb (the amino end, not the O2 binding site)
O2 content of blood equation:
1.34 * Hgb * SpO2 (+ 0.0003 * PO2)
Pulmonary response to hypoxia:
Vasoconstriction (unique to lungs) - shunts blood to better-ventilated regions
Hypoxia affecting the entire lungs can cause:
Pulmonary HTN
Pulmonary response to acidemia:
Pulmonary artery constriction
Describe high V/Q:
Impaired perfusion to alveolus means alveolar dead space and less oxygenated blood rejoining the system
Describe low V/Q or shunt:
Blocked ventilation (low V/Q) or collapsed alveolus (shunt) means no oxygenation of blood in that region
Describe lung zone I:
Hyperinflated alveoli, crushed capillaries
PA > Pa > PV
No blood flow
Describe lung zone II:
Pa > PA > PV
Blood flow occurs
Alveolar pressure compresses venules
Describe lung zone III:
Sad alveoli, engorged capillary
Pa > PV & PA
Blood flow fluctuates depending on PA and PV
Ideal FEV1/FVC:
> 90%
Spirometry measures:
Inspiratory reserve volume
Expiratory reserve volume
Vital capacity
Changes in the pulmonary system with aging:
Loss of elastic recoil Stiffening of chest wall (↓ compliance) Alterations in gas exchange ↑ in flow resistance ↓ vital capacity due to ↑ residual volume
Point in fetal development at which cuboidal epithelium in alveoli turns into type 1 cells:
28 weeks
Type II cells not working; these preemies need surfactant
