Physiology Flashcards
Air that can be breathed in after notmal inspiration
Inspiratory reserve volume
Air that moves into lung with each quiet breath
Tidal volume (~500mL)
Ait that can be breathed out after normal expiration
Expiratory Reserve Volume
Air in lung after max expiration; cannot be measured by spirometry
Residual volume
TV + IRV
Inspiratory Capacity
Volume in lungs after normal expiration
Functional residual capacity
Maximal volume of gas that can be expired after a maximal inspiration
Vital capacity
Volume of air in lungs after maximal inspiration
Total Lung capacity
Anatomic dead space of conducting airways + functional dead space in alveoli; volume of air not apart of gas exchange
Physiologic Dead Space
Largest contributor of physiologic dead space
Apex of Lung
Total Volume of gas entering the lung per minute
Minute ventilation
Volume of gas per unit time that reaches the alveoli
Alveolar ventilation
When inward pull of lung is balanced by outward pull of chest wall, and systemic pressure is atmospheric
FRC
When airway and alveolar pressures are 0; intrapleural pressure is negative
FRC
Change in lung volume for a given change in pressure
Compliance
Causes of decreased lung compliance
Pulmonary fibrosis, pneumonia, pulmonary edema
Causes of increased lung compliance
Emphysema and aging
Taut/tense Hb
Low affinity for oxygen (tissues)
Relaxed Hb
High affinity for oxygen (lungs)
Hb biochemistry
Positive cooperativity and negative allostery
Right Shift
Increase chloride, H, CO2, 2,3-BPG, temperature, taut Hb
leads to increases O2 unloading
Left Shift
Relaxed, higher affinity for oxygen; Fetal Hb (b/c lower affinity for 2,3BPG than adult); CO poisoning
Oxidized form of Hb (3+)
Methemoglobin; decreased affinity for O2
Cyanosis and chocolate colored blood
Methemoglobin
Tx of cyanide poisoning
Nitrates first to oxidize Hb to Met-Hb which binds cyanide; use thiosulfate to bind cyanide making thiosulfate which is renally excreted
Carbon Monoxide
200x greater affinity for Hb than oxygen
Cause of sigmoidal shape of Hb dissociation curve
Positive cooperativity
Why myoglobin curve is not sigmoidal
No positive cooperativity; monomer not a tetramer like Hb
Low resistance, high compliance system
Pulmonary circulation
Consequence of pHTN
cor pulmonale; right ventricular failure (JVD, edema, hepatomegaly)
Diffusion Limited
emphysema and fibrosis; Gas does not equilibriate by the time blood reaches the end of capillary
Hypoxemia with normal A-a gradient
high altitude and hypoventilation
Hypoxemia with increased A-a gradient
V/Q mismatch; diffusion limitation; right-to-left shunt
V/Q at apex of lung
3; wasted ventilation
V/Q at base of lung
0.6; wasted perfusion
PA > Pa > Pv
Apex of lung; decrease ventilation and very decreased perfusion causing increase in V/Q ratio
Pa > PA > Pv
Zone 2; middle of lung
Pa > Pv > PA
Base of lung; increase in ventilation but very increased perfusion causing a decrease in V/Q ratio even though increase in blod ventilation and perfusion overall
V/Q = 0
airway obstruction (shunt); 100% oxygen does not improve pO2
V/Q = infinity
blood flow obstruction (physiologic dead space); 100% oxygen does improve pO2
Highest CO2 transportation
HCO3- (90%)
Carbaminohemoglobin
HbCO2; CO2 bound to Hb at the N-terminus
CO2 favors taut Hb; (5%)
Dissolved CO2
5% CO2 travels to lungs in this form
Haldane effect
Oxygenation leads to H+ dissociation, shifting equilibrium to CO2 formation; CO2 released from RBCs in lungs
Bohr Effect
Increased H+ from tissue metabolism shifts curve to the right; unloads O2 to tissues
Ventilatino response to high altitude
Chronic increase ventilation
Cellular changed in response to high altitude
increase 2,3-BPG to release more oxygen; increase mitochondria; increase erythropoietin an dincrease renal excretion of HCO3-
PaO2 and PaCO2 in response to exercise
NO CHANGE; only change is in the venous system
V/Q ratio during exercise
from apex to base; more uniform because increase ventilation rate to meet O2 demand
