Respiratory Physiology Flashcards
Three Values that cannot be measured using spirometry
FRC, RV and TLC
Formula for pressures of the lung
P_A = P_Pl + P_L
What happens to the FEV1/FVC ratio with obstructed lung disease (i.e. asthma)
Ratio decreases because FEV1 decreases much more than FVC
What happens to the FEV1/FVC ratio with fibrosis of the lung
Ratio will stay the same or will increases because of the large change in BOTH FEV1 and FVC
Minute Ventilation Formula
V_E = TV * RR
Alveolar Ventilation
V_A = (V_T - V_D) * RR
Definition of FRC
When the internal elastic recoil of the lung is equal to the outward force of the chest wall
Compliance of the chest/ lung system is () than that of the lungs alone or the chest wall alone
Compliance of the system is LESS THAN either one alone, due to the flatness of the curve
What happens to lung and chest wall upon a pneumothorax
Air enters the pleural space causing the lung to collapse (+ P_Pl) and the chest wall spring outward
Result of Emphysema on FRC
Emphysema increases compliance of the lungs (lungs are more floppy). Tendency for lungs to collapse decreases.
Lung chest wall system reaches new HIGHER FRC for lungs to have equal opposing force
Result of Fibrosis on FRC
Fibrosis decreases compliance of the lungs (lungs are more rigid). The lung-chest wall system will go towards a lower FRC, so that the lungs have less of a expanding force acting upon them.
Major Site of airway resistance
Medium sized bronchi
NOT smaller airways because of parallel arrangement
Sympathetic mechanism and results
Lung activated by Beta 2
Cause bronchodilation
Balloon catheter in the esophagus measures
P_Pl
Intrapleural pressure
What state of Iron does Oxygen bind to?
Fe2+ found in Hemoglobin
Hemoglobin is made up of ____ subunits, each of which contain a _____ moiety
Hemoglobin is made up of 4 subunits that each contain a Heme moiety
Difference between fetal and adult hemoglobin
Fetal hemoglobin has 2 gamma chains that replace the 2 beta chains in the adult. These gamma chains increase oxygen affinity for of fetal hemoglobin
Mechanism for increased oxygen affinity in fetal hemoglobin
gamma chains do not interact as well with 2,3 DPG.
2,3 DPG promotes oxygen release from hemoglobin
Iron state in methmoglobin
Iron is in ferric Fe3+ state
Does not bind O2
Right Shift of Hemoglobin and result of P50
i.e. makes it easier for unloading of O2 low pH high CO2 High 2,3 DPG High Temp P50 is increased
2,3 DPG binds to which part of hemoglobin
beta chains of deoxyhemoglobin
Left Shift of Hemoglobin and result of P50
i.e. makes it harder for unloading of O2 high pH low temp low CO2 low 2,3 DPG presence of CO increases P50
Three ways to transport CO2 in the blood
- Dissolved CO2
- Carbaminohemoglobin, CO2 bound to hemoglobin
- HCO3-
NB: HCO3- is major form of CO2 in the blood (~90%)
How does HCO3- leave the RBC?
Cl- antiporter
Cl- into the cell, HCO3- out of the RBC
Zone 1 of Lung
P alveoli > P arteriole > P Vein
When standing blood flow is lowest in this area
Zone 2 of Lung
P arteriole > P alveoli > P Vein
P arteriole increases due to gravity effect on hydrostatic pressure
Blood flow driven by P arteriole - P alveoli
Zone 3 of Lung
P arteriole > P vein > P alveoli
blood flow driven by arterial and venous pressure
Hypoxia in the lung causes _______
vasoconstriction
Left to right shunts result in ______ Po2 of right atrial blood
Increased PO2 of right atrium with no change in left atrial PO2
Factors effecting V/Q
- Frequency of Breath
- Tidal Volume
- Cardiac OUtput
NB: NL V/Q = 0.8, PO2 = 100 mmHg, PCO2 = 40 mmHg
Blood flow is lowest at the ______ and greatest at the _____ in the lung
blood flow is greatest at the base and lowest at the apex
Ventilation is lowest at the ______ and greatest at the ______ in the lung
Ventilation is greatest at the base and lowest at the apex however the difference is not that great.
Which has the greatest V/Q ratio, the apex of the lung or the base?
Apex has larger V/Q because of smaller Q
both Apex and Base have similar ventilation (V)
What is the V/Q ratio when the trachea is obstructed by a piece of steak? What happens to A-a gradient?
With normal blood flow, V = 0
Thus V/Q = 0
A-a gradient increases
What is the technical term when V/Q = 0
This is a physiological shunt
What is the V/Q ratio in the presence of a pulmonary embolism?
No blood flow in that region of the lung, so the V/Q ratio approaches infinity.
When V/Q is infinite, this is called
Dead space
Sensory information of PCO2, lung stretch, irritants is cordinated in the ______
brainstem
Medullary Respiratory Center is located in the _______
Reticular Formation
Dorsal Respiratory Center of Reticular Formation responsible for
Inspiration and generates basic rhythm for breathing
INput: vagus and glossopharyngeal nerves
OUTput: phrenic nerve
Ventral Respiratory Group
Primarily responsible for expiration
not active during normal quiet breathing
actived during exercise i.e. active expiration
Function of lower pons in breathing
Stimulates breathing
Apneustic = large inspiratory breath
Function of upper pons in breathing
Inhibits breathing
Pneumotaxic
Central Chemoreceptors location and stimulants
Located in the medulla
decrease in pH and increase in CO2 stim breathing
Peripheral Chemoreceptors location and stimulants
Carotid Bodies, Aortic bodies
PO2 drop (<60mmHg)
pH drop
increase in CO2
Hering-Breuer Reflex
Increase in stretch receptors within the smooth muscle of the lungs causes a decrease in breathing frequency
What happens to mean values of PO2 and PCO2 during exercise
The values DO NOT CHANGE
What happens to venous PCO2 during exercise?
Venous PCO2 increases during exercise
