Respiratory Physiology Flashcards
Volume of air inspired or expired with each normal breath?
Tidal volume
Air that cans still be breathed in after normal inspiration?
Inspiratory Reserve Volume
Air that can still be breathed out after a normal expiration?
Expiratory Reserved Volume
Air in the lung after maximal expiration?
Residual Volume
Air that can be breathed in after normal expiration?
Inspiratory Capacity
Air that remains in the lungs after a normal expiration?
Functional Residual Capacity
Marker of lung function?
Functional Residual Capacity
Maximum volume of gas that can be expired after a maximal inspiration?
Vital Capacity
Volume of gas present in the lungs after a maximal inspiration?
Total Lung Capacity
Volume of air utilized for continual gas exchange to occur between breaths?
Residual Volume
Lung volume that can not be measured by spirometry?
Residual Volume
What is the effect on resistance and airflow if there’s a decreased airway radius by a factor of 4 ?
By the Poiseuille Law, radius is raised to the fourth power.
-Resistance will increase by a factor of 256 and airflow will decrease by a factor of 256. (Poiseuille Law)
What lung disease?
Low FEV1
Low FVC
FEV1<FVC 📍
High FRC 📍
Obstructive Lung Disease : Asthma or COPD
What lung disease?
Low FEV1
Low FVC
FEV1<FVC
High FRC
Normal DLCO 📍
Asthma
What lung disease?
Low FEV1
Low FVC
FEV1<FVC
High FRC
Low DCLO 📍
COPD
What lung disease?
Low FEV1
Low FVC
FEV1>FVC📍
Low FRC 📍
Restrictive Lung Disease
Where is this formula used?
PO2 x Solubility of O2 in blood = _____________
Dissolved gases
What happens to the net diffusion of O2 when the partial pressures of O2 in alveolar air and pulmonary capillary are equal?
There is no more net diffusion of O2 ( Ficks Law)
Expected alveoli finding in an infant born prematurely with neonatal respiratory distress syndrome?
Collapse of the small alveoli
Surfactant appears between 24th and 35th gestational week. In the absence of surfactant , surface tension is too high , the small alveoli will collapse into larger alveoli.
Hypoxia causes vasoconstriction in this vascular bed?
Pulmonary
12/M cyanotic, had a severe asthmatic attack with arterial PO2 of 60mmHg and PCO2 of 30mmHg. What is the explanation for low PCO2?
His arterial PCO2 Is lower than normal because hypoxemia is causing him to hyperventilate.
12/M cyanotic, had a severe asthmatic attack with arterial PO2 of 60mmHg and PCO2 of 30mmHg. What is the drug classification of the treatment ?
B2 adrenergic agonist
Intrapleural pressure level during inspiration?
Intrapleural pressure is more negative than it is during expiration.
Volume that remains in the lungs after a tidal volume is expired?
Functional Residual Capacity
35/M with this following lung volumes, what’s the ERV?
VC: 5L
TV: 0.5 L
IC: 3.5 L
FRC: 2.5L
1.5 L
ERV= VC - IC
Blood flow in the lungs when a person is standing is highest where?
Highest at the base because that is where the difference between arterial and venous pressure is greatest.
What happens to the FRC during atmospheric pressure?
When an airway pressure is equal to the atmospheric pressure, it is designated as zero pressure.
- when the airway pressure is zero ( atmospheric) , the volume of the combined system is the functional residual capacity.
Site of highest airway resistance?
Medium sized bronchi
49/M with pulmonary embolism and with complete blocked blood flow to his left lung. Effect on alveolar PO2 of the left lung?
Alveolar PO2 in the left lung will be approximately equal to the PO2 in inspired air.
- this is because there is no blood flow to the left lung , and no gas exchange between the alveolar air and pulmonary capillary blood.
Strenuous exercises causes a shift from where ?
Shift from curve A to curve B
aka
Shift to the right; Increased unloading of O2, decreased affinity of O2
Effect on P50 when there’s a shift from curve A to curve B / shift to the right?
Increased P50
Volume remains in the lungs after a maximal expiration?
Residual volume
Resistance in the pulmonary circulation compared to systemic circulation?
Lower resistance
- blood flow or cardiac output is nearly equal. Pulmonary circulation is characterized as having both lower pressure and resistance.
65/M compute for the alveolar ventilation with the following values:
TV: 0.45L
RR: 16
Arterial PCO2 : 41
Expired PCO2: 35
6.14 L/ min
- Alveolar ventilation is the difference between tidal volume and dead space multiplied by breathing frequency.
- Dead space= 0.45 x (41-35/41) = 0.066L
- Alveolar ventilation = (0.45L- 0.066L) x 16bpm = 6.14 L/min
PCO2 at the base of the lungs compared with the apex ?
Higher pulmonary capillary PCO2
Hypoxemia produces hyperventilation by a direct effect on the __________ and ____________.
Carotid & Aortic body chemoreceptors
Vs
Medullary chemoreceptors which which are stimulated by CO2 or H+
Effect of strenuous exercise on ventilation rate and O2 consumption together ?
Ventilation rate and O2 consumption increases to the same extent
Pulmonary capillary in an area of a lung not ventilated will have PO2 that is equal to what?
Equal to mixed venous PO2
- If an area of the lung is not ventilated , there can be no gas exchange in that region. The pulmonary capillary blood serving that region will not equilibrate with alveolar PO2 but will have a PO2 equal to that of the mixed venous blood.
Occurs in the venous blood during CO2 transport from tissues ?
Conversion of CO2 and H2O to H+ and HCO3 in the red blood cells.
Occurs in the venous blood during CO2 transport from tissues.
Conversion of CO2 and H2O to H+ and HCO3 in the red blood cells (RBCs)
Diseases with hypoxia, with decreased arterial PO2 and an increased A-a gradient. (3)
- R-L cardiac shunt
- V/Q defect
- Fibrosis
42/F with severe pulmonary fibrosis
ABG
pH : 7.48
PaO2: 55
PCO2: 32
What’s the explanation for PaCO2?
The decreased PaO2 stimulates breathing via peripheral chemoreceptors.
38/F moved to Colorado 10,200 feet above sea level. What will happen to the Hgb-O2 curve?
Shift to the right .
At high altitudes, PO2 of alveolar air is decreased and hypoxemia occurs causing hyperventilation and respiratory alkalosis , 2-3BPG also increases adaptively.
The pH of venous blood is only is only slightly more acidic than the pH of arterial blood because?
The H+ generated from CO2 and H2O is buffered by deoxyhemoglobin in venous blood.
Total volume expired in maximal expiration?
Vital Capacity or FVC
In which V/Q defects is supplement O2 beneficial?
Low V/Q
Regions with low V/Q have the highest blood flow. Thus, breathing high PO2 air will raise the PO2 of a large volume of blood and have the greatest influence on the total blood flow leaving the lungs.
48/F breaths a gas mixture containing 21% O2. What is the cause of her hypoxemia?
ABG
PaO2= 60 mmHg
PaCO2= 45 mmHg
Normal DLCO
Choices:
a. Carbon monoxide poisoning
b. Fibrosis
c. R-L shunt
R- L Shunt
- Carbon monoxide should have a decreased O2 content of blood but would not have an decreased PaO2. Not hypoxemic.
- Fibrosis should have a low DLCO and is usually a diffusion defect.
- Calculation of A-a gradient:
PIO2 = (760mmHg- 47 mmHg) x 0.21 = 150mmHg
PAO2= 150mmHg -45 mmHg / 0.8 = 94 mmHg
A-a gradient = 94mmHg - 60mmHg = 34mmHg , which is increased and consistent with right to left shunt
62/ M breaths a gas mixture containing 21% O2. Cause of her hypoxemia?
ABG
PaO2 = 60mmHg
PaCO2= 70mmHg
Choices:
a. R-L shunt
b. Fibrosis
c. Hypoventilation
Hypoventilation
PaCO2 of 70mmHg
Formula of Physiologic Deadspace ?
Physiologic Dead Space = Anatomic Dead space + Alveolar Dead space
Alveolar Dead space = TV x [(PaCO2- PECOs)/ (PaCO2)]
Associated with Barrel-Chest?
Emphysema ( Increased lung compliance, Increased FRC)
V. cholerae causes diarrhea because?
It increasses Cl- secretory channels in Crypt Cells
What is the alveolar ventilation?
VT 0.45L
Arterial PCO2 41mmHg
PCO2 of expired air 35mmHg
RR 16
Alveolar ventilation computation:
6.14 L
Marked by high respiratory drive + Abnormal compliance
( Not Specific to COVID-19)
COVID-19
Drugs that can cause interstitial lung disease / restrictive lung disease. (3)
- Busulfan
- Amiodarone
- Methotrexate
Microscopic crystals composed of eosinophil protein galectin -10
Charcot- Leyden Crystals
Charcot- Leyden Crystals are seen in? (2)
Asthma & Parasitic Pneumonia
Main pressure that moves fluid from capillaries to pulmonary interstitium?
Capillary Pressure
Rupture of the alveolar walls occur at ____________.
Any positive pressure in the interstitial spaces greater than alveolar pressure (>0mmHg) that causes dumping of fluid from the interstitial spaces to the alveoli.
Pulmonary edema can cause death by suffocation in 20-30 minutes in which scenario?
Severe acute left heart failure
What exerts the greatest pressure in mmHg to move fluid from capillaries to the pulmonary interstitium?
Pulmonary Capillary Hydrostatic Pressure (+7mmHg)
Location of defective alveolar walls in patients with emphysema. (2)
Panacinar emphysema - more severe in lower lobes.
Centroacinar emphysema- more severe in upper lobes.
CUPL
In patient rapidly breathing due to asthma , we expect?
Lower than normal arterial PCO2 because hypoxemia triggers hyperventilation.
Drug we give to patients with asthma?
Beta 2 Adrenergic Agonist (B-2 Agonist)
Characterizes asthma ? (4)
- Bronchoconstriction ( spastic contraction of bronchiolar smooth muscles)
- Increased mucus production
- Problem with expiration rather than inspiration
- FRC increased during asthma attack
High in patients with asthma?
IgE
Air in the lungs after expiring Tidal volume ?
FRC
Normal Pulmonary Arterial Pressure (PAP) ?
15-25 / 8-10 mmHg
Normal ratio of systemic to pulmonary pressure?
0.125694444
Decreases O2 affinity? (5)
- Inc CO2
- Acidosis
- Inc 2,3-BPG
- Exercise
- Inc Temperature
CABET do the RIGHT thing, Let go.
Muscles for breathing used by runner?
Forced Inspiration ( Occurs during exercise)
1. External Intercostals
2. Accessory Muscles : (6)
SCM, ANT SERRATI, SCALENE, ALA NASI, GENIOGLUSSUS , ARYTENOID
Forced Expiration ( Occurs during exercise)
1. Internal Intercostals
2. Abdominal muscles : (4)
RECTUS ABDOMINIS , INTERNAL AND EXTERNAL OBLIQUE, TRANSVERSUS ABDOMINIS
Accessory Muscles used in Forced Inspiration? (6)
Accessory Muscles : (6)
SCM, ANT SERRATI, SCALENE, ALA NASI, GENIOGLUSSUS , ARYTENOID
Abdominal Muscles used for Forced Expiration? (4)
Abdominal muscles: (4)
RECTUS ABDOMINIS , INTERNAL AND EXTERNAL OBLIQUE, TRANSVERSUS ABDOMINIS
Location of bronchial Kulchitsky cell ( pulmonary neurondocrine cells).
Basement membrane of bronchi and bronchioles
Characteristics of Type I pneumocytes? (4)
Thin, Flat , For gas exchange, Does not secrete surfactant.
Pressure in the pulmonary veins is equal to the pressure in _____________.
PCWP ( Pulmonary Capillary Wedge Pressure)
Hyperventilation causes which acid -base abnormality?
Respiratory Alkalosis
Formula for PAO2 ?
PAO2 = (FiO2 x (Patmos-PH2O))- (PaCO2/RespQ)
Formula for Capacitance?
C=V/P
Thermoregulatory centers for heat loss and heat conservation respectively:
Heat Loss: Anterior
Heat Conservation: Posterior
What is the purpose of brown bag in hyperventilation?
Increase PaCO2
Stimulation of Beta-2 receptors in the lungs will cause?
Bronchodilation
Blood pathway from pulmonary vein? (14)
- Pulmonary Vein
- Left atrium
- Left Ventricle
- Aorta
- Other arteries
- Arterioles
- Capillaries
- Veins
- SVC / IVC
- Right atrium
- Right Ventricle
- Pulmonary Artery
- Pulmonary Arteriole
- Pulmonary Capillaries
I+T+E ?
VC
Living in high altitude can cause?
Shift to the right O2 - Hgb dissociation curve
Bronchiole capable of gas exchange?
Respiratory bronchiole
Last bronchiole not capable of gas exchange?
Terminal bronchioles
Inhalation through nostrils vs mouth?
Better air conditioning if through nostrils
- humidification and warming occurs as air enters
Respiratory quotient increases in?
High carbohydrate diet