Respiratory System Flashcards
The relaxation and dilation of the upper airways is a function of the ___________ (sympathetic or parasympathetic) branch of the autonomic nervous system, mediated by ___________ (neurotransmitter) binding to ___________ (receptor type) receptors.
sympathetic, epinephrine/norepinephrine, adrenergic (β2)
___________ is the medical term for the total rate of air movement into and out of the lungs.
ventilation
___________ law states that the product of pressure and volume is constant, a relationship that helps explain how pressure changes in the lungs drive breathing.
Boyle’s
___________ volume refers to the volume of air breathed in and out during a normal breath, while ___________ volume represents the additional volume of air that can be forcibly inhaled after a normal inhalation.
Tidal, inspiratory reserve
The majority of gas exchange occurs in the ________.
alveolar sacs
Smoking affects the ______ lobes of the lung the most.
upper
The ___________ are tiny sacs in the lungs where gas exchange takes place, primarily mediated by ___________ cells.
alveoli, Type I
While Type I alveolar cells are primarily responsible for gas exchange, ___________ cells within the alveoli are crucial for fluid reabsorption and the secretion of ___________, a substance that reduces surface tension and prevents alveolar collapse.
Type II, surfactant
True or False: sympathetic innervation of the airways leads to dilation.
True
Albuterol acts at _____ receptors.
Beta-2
True or False: The back of the trachea has collagen rings.
False (C-shape allows for both expansion of trachea and protection)
___________ refers to the total volume of the lung that does not participate in gas exchange, including the anatomical dead space of the conducting airways and any alveolar volume that is not adequately perfused.
Physiologic dead space
The conducting zone consists of: ________
Trachea, bronchi
True or False: No gas exchange occurs in the conducting zone.
True
The forced expiratory volume in 1 second (FEV1) divided by the forced vital capacity (FVC) is approximately ___________ in healthy individuals, and a value below this threshold suggests ___________.
0.8, obstructive lung disease
Increase the velocity of air may aid in _______.
coughing
Bronchioles, unlike the alveoli, primarily engage in fluid ___________ (secretion or reabsorption), driven by the movement of ___________ ions through epithelial cell ___________ channels.
secretion, Cl-, CFTR
The aqueous layer on top of the luminal layer of the alveolar cells is very ______.
thin
CFTR stands for _______.
Cystic Fibrosis Transmembrane Conductance Regulator
In the context of pulmonary physiology, ___________ refers to the process of air reaching the alveoli, while ___________ refers to the blood flow in pulmonary capillaries that allows for gas exchange.
ventilation, perfusion
The partial pressure of oxygen (PaO2) in arterial blood is typically ___________ (higher or lower) than the partial pressure of oxygen in the alveoli (PAO2).
lower
An increase in the physiological dead space will ___________ (increase or decrease) the efficiency of gas exchange in the lungs.
decrease
During exercise, alveolar ventilation ___________ (increases or decreases) to meet the increased demand for oxygen uptake and carbon dioxide removal.
increases
The shape of alveolar Type I cells is _______, while Type II is more _______.
squamous, cuboidal
Normal breathing is referred to as _____.
tidal volume (TV)
Vital capacity is ______.
The summation of IRV and ERV.
FEV1 is the amount of air able to be _______ in one second.
expired
True or False: residual volume is able to be measured by simple spirometer.
False, you can’t get all the air out of your lungs because they will collapse
Constriction of the bronchioles, as seen in asthma, primarily affects ___________ (airway resistance or lung compliance) and leads to ___________ (increased or decreased) airflow.
airway resistance, decreased
The volume of air remaining in the lungs after a maximal exhalation is called the ___________.
residual volume
Common way of measuring RV nowadays is _____.
helium dilution
Average total ventilation for an adult is _____ ml/min.
7500
Average alveolar ventilation for an adult is ______ ml/min.
5250
Minute ventilation is tidal volume x _________.
breaths per minute
Inspired air is approximately ______ mmHg.
150
Mixed venous blood has (in terms of partial pressure) approximately ______ mmHg oxygen and ______ mmHg CO2.
40, 46
Horseshoe crabs have ______ instead of iron in the middle of hemoglobin.
copper
The byproduct of RBC glycolysis that affects oxygen dissociation is ________.
23DPG
The metal ion at the center of the heme group in hemoglobin is ______.
Iron (Fe)
The effect that describes the influence of pH and CO2 on oxygen binding to hemoglobin is the __________.
Bohr Effect
The effect that describes the influence of oxygen on CO2 binding to hemoglobin is the _________.
Haldane Effect
The approximate percentage of oxygen transported in the blood that is dissolved in plasma is _______.
15
The protein responsible for the majority of oxygen transport in the blood is __________.
hemoglobin
One molecule of hemoglobin can bind _____ oxygen molecules.
4
The condition where the iron in hemoglobin is oxidized to Fe3+ and cannot bind oxygen is ____________.
Methemoglobinemia
The partial pressure of oxygen PO2 in arterial blood is approximately ________.
100 mmHg
The partial pressure of oxygen PO2 in mixed venous blood is approximately _________.
40 mmHg
The approximate oxygen saturation of arterial blood is _____.
98
The approximate oxygen saturation of mixed venous blood is _____.
75
The graph that shows the relationship between oxygen partial pressure and hemoglobin saturation is the _____________.
Oxygenhemoglobin dissociation curve
The shape of the oxygen-hemoglobin dissociation curve is ________.
Sigmoidal
A rightward shift of the oxygen-hemoglobin dissociation curve is caused by ___________.
Increased temperature, Increased PCO2, Increased 23DPG, Decreased pH
A leftward shift of the oxygen-hemoglobin dissociation curve is caused by ____________.
Decreased temperature, Decreased PCO2, Decreased 23DPG, Increased pH
The P50 value is ______________.
The partial pressure of oxygen at which hemoglobin is 50 saturated
The effect of increased 23DPG on oxygen affinity of hemoglobin is ____________.
Decreased affinity
Conditions that can lead to increased 23DPG levels are ________.
Hypoxia, High altitude
Fetal hemoglobin differs from adult hemoglobin in terms of 23DPG binding because _____________.
Fetal hemoglobin binds 23DPG less avidly
The approximate affinity of carbon monoxide CO for hemoglobin compared to oxygen is _______________.
250 times greater
The molecule formed when carbon monoxide binds to hemoglobin is __________.
Carboxyhemoglobin
The effect of carbon monoxide binding on the oxygen-hemoglobin dissociation curve is _________.
Leftward shift making it harder to unload oxygen
The term for insufficient oxygen supply to tissues is ________.
hypoxia
The transcription factor that is activated in response to hypoxia is _____________.
Hypoxiainducible factor 1a (HIF1a)
The hormone stimulated by HIF1a to increase red blood cell production is ___________.
Erythropoietin EPO
Erythropoietin EPO is produced in the __________.
kidneys
The main form in which CO2 is transported in the blood is __________.
Bicarbonate (HCO3)
The enzyme that catalyzes the conversion of CO2 and water to carbonic acid is ________.
Carbonic anhydrase
The membrane protein that exchanges bicarbonate for chloride ions across the red blood cell membrane is _________.
Anion exchanger 1 (AE1) or Chloride-bicarbonate exchanger
The effect the binding of oxygen to hemoglobin has on CO2 transport Haldane effect is ____________.
It promotes the release of CO2 from hemoglobin
The effect the binding of CO2 to hemoglobin has on oxygen transport Bohr effect is ___________.
It promotes the release of oxygen from hemoglobin
During exercise, the oxygen-hemoglobin dissociation curve shifts __________.
rightward
At high altitude, the oxygen-hemoglobin dissociation curve shifts ___________.
rightward
The effect of exercise on oxygen consumption is _____________.
increased oxygen consumption
The effect of high altitude on oxygen availability is ___________.
decreased oxygen availability
The main physiological adaptations to high altitude are __________.
Increased ventilation, Increased red blood cell production, Increased 23DPG levels
The primary function of the respiratory system is ____________.
Gas exchange: oxygen uptake and carbon dioxide removal
The two main components of the respiratory system are _________ and _______.
lungs, airways
The tiny air sacs in the lungs where gas exchange occurs are the __________.
alveoli
The muscle that separates the thoracic cavity from the abdominal cavity and is involved in breathing is the ________.
diaphragm
During inhalation, the volume of the thoracic cavity _________.
increases
During inhalation, the pressure in the thoracic cavity ________.
decreases
The law that describes the relationship between pressure and volume of a gas is _________.
Boyle’s law
The pressure gradient that drives oxygen from the alveoli into the blood is the ______________.
partial pressure gradient
The pressure gradient that drives carbon dioxide from the blood into the alveoli is the ______________.
partial pressure gradient
The typical breathing rate at rest is ___________.
1220 breaths per minute
The condition where breathing is difficult or labored is _______________.
dyspnea
The condition where breathing stops temporarily during sleep is _______________.
sleep apnea
The most common expressed protein in a red blood cell is __________, which is “band 3” on a western blot.
AE1
True or False: Carbon dioxide and water going bicarb and protons always requires carbonic anhydrase.
False
What are the four components of the respiratory control system?
- Chemoreceptors, 2. Mechanoreceptors, 3. Brain Stem (medulla & pons), 4. Respiratory muscles
What part of the brain provides voluntary control of respiration?
Cerebral Cortex (But, ‘overruled’ by Brain Stem)
What is apneusis?
Sustained effort for inhalation unrelieved by exhalation
True or False: The pons is the most essential portion of the brain needed for respiration.
False, it’s the medulla
What is the function of the pneumotaxic center?
Sends inhibitory impulses on inspiration, preventing overdistension of the lungs
Smooth, steady inspiration due to ramp signals allows for _________(less/more) work by the respiratory system.
Less, smaller pressure gradient
True or False: Smooth, steady expiration prevents the lungs from collapsing.
True
What nerve innervates the diaphragm?
Phrenic nerve
What nerve innervates the tongue muscles (except palatoglossus)?
Hypoglossal nerve
Describe the diaphragm’s electroneurographic activity during normal inspiration.
Begins weakly and increases steadily in a ramp manner for about 2 seconds.
What is the primary method for controlling the rate of respiration?
Changing the rate of increase of the ramp signal in the diaphragm
What is the function of the inspiratory “off-switch” signal?
Offsets the large elastic recoil of the lungs at the end of inspiration
True or False: Central chemoreceptors directly measure Pco2.
False, they measure it indirectly by measuring pH (H+ ions)
Define eupnea
Normal, good, unlabored ventilation
Describe the breathing pattern in apneustic breathing.
Protracted gasping inhalation followed by short, inefficient exhalation
In terms of the respiratory gases and reactions, _____ can pass the BBB, but _______ and ________ cannot.
CO2, H+ and HCO3-
What can cause apneustic breathing?
Damage to the vagus nerve or pneumotaxic center, or drugs like ketamine
What is the leading cause of central sleep apnea syndrome (CSAS)?
Instability in the feedback control involved in the chemical regulation of breathing
What is the typical breathing pattern during cardiac arrest?
Gasping (Causes include cerebral ischemia, extreme hypoxia, or anoxia)
What causes ataxic breathing?
Damage to the medulla oblongata
Chemoreceptors are _____ Type I cells.
glomus
The net pressure for air movement is calculated as ___________. A negative value indicates air flows ______(in/out), while a positive value indicates air flows _____(in/out).
Pnet = Palv – Patm, in, out
__________ refers to the distensibility of the lung.
Compliance
On a pressure-volume loop, the slope represents ________.
compliance
The difference between inflation and deflation routes on a pressure-volume loop is called __________.
hysteresis
In the pressure-volume loop for an isolated lung, hysteresis is eliminated when ___________ is eliminated.
surface tension
At functional residual capacity, the pressure in the lung-chest wall system is ____.
0
Emphysema increases lung compliance, leading to a ________(higher/lower) FRC.
higher
Fibrosis decreases lung compliance, leading to a ________(higher/lower) FRC.
lower
Floppy lungs seen in emphysema make airways more prone to collapse during _________.
expiration
Surface tension is the force that acts to pull a liquid’s surface molecules together at the __________.
air interface
According to Laplace’s Law, the pressure inside a sphere is equal to ______, where T represents surface tension and r represents the radius.
2T/r
Smaller alveoli tend to ________ into larger ones.
collapse
________ prevents the collapse of smaller alveoli.
Surfactant
Most of the elastic recoil in a normal lung is due to ___________.
surface tension
Surfactant is a complex mixture of ________.
lipoprotein
Surfactant reduces surface tension, elastic recoil, and effort to inflate, ultimately ___________ compliance.
increasing
The hereditary absence of the surfactant protein ______ is fatal.
SP-B
Approximately ______ of surfactant is lipid, with about half of that being DPPC.
90%
The synthesis and expression of surfactant is low until ______.
birth
The two implications of Laplace’s law in premature births are reduced collapsing pressure in ____________ and increased lung ___________, leading to a reduction in the work of breathing.
small alveoli, compliance
Poiseuille’s Law relates airflow to the pressure difference and _________ of the airways.
resistance
__________ lowers the surface tension of water, increasing compliance.
Surfactant
Increased bronchiolar __________ leads to less airway resistance.
diameter
_________ is characterized by intermittent attacks in which airway smooth muscle contracts.
Asthma
__________ involves the destruction of alveolar walls and loss of pulmonary capillaries.
Emphysema
____________ involves excessive mucus production in bronchi and inflammatory changes in small airways.
Chronic bronchitis
Airway resistance is greatest at ___________ and decreases steeply as lung volume increases.
residual volume
Changes in compliance shift volume for any given pressure difference, thus affecting __________.
airway resistance
During inspiration, the ___________ move upward and outward.
lower ribs
Normal expiration occurs via the _________ of inspiratory muscles.
relaxation
The main muscle of inspiration is the _________.
diaphragm
The ______________ are accessory muscles of inspiration.
external intercostals
The ___________, ____________, and __________ are muscles of forced expiration.
internal intercostals, external oblique, rectus abdominis
During forced expiration, the contraction of expiratory muscles increases ________.
Pip
In emphysema, diminished elastic recoil leads to a lower ___.
Ptp
Forced expiration in individuals with emphysema can lead to ______________.
airway collapse
At the beginning of inspiration, the pressure difference (Δ) between the alveoli and the atmosphere is ______.
25-20
At the end of inspiration, the pressure difference (Δ) between the alveoli and the atmosphere is ______.
15-20
During the respiratory cycle, when airflow is 0, forces are ________.
balanced
The transpulmonary pressure (Ptp) is calculated as _________.
Palv - Pip
To calculate alveolar pressure (Palv), use the equation: __________.
Palv = Ptp + Pip
An increase in tidal volume ________(increases/decreases) ventilation.
increases
An increase in breathing rate ________(increases/decreases) ventilation.
increases
A decrease in tidal volume __________(increases/decreases) ventilation.
decreases
A decrease in breathing rate __________(increases/decreases) ventilation.
decreases
Lung ‘collapse’ pressure is represented by ____.
Ptp
Chest wall ‘expand’ pressure is represented by _____.
-Pcw
Greater pressure difference for a similar volume change results in ________.
more work
The process of _________ is crucial for gas exchange in the lungs.
diffusion
A typical individual consumes approximately 250 ml/min of ____.
O2
The production of _____ in a typical individual is around 200 ml/min.
CO2
When describing gas in the gas phase, the abbreviation ______ is used, which stands for body temperature, ambient pressure, and saturation with water vapor.
BTPS
_____ which stands for standard temperature, standard pressure, and dry gas, is used to describe gas in the liquid phase.
STPD
To convert gas volume from BTPS to STPD, the following equation is used: Gas volume at BTPS * 273/310 * (PB - 47)/760 = __________.
Gas volume at STPD
__________ is represented by the symbol PB.
Barometric pressure
At a temperature of 37°C, the water vapor pressure is ___ mmHg.
47
________ states that there is an inverse relationship between pressure and volume.
Boyle’s Law
In the airways, air undergoes __________.
humidification
The sum of the partial pressures of all gases in a mixture is equal to the total pressure, as stated by _______________.
Dalton’s Law of Partial Pressures
In dry air, the partial pressure of oxygen (PO2) is ________.
159.6 mmHg
The partial pressure of inspired oxygen (PIO2) is _______.
149.7 mmHg
At sea level, the atmospheric pressure is approximately ____ mm Hg and the atmosphere comprises about _____ oxygen.
760, 21%
Consequently, the PO2 at sea level is _____.
160 mmHg
The partial pressure of oxygen in the alveoli (PAO2) is typically _______.
105 mmHg
The partial pressure of carbon dioxide in the alveoli (PACO2) is normally _________.
40 mmHg
Under normal circumstances, the alveolar and arterial partial pressures of CO2 reach equilibrium, meaning ____________.
PACO2 = PaCO2
The relationship between a gas’s partial pressure and its concentration in a liquid is described by ___________.
Henry’s Law
According to Henry’s Law, Cx stands for the value of ________ in solution, excluding any __________.
free gas, bound gas
True or False: It is possible for two gases to have the same partial pressures but different dissolved concentrations.
True
______ Law provides a description of the diffusion of gases.
Fick’s
True or False: The driving force behind the diffusion of gases is the partial pressure difference (ΔP), not the concentration difference.
True
The diffusion coefficient (D) for CO2 is ____ times greater than that of O2.
20
For a given partial pressure difference, the diffusion rate of CO2 is 20 times _______(slower/faster) compared to O2.
faster
The lung O2 diffusion capacity (DL) is influenced by all parameters in Fick’s Law except for _____ and the time it takes for binding to hemoglobin.
ΔP
As per Fick’s Law, the rate of diffusion is directly proportional to the _________ and _______________ difference, while it is inversely proportional to the __________ of the barrier.
surface area, partial pressure, thickness
The partial pressures of both O2 and CO2 are influenced by _________ ventilation.
alveolar
The barriers that impede gas diffusion include the alveolar epithelium, _____________, and capillary endothelium.
interstitial space
The relationship between ___________ capacity and the resistance to diffusion in series is represented by the equation 1/DL = 1/DM + 1/(q*Vc).
diffusion
Although _______________ can be used to measure DL, it is important to use it at a low concentration for safety reasons.
carbon monoxide (CO)
Emphysema leads to a decrease in DL due to a reduced ___________.
surface area
An increase in the _________ of the diffusion barrier due to fibrosis results in a decrease in DL.
thickness
DL is reduced in pulmonary edema as a result of the increased thickness of the _________ barrier.
diffusion
________ causes a decrease in DL because of reduced hemoglobin levels.
Anemia
Under normal conditions, blood O2 achieves equilibrium with alveolar O2 within _________ of the capillary length.
one-third
Gases in solution can exist in three forms: dissolved gas, ________ gas, and chemically modified gas.
bound
_________ is unique among “air gases” in that it exists solely in dissolved form.
Nitrogen (N2)
The total concentration of a gas in solution is determined by the following equation: Total [gas] = [dissolved gas] + [bound gas] + [______________________].
chemically modified gas
The conversion of CO2 to bicarbonate is described by the equation CO2 + H2O ⇌ H2CO3 ⇌ HCO3- + ______.
protons (H+)
The ___________ of tissues is reflected in the partial pressure of CO2.
metabolic activity
A lower arterial PO2 can be attributed to __________.
shunt pathways
___________, which can arise in conditions like strenuous exercise and emphysema, can impact gas exchange.
Diffusion limitation
______________, which can occur under normal conditions, can affect gas exchange.
Perfusion limitation
___________ (Dt) refers to the duration available for gas exchange.
Contact time
Factors that can contribute to ____________ include decreased diffusion capacity, increased diffusion distance, increased perfusion rate, and decreased contact time.
diffusion limitation
_________________ can be influenced by factors such as increased diffusion capacity, decreased diffusion distance, decreased perfusion rate, and increased contact time.
Perfusion limitation
The capacity of blood to transport O2 can be compared to the capacity of _________, while blood flow is akin to _________.
rail cars, train speed
As one ascends to higher altitudes, the barometric pressure _________, but the fractional concentrations of individual gases remain ___________.
decreases, unchanged
The two main limitations of gas exchange are limitations due to the _______ process and limitations due to _______.
diffusion, blood flow
The symbol for ventilation is _______ and the symbol for perfusion is _______.
VA, Q
The ratio of ventilation to perfusion is represented as the _______ ratio.
VA/Q
Compared to the systemic circulation, the pulmonary circulation has _______ pressure and _______ resistance.
low, low
The pressure difference driving blood flow in the pulmonary system is approximately _______ mm Hg.
4
Pulmonary blood flow is regulated by altering the _______ of arteriolar smooth muscle via local vasoactive substances, primarily _______.
resistance, O2
A decrease in PAO2 below _______ mm Hg leads to _______ in the pulmonary vasculature.
70, vasoconstriction
Global vasoconstriction at high altitude results in an increase in total pulmonary _______ resistance.
vascular
The mechanism of hypoxic vasoconstriction involves the inhibition of _______ channels in smooth muscle cells.
K+
Bronchial circulation comprises a small fraction (around _______%) of left ventricular output.
2
The tracheobronchial tree receives systemic blood from the _______ circulation.
bronchial
Most of the blood from the bronchial circulation empties into the _______ vein, creating a “right-to-left shunt.”
pulmonary
The pulmonary circulation receives _______% of the cardiac output from the right ventricle.
100
Pulmonary blood flow is approximately equal to _______.
cardiac output
Blood flow through the heart and lungs follows this path: _______ → LV → systemic → RA → RV → pulmonary → _______ →.
LA, LA
An increase in alveolar transmural pressure gradient leads to an increase in _______, which has a significant impact on pulmonary vascular resistance (PVR).
alveolar volume
As alveolar volume (VL) increases, alveolar vessels experience an increase in _______ and a decrease in _______, leading to increased resistance.
length (L), radius (r)
Conversely, as lung volume increases, extra-alveolar vessels experience _________ resistance.
decreased
The volume at which pulmonary vascular resistance is at its lowest is _________________.
functional residual capacity (FRC)
An increase in cardiac output from the right ventricle leads to a _______ in pulmonary vascular resistance.
decrease
When lying down, blood flow distribution to the upper and lower regions of the lung is more _______.
even
Gravity causes blood flow per unit volume to be greater in the more _______ regions of the lung.
gravity-dependent
In a standing individual, alveolar pressure (PA) is _______ than arterial pressure (Pa) at the apex of the lung.
greater
In contrast, at the base of the lung in a standing individual, arterial pressure (Pa) is _______ than alveolar pressure (PA).
greater
Ventilation (VA) and perfusion (Q) are _______ at the top (zone 1) and _______ at the bottom (zone 3) of the lung.
low, high
Importantly, ventilation and perfusion do not change _______.
proportionally
Pulmonary blood flow is influenced by several passive factors, including _______, _______, and _______.
gravity, alveolar pressure, lung volume
In areas of the lung with ventilation but no perfusion, the PO2 will be _______ and the PCO2 will be _______.
high, low
Conversely, in areas with perfusion but no ventilation, PO2 will be _______ and PCO2 will be _______.
low, high
The apex of the lung has a _______ VA/Q ratio compared to the base.
higher
The normal VA/Q ratio for the entire lung is _______.
0.8
A normal VA/Q ratio results in a PaO2 of _______ mm Hg and a PaCO2 of _______ mm Hg.
100, 40
VA/Q mismatches can arise due to _______, _______, _______, and _______.
hypoventilation, ventilation of non-perfused regions, right-to-left shunts, left-to-right shunts.
Hypoventilation leads to _______, which triggers _______ to redirect blood flow to better-ventilated areas.
hypoxia, vasoconstriction
A right-to-left shunt involves cardiac output bypassing the _______, which normally accounts for about _______% of cardiac output.
alveoli
An increased shunt fraction results in _______.
hypoxemia
Left-to-right shunts are more _______ and do not cause hypoxemia.
common
Left-to-right shunts can be caused by conditions such as _______ or _______.
patent ductus arteriosus, traumatic injury
A left-to-right shunt leads to _______ PO2 in the right side of the heart.
elevated
Ventilation of non-perfused regions, as seen in pulmonary embolism, results in pulmonary capillary blood with _______ PO2.
high
In a right-to-left shunt, there is _______ gas exchange, resulting in pulmonary capillary blood with a PO2 similar to _______.
mixed venous PO2 (40 mm Hg)
Reduced or absent blood flow due to a shunt leads to _______ ventilation and _______ CO2 mixing.
low, no
The Bohr effect describes the phenomenon where, as PCO2 increases, the O2 content of blood _______.
decreases
The Haldane effect describes the phenomenon where, as PO2 increases, the CO2 content of blood _______.
decreases
Moving from a PCO2 of 44 mm Hg to 35 mm Hg allows for the same total O2 content to be carried at a _______ PO2.
lower
Therefore, reduced PCO2 enables the blood to carry a _______ total O2 content at the same PO2.
greater
It is important to note the difference in units between the axes in the O2-CO2 diagrams: _______ vs. _______.
mm Hg, mL/dL
If a patient’s PaCO2 is 50 mm Hg, the corresponding total CO2 content at a PO2 of 100 mm Hg would be approximately _______ ml/dL.
52
Pulmonary blood flow is influenced by _______ factors, including gravity and alveolar pressure, and _______ factors, such as hypoxic vasoconstriction.
passive, active
Dry air contains ____% nitrogen, ______% oxygen, _____% argon, and _____% carbon dioxide.
78.09%, 20.95%, 0.93%, 0.039%
Contraction & constriction occur in the airways due to __________ (muscarinic) receptors.
cholinergic
Relaxation & dilation occur in the airways due to __________ (beta2) receptors.
adrenergic
True or False: The diaphragm and intercostals are innervated by the somatic motor system.
True
