Respiration 3 Flashcards
a law that states in a mixture of gasses, each gas will move independantly”
a. Ficks law
b. Daltons law
Daltons law
how is P(atm) determined?
determined by summing up all partial pressures of elements in the air (nitrogen, ocygen, h20, and CO2)
what does Fick’s law tell us?
the rate of transfer of a gas through a membrane is porportional to the area, diffusion constant, and the differences of partial pressure between the two sides
the rate of transfer of a gas is inversely porportional to thickness
Carbon dioxide (CO₂) diffuses more rapidly than oxygen (O₂) across the alveolar membrane. What primarily explains this difference?
A) CO₂ has a higher solubility in blood than O₂, allowing it to diffuse more efficiently despite similar molecular weights.
B) CO₂ has a higher diffusion constant than O₂, making its transport across the membrane faster.
C) CO₂ has a greater ability to dissolve in plasma compared to O₂, increasing its diffusion rate.
D) CO₂ has a higher dissolving capacity in bodily fluids than O₂, enhancing its transfer rate.
Answer:
A) CO₂ has a higher solubility in blood than O₂, allowing it to diffuse more efficiently despite similar molecular weights.
why is Po2 in the alveoli less than Po2 in the air? state the 3 reasons:
- humidity and warmth in respiratory system ↓Po2
- loss of oxygen by diffusion ↓Po2
- mixing air with residual volume ↓Po2
Which of the following are the key determinants of alveolar partial pressure of oxygen (PAO₂) and carbon dioxide (PACO₂)?
A) Inspired PO₂, alveolar ventilation, metabolic rate, and perfusion.
B) Atmospheric pressure, respiratory rate, lung compliance, and tidal volume.
C) Oxygen solubility, airway resistance, pulmonary surfactant, and hemoglobin saturation.
D) Diffusion capacity, bronchial circulation, lung volume, and oxygen consumption.
Inspired PO₂ – The amount of oxygen in the air we breathe.
Alveolar ventilation (VA) – Determines how much fresh air reaches the alveoli.
Va=(Vt-Vdead space)xbpm
Metabolic rate – Higher oxygen consumption and CO₂ production shift alveolar gas levels.
Perfusion (pulmonary blood flow) – Affects gas exchange efficiency and equilibrium with blood.
(a)
what occurs for the ALVEOLAR partial pressures of oxygen and Co2 during hypoventilation and hyperventilation?
hypoventilation (shallow breath):
PO2<PCO2
hyperventilating (deep breath)
PO2>PCO2
amount of blood that passes through the pumonaty capillary system in the lung
a. lung perfusion
b. systematic circulation
c. pulmonary circulation
lung perfusion
a HIGH PRESSURE SYSTEM, overcome high resistance systems, and necessary for delivering blood to tissue
a. lung perfusion
b. systematic circulation
c. pulmonary circulation
systematic circulation
LOW PRESSURE SYSTEM, necessary for delivery blood to only lungsm and high pressures are risky (lung edema)
a. lung perfusion
b. systematic circulation
c. pulmonary circulation
pulmonary circulation
How does hypoxic pulmonary vasoconstriction (HPV) help optimize ventilation-perfusion (V/Q) matching in the lungs?
A) When alveolar PO₂ is low, pulmonary arterioles constrict, redirecting blood flow to alveoli with higher oxygen levels to improve gas exchange efficiency.
B) When alveolar PO₂ is low, pulmonary arterioles dilate, allowing more blood flow to compensate for reduced oxygen availability.
C) When alveolar PCO₂ is high, pulmonary vasoconstriction increases to limit CO₂ exchange and preserve acid-base balance.
D) When alveolar ventilation decreases, pulmonary arteries increase blood flow to restore normal gas exchange rates.
When alveolar PO₂ is low, pulmonary arterioles constrict, redirecting blood flow to alveoli with higher oxygen levels to improve gas exchange efficiency.
what is a major factor affecting alveolar levels of O2 and CO2?
the vasoconstriction/perfusion system
Under which condition does bronchoconstriction occur, and what is its physiological purpose?
A) When alveolar PO₂ is low, bronchoconstriction reduces airflow to poorly oxygenated alveoli to optimize ventilation-perfusion (V/Q) matching.
B) When alveolar PCO₂ is low, bronchoconstriction decreases ventilation to underperfused alveoli, maintaining proper V/Q balance.
C) When alveolar PO₂ is high, bronchoconstriction limits ventilation to prevent excessive oxygen intake.
D) When metabolic demand increases, bronchoconstriction ensures better oxygen distribution by restricting airflow.
When alveolar PCO₂ is low, bronchoconstriction decreases ventilation to underperfused alveoli, maintaining proper V/Q balance.
what happens to the partial pressure of oxygen and CO2 INITIALLY when ventilated alveoli LACK perfusion
Po2 ↑ and Pco2↓
increasing V/Q ratio
A lack of perfusion leads to bronchoconstriction
what happens to the partial pressure of oxygen and carbon dioxide INITIALLY when perfused alveoli are not ventilated?
Po2↓ and Pco2 ↑
decreasing V/Q ratio
Decreased ventilation leads to vasoconstriction
during CO2 transport, what chemical is mostly present?
a. carbonic acid
b. carbaminohemoglobin
c. oxygen
d. bicarbonate
bicarbonate is the most present
second is carbaminohemoglobin (carbon dioxide binded to hemoglobin)
When Does Pressure Go Up or Down?
Which condition would most likely result in an increase in alveolar PO₂ and a decrease in alveolar PCO₂?
A) Hypoventilation with a reduced respiratory rate.
B) Increased metabolic rate due to intense physical activity.
C) Hyperventilation with rapid, deep breathing.
D) Decreased alveolar ventilation due to airway obstruction.
Hyperventilation leads to increased oxygen intake and faster expulsion of CO₂, increasing PO₂ and decreasing PCO₂.
C
Which of the following best defines partial pressure in the context of respiratory physiology?
A) The total pressure exerted by all gases in a mixture, directly proportional to their molecular weights.
B) The pressure exerted by an individual gas in a mixture, independent of other gases present.
C) The cumulative pressure of gases in alveoli after diffusion has reached equilibrium.
D) The sum of atmospheric and alveolar gas pressures affecting ventilation rates.
: Partial pressure is the pressure exerted by a single gas within a mixture, independent of other gases, as explained by Dalton’s Law.
B
According to Fick’s Law, which scenario would result in the greatest increase in the rate of gas diffusion across the alveolar membrane?
A) Decreasing the alveolar surface area while increasing the membrane thickness.
B) Increasing the partial pressure gradient while maintaining the same membrane thickness.
C) Reducing the diffusion constant for the gas to improve selective permeability.
D) Equalizing the partial pressures on both sides of the membrane to enhance equilibrium.
Fick’s Law states that the rate of diffusion is directly proportional to the surface area, diffusion constant, and partial pressure gradient, and inversely proportional to membrane thickness.
B
What are the three pathways for CO2 in intersitiual fluid?
- Remain dissolved in plasma
- Enter RBC as dissolved CO2
- Reacts with water to make carbonic acid, then bicarbonate; regulate pH in th blood
Which of the following best explains why CO₂ diffuses from the blood into the alveoli during gas exchange in the lungs?
A) CO₂ moves actively across the alveolar membrane using ATP-dependent transporters.
B) The concentration of oxygen in the alveoli pulls CO₂ out of the blood through competitive binding.
C) CO₂ diffuses down its partial pressure gradient, from higher PCO₂ in the blood to lower PCO₂ in the alveoli.
D) The alveolar walls contain enzymes that chemically force CO₂ out of the blood.
CO₂ moves due to the concentration gradient, specifically a partial pressure gradient.
Which of the following best explains why most H⁺ ions are not freely dissolved in the blood and the role of hemoglobin (Hb) in buffering?
A) H⁺ ions are too large to remain dissolved in plasma and require binding to hemoglobin for transport.
B) Free H⁺ ions would drastically alter blood pH, so hemoglobin binds to H⁺ to help maintain acid-base balance.
C) H⁺ ions are hydrophobic and cannot dissolve in the aqueous environment of blood plasma.
D) Hemoglobin binds H⁺ ions to prevent them from interfering with oxygen binding at the heme group.
Free H⁺ ions in the blood would significantly disrupt acid-base homeostasis by rapidly lowering pH. Hemoglobin acts as a buffer by binding to these H⁺ ions, particularly at its histidine residues, thereby reducing fluctuations in blood pH and maintaining physiological balance without interfering with oxygen transport.
B
Hypoventilation that leads to increased PCO2 and Increased proton concentration (H+)
A. Respiratory acidosis
B. Respiratory acidosis
C. Metabolic acidosis
D. Metabolic alkalosis
Respiratory acidosis
Hyperventilation occurs, where the partial pressure of CO2 decreases and the H+ concentration decreases
A. Respiratory acidosis
B. Respiratory alkalosis
C. Metabolic acidosis
D. Metabolic alkalosis
Respiratory alkalosis
