1. Why does the pulmonary circulatory circuit have low resistance? What conseque
ID: 3514040 • Letter: 1
Question
1. Why does the pulmonary circulatory circuit have low resistance? What consequence does this have for the risk of increasing MAP and of developing pulmonary edema?
a. Describe what partial pressure is and why it matters for the respiratory system. Why is it harder to breathe in high humidity? Why do we feel sick at high altitudes?
b. What is lung surfactant and why do we need it? You should understand how pressure varies in spheres of different sizes and the consequences for air movement and alveolar function. Secondly, address how surfactant fixes this problem.
c. What are the factors and conditions that induce bronchoconstriction vs bronchodilation? Your answer should include parasympathetic neurons, carbon dioxide, histamine and sympathetic epinephrine.
Explanation / Answer
1. The low resistance of pulmonary circulatory circuit arises due to absence of muscular arterioles unlike in systemic circulation, expansion of capillaries are high blood pressure condition, less distance that blood has to travel from heart to lungs, ability to carry large blood volume.
Pulmonary edema chances increase. Negative pressure pulmonary edema is observed when the main blood vessels are blocked and blood pressure increases within the lungs causing fluid formation.
a) In a mixture of gases, each gas exerts its own pressure which is a hypothetical quantity of pressure exerter by the gas when it occupies the entire volume. It is crucial in gas exchange. As air moves into the alveoli water vapor and. CO2 are added that reduces partial pressure of oxygen. Henry's law is applied to gas exchange as the partial pressures for oxygen and CO2 equilibrate across respiratory membrane.
It is difficult to breathe at high humidity because of more partial pressure exerted by water vapor which makes it difficult to attain equilibrium.
High altitudes cause low oxygen in lungs and decrease in partial pressure. Again more time is required to attain equilibrium. Hence we feel sick at high altitude.
b) Lung surfactant is a mixture of lipids and proteins which is secreted by epithelial type II cells into the alveolar space. Its main function is to reduce surface tension at the air/ liquid interface in the lungs and keeps them from collapsing when an individual exhales.
Surfactant reduces the pressure inside alveolar sacs alike and helps in respiration without pressure buildup and prevents it from collapsing.
c) Bronchoconstriction
Stimulation of colinergic nerves in parasympathetic neural system causes Bronchoconstriction as it is the primary neural pathway in control of airway. Bronchoconstriction is caused by low CO2 leading to inflammation, allergies and too much mucus in airways. Histamine exerts its effect by binding to histamine receptors. Activation of H1 receptors causes Bronchoconstriction. Parasympathetic stimulation through epinephrine causes Bronchoconstriction.
Bronchodilation
Stimulation is sympathetic neurons causes bronchodilation. Ncreased pressure of CO2 causes bronchodilation. Histamine H2 receptors mediate bronchodilation. Sympathetic stimulation by epinephrine is also a cause of bronchodilation.
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