resp 2 Flashcards
Explain the functional difference between the conducting and respiratory zones in the mammalian respiratory system.
The conducting zone moves air and is reinforced with cartilage and smooth muscle, while the respiratory zone facilitates gas exchange and lacks significant structural reinforcement.
Why is the respiratory zone structurally different from the conducting zone?
It lacks cartilage and smooth muscle to allow thin membranes and close proximity between air and blood for efficient gas exchange.
How does Dalton’s Law apply to respiratory physiology?
It explains that the total atmospheric pressure is the sum of the partial pressures of individual gases, which determines how gases like O2 and CO2 diffuse into blood.
What physiological principle explains why expanding the chest cavity during breathing causes air to flow in?
Boyle’s Law: as thoracic volume increases, intrapulmonary pressure drops below atmospheric pressure, causing air to flow into the lungs.
How does Henry’s Law relate to oxygen absorption into the bloodstream?
It shows that gas solubility and partial pressure determine how much O2 dissolves in blood plasma.
What pressure differences drive air into the lungs during inhalation?
Air enters when intra-alveolar pressure becomes lower than atmospheric pressure due to expansion of the thoracic cavity.
Why is intrapleural pressure always negative, and why is that important?
It prevents lung collapse by keeping the lungs expanded and connected to thoracic wall movement.
What is the function of the pleural fluid in the breathing process?
It reduces friction and allows smooth sliding of lung surfaces against the chest wall during breathing.
Describe the role of the medulla oblongata in ventilation control.
It contains central pattern generators that initiate signals to respiratory muscles, regulating the breathing rhythm.
Why is inhalation considered an active process while exhalation can be passive?
Inhalation requires muscle contraction (diaphragm and intercostals), while passive exhalation relies on elastic recoil.
Under what circumstances does exhalation become an active process?
During exercise or forced breathing, when internal intercostals and abdominal muscles contract to push air out.
What do ventilation and perfusion mean in terms of respiratory function?
Ventilation is the movement of air into lungs, and perfusion is the flow of blood through pulmonary capillaries for gas exchange.
Which cellular components of the alveoli support gas exchange and immune defense?
Type I epithelial cells allow gas diffusion, Type II cells secrete surfactant, and macrophages provide immune defense.
Why is surfactant critical for normal breathing?
It reduces surface tension in alveoli, preventing collapse and making it easier for lungs to expand.
Apply Fick’s law to explain how alveolar structure supports efficient gas exchange.
Alveoli maximize surface area (A), minimize membrane thickness (X), and maintain pressure gradients (ΔP) to enhance diffusion rate (J).
What determines the rate of gas diffusion across respiratory membranes?
Surface area, membrane thickness, and the partial pressure gradient of the gas, per Fick’s law.
Why does the partial pressure of oxygen decrease along its transport pathway?
Oxygen is consumed at each step (alveoli → blood → tissues → mitochondria), reducing its partial pressure progressively.
What is the physiological significance of maintaining a high enough PO2 at the mitochondria?
It ensures that cells can produce ATP efficiently through aerobic respiration.
Why is the solubility of oxygen in blood plasma alone insufficient for human needs?
Because only 1.5% of oxygen dissolves in plasma; hemoglobin is needed to carry the rest efficiently.
Describe how hemoglobin’s structure supports its oxygen-carrying function.
Hemoglobin has four heme groups, each binding an O2 molecule, allowing one Hb to carry four oxygen molecules.
What is cooperative binding in hemoglobin and why is it important?
It means binding of one O2 increases the affinity for others; this allows efficient oxygen loading in lungs and unloading in tissues.
Why is allosteric modulation important in hemoglobin function?
It allows hemoglobin to adjust its affinity for O2 based on the local environment (pH, CO2), optimizing gas transport.
How do changing CO2 levels affect hemoglobin’s ability to carry oxygen?
High CO2 lowers pH, reducing hemoglobin’s affinity for O2 (Bohr effect), which promotes oxygen release in tissues.
What factors influence oxygen unloading from hemoglobin in the tissues?
Low PO2, high CO2, high temperature, and low pH all favor oxygen release from hemoglobin.
