Respiratory 1 Flashcards
(58 cards)
Why is haemoglobin essential for respiration in multicellular animals?
Because oxygen has very low solubility in fluids; haemoglobin binds and transports it efficiently.
What is the significance of the alveolar surface area?
It’s extremely large, allowing efficient gas exchange, and works in tandem with haemoglobin to supply oxygen to tissues.
What are the approximate percentages of gases in atmospheric air at sea level?
Oxygen ~21%, CO₂ negligible (~0.04%), Nitrogen ~78%.
What unit of pressure is preferred in the lecture and why?
Kilopascals (kPa), because 100 kPa = 1 atmosphere; more intuitive than mmHg and aligns with how gas volumes are measured in labs.
Why doesn’t breathing 100% oxygen help healthy individuals?
The respiratory system is not designed for it; pure oxygen can be toxic over time.
What happens to atmospheric pressure at high altitudes (e.g., Mount Everest)?
It drops significantly, making physical work difficult or impossible due to low oxygen availability.
What pressure is air in the alveoli typically at for oxygen and CO₂?
Oxygen: ~13.3 kPa (~13%), CO₂: ~5.3 kPa (~5%).
What kind of lung system do mammals have?
A “bag” system—air must be brought in and pushed out to refresh the alveolar gas reservoir.
Why doesn’t exhaled air contain 0% oxygen?
Because fresh inspired air (21% O₂) mixes with alveolar air (≈13% O₂), raising the O₂ concentration in exhaled air to ≈15%.
Why is gas exchange less efficient in humans compared to birds?
Humans have a tidal (in-and-out) system where air mixes in the same passages; birds have a unidirectional flow system, leading to more efficient oxygen exchange.
What is “dead space” in the respiratory system?
: It refers to airways (e.g., trachea, bronchi) where no gas exchange occurs—only respiratory bronchioles and alveoli allow exchange.
What causes the drop in oxygen concentration from the atmosphere (21%) to arterial blood (≈13%)?
Due to mixing of fresh and residual air, anatomical dead space, and diffusion limitations across the alveolar membrane.
What is VO₂ max?
The maximum rate of oxygen consumption per kg of body weight per minute, used as a measure of cardiovascular and respiratory fitness.
Why do elite athletes have high VO₂ max values?
They can intake and utilize more oxygen due to superior cardiovascular and muscular efficiency.
How is oxygen used at the cellular level?
It is the final electron acceptor in the electron transport chain, enabling ATP production via oxidative phosphorylation.
What is ATP and why is it important?
ATP (adenosine triphosphate) powers cellular processes, especially muscle contraction, by causing conformational changes in proteins like myosin and actin.
What makes the trachea and bronchi structurally rigid?
Why is mucus important in the respiratory tract?
How is air drawn into the lungs during normal breathing?
The diaphragm contracts, expanding the thoracic cavity, decreasing pressure inside the lungs, causing air to rush in.
What is the pleura and its role?
A double membrane surrounding the lungs; it creates a slight pressure difference aiding lung inflation and preventing collapse.
Why is breathing out (exhalation) active during exercise?
Muscles (e.g., abdominal, intercostal) contract to forcefully expel air, requiring energy.
What organism is responsible for producing atmospheric oxygen?
Cyanobacteria (formerly called blue-green algae) through photosynthesis.
Why does Earth’s oxygen allow multicellular life to exist?
High oxygen levels enable aerobic respiration, which yields much more ATP than anaerobic processes.
What does the vertical axis represent on a lung volume diagram?
Lung volume, ranging typically from 0 mL to around 6000 mL.
What is tidal volume and its typical value?
Tidal volume is the amount of air moved in and out during normal breathing, about 500 mL.
