if hemoglobin in RBCs are 91% saturated in the lungs (PO2 of 100). What is the of o2 saturation in the hemoglobin at a PO2 of 30?At a PO2 of 30, what percent of the oxygen was released into the tissue?
53%, 38%
A person with ketoacidosis may hyperventilate. Explain why this occurs and explain why this hyperventilation can be stopped by an intravenous fluid containing bicarbonate
Low pH triggers fast breathing to dump CO₂. Bicarbonate neutralizes H+, so breathing slows.
Describe how temperature, CO₂, and pH each affect hemoglobin’s affinity for oxygen.
↑CO₂ & ↓pH (Bohr effect) → right shift → ↓affinity → ↑O₂ release • ↑Temperature → right shift → ↑O₂ release • Opposite changes shift curve left → ↑affinity → ↓O
Describe the pressure changes during normal inhalation and why air enters the lungs.
Diaphragm & external intercostals contract, volume increases, intrapleural pressure becomes more(-),alveolar pressure drops below atmospheric, air pushed in
Define restrictive pulmonary disease and give two examples.
Restrictive disease limits lung expansion difficulty inhaling & reduced lung volumes. Pulmonary fibrosis, scoliosis/kyphosis, ALS, myasthenia gravis, RDS
if hemoglobin in RBCs are 98% saturated in the lungs (PO2 of 100). What is the of o2 saturation in the hemoglobin at a PO2 of 40?At a PO2 of 40, what percent of the oxygen was released into the tissue?
72%, 26%
Explain the difference between external respiration and internal (cellular) respiration.
External respiration: Gas exchange between alveoli and blood. • Internal/cellular respiration: Mitochondria use O₂ and produce CO₂ during metabolism.
During intense exercise, explain how CO₂, pH, and temperature changes enhance O₂ delivery in tissues.
↑CO₂, ↑heat, ↓pH → right shift more O₂ released. (• ↑CO₂ → forms carbonic acid → ↓pH
• ↑Lactic acid → ↓pH
• ↑Temperature)
Describe the role of surfactant and what happens when it is absent.
Surfactant reduces surface tension in alveoli, keeping them open and easy to inflate. Without it alveoli collapse- premies, respiratory distress syndrome
Explain how CO₂ levels influence blood pH and ventilation rate.
CO₂ + H₂O → H₂CO₃ → H⁺ + HCO₃⁻, Peripheral sensors detect H⁺; central sensors detect CO₂ (via pH).
Explain the difference between Type I and Type II alveolar cells and why each is essential.
Type I cells: Simple squamous, main site of gas exchange. Type II cells: Produce surfactant, lowering surface tension and preventing collapse
A COPD patient becomes confused after receiving high-flow oxygen. Explain why this happens using chemoreceptor physiology.
COPD patients retain CO₂, so CO₂/pH sensors weaken. They rely on low O₂ to breathe. Giving too much O₂ removes this drive → breathing drops → CO₂ rises → acidos
Explain why intrapleural pressure must remain negative and what happens if it becomes positive.
Negative intrapleural pressure keeps lungs adhered to the thoracic wall. If it becomes zero or positive, lung collapses because recoil is unopposed
Describe fetal hemoglobin and explain how its structure creates higher oxygen affinity.
Fetal Hb cannot bind 2,3-BPG, so it holds oxygen more tightly → curve shifts left. This enables fetal blood to “pull” oxygen from maternal blood.
What structure marks the division between the upper and lower respiratory system?
The larynx is the beginning of the lower respiratory system
Define obstructive pulmonary disease and give two examples.
Obstructive disease involves narrowed or blocked airways- difficulty exhaling; airflow is slowed. Asthma, emphysema, chronic bronchitis, COPD.
Describe where central and peripheral chemoreceptors are located and what each detects.
Central chemoreceptors: Medulla; sense ↑CO₂ and ↓pH in CSF. Peripheral chemoreceptors: Carotid & aortic bodies; sense H⁺ from CO₂ and low O₂ levels.
Define tidal volume, inspiratory reserve volume, and residual volume.
Tidal Volume: Air per quiet breath, Inspiratory Reserve Volume: Max inhaled after a normal inhale, Residual Volume: Air left after maximal exhalation
What causes a right shift of the oxygen–hemoglobin curve?
↑CO₂, ↓pH, ↑temperature, ↑2,3-BPG → more O₂ released to tissues.
What happens to intrapleural pressure during inhalation?
It becomes more negative, helping pull the lungs outward.