ch. 22 & 23 unit objectives

Front: What is the diaphragm's role in respiration?

Back: Prime mover of respiration. Contraction flattens diaphragm, enlarging thoracic cavity, pulling air into lungs. Relaxation allows diaphragm to bulge upward, compressing lungs and expelling air.

Front: What are the roles of the external intercostals in respiration?

Back: Stiffen thoracic cage, prevent inward collapse during inspiration, contribute about 1/3 of air inhaled.

Front: How do the scalenes assist in breathing?

Back: Fix or elevate ribs 1 and 2, assisting in inspiration.

Front: Which accessory muscles are involved in forced respiration?

Back: Erector spinae, pectoralis major and minor, serratus anterior increase thoracic volume during forced inhalation.

Front: What role do abdominal muscles play in forced expiration?

Back: Increase abdominal pressure pushing viscera against diaphragm, aiding in forced expiration.

Front: What are the three brainstem centers controlling breathing?

Back:

• Ventral respiratory group (VRG): Generates respiratory rhythm (~12 breaths/min).

• Dorsal respiratory group (DRG): Modifies rate and depth of breathing.

• Pontine respiratory group (PRG): Adapts breathing to activities like sleep, exercise, vocalization.

Front: How does Boyle's Law relate to respiration?

Back: At constant temperature, gas pressure is inversely proportional to volume. Lung volume increases -> pressure drops -> air flows in. Lung volume decreases -> pressure rises -> air flows out.

Front: What happens during inhalation?

Back: Thoracic cavity expands -> lung volume increases -> intrapulmonary pressure drops below atmospheric pressure -> air flows in.

Front: What happens during exhalation?

Back: Thoracic cavity contracts -> lung volume decreases -> intrapulmonary pressure rises above atmospheric pressure -> air flows out.

Front: What causes bronchodilation?

Back: Sympathetic stimulation and epinephrine -> increased bronchiole diameter -> decreased resistance -> increased airflow.

Front: What causes bronchoconstriction?

Back: Parasympathetic nerves, histamine, cold air, irritants -> decreased bronchiole diameter -> increased resistance -> decreased airflow.

Front: What is pulmonary compliance?

Back: Ease of lung expansion; influenced by elasticity of lung tissue and surface tension in alveoli.

Front: How does surface tension affect alveolar ventilation?

Back: Surfactant reduces surface tension in alveoli, preventing collapse and maintaining airflow.

Front: What is anatomical dead space?

Back: Air in the conducting zone (nose, pharynx, larynx, trachea, bronchi) that doesn't participate in gas exchange (~150 mL).

Front: How is alveolar ventilation rate (AVR) calculated?

Back: AVR = (Tidal volume - Dead space) × Respiratory rate

Front: What is tidal volume (TV)?

Back: Volume of air inhaled and exhaled in one cycle of breathing (~500 mL).

Front: What is inspiratory reserve volume (IRV)?

Back: Additional air inhaled with maximum effort (~3,000 mL).

Front: What is expiratory reserve volume (ERV)?

Back: Additional air exhaled with maximum effort (~1,200 mL).

Front: What is residual volume (RV)?

Back: Air remaining in lungs after maximum expiration (~1,300 mL).

Front: How is vital capacity (VC) calculated?

Back: Max air exhaled after max inhalation: VC = TV + IRV + ERV (~4,700 mL).

Front: What is inspiratory capacity (IC)?

Back: Max air inhaled after tidal expiration: IC = TV + IRV (~3,500 mL).

Front: How is functional residual capacity (FRC) calculated?

Back: Air remaining in lungs after tidal expiration: FRC = RV + ERV (~2,500 mL).

Front: How is total lung capacity (TLC) calculated?

Back: Max air lungs can hold: TLC = RV + VC (~6,000 mL).