Chap 23 Flashcards
What is Tidal Volume (TV)?
The amount of air inhaled or exhaled during a normal breath (~500 mL in adults)
Tidal Volume is a key measurement in assessing respiratory function.
What is Total Lung Capacity (TLC)?
The maximum amount of air the lungs can hold. TLC = Vital Capacity (VC) + Residual Volume (RV). Typical value: ~6,000 mL
TLC varies with age, sex, and body size.
What is Vital Capacity (VC)?
The total amount of air that can be exhaled after a maximal inhalation. VC = Tidal Volume (TV) + Inspiratory Reserve Volume (IRV) + Expiratory Reserve Volume (ERV). Typical value: ~4,800 mL
VC is an important measure for lung health.
What muscles are primarily involved in normal inhalation?
Diaphragm and external intercostals
The diaphragm is the most important muscle for breathing.
What happens during normal exhalation?
It is a passive process due to elastic recoil of lungs and relaxation of diaphragm and intercostals
No active muscle contraction is involved in normal exhalation.
What accessory muscles assist in forced inhalation?
Scalenes, sternocleidomastoid, and pectoralis minor
These muscles help expand the thorax during forceful breathing.
What muscles are involved in forced exhalation?
Internal intercostals and abdominal muscles (e.g., rectus abdominis, obliques)
These muscles actively push air out during forceful exhalation.
Define inhalation.
Active process where thoracic cavity volume increases, causing pressure to decrease, and air flows into the lungs
This process is explained by Boyle’s Law: Volume = (Pressure).
Define exhalation.
Normally passive, driven by elastic recoil of the lungs, which decreases thoracic cavity volume, increasing pressure and pushing air out
Exhalation typically requires no muscle contraction.
What is the role of surfactant in the lungs?
Reduces surface tension, preventing alveolar collapse during exhalation
Surfactant is produced by Type II alveolar cells.
What factors affect ventilation?
Surface tension of alveolar fluid, airway resistance, lung compliance
Each factor plays a crucial role in efficient breathing.
How does airway resistance affect ventilation?
Resistance increases with smaller airways (e.g., due to mucus or bronchoconstriction)
High airway resistance can impede airflow and reduce ventilation efficiency.
What does lung compliance refer to?
The lung’s ability to expand
Damaged elastic fibers (e.g., in emphysema) decrease compliance and increase the work of breathing.
What percentage of oxygen is bound to hemoglobin as oxyhemoglobin (HbOz)?
~98%
This indicates that the majority of oxygen transport in the blood relies on hemoglobin.
What is the primary form of carbon dioxide transport in the blood?
~70% as bicarbonate ions (HCO3~)
This is formed by the reaction of CO2 with water, catalyzed by carbonic anhydrase.
What is carbaminohemoglobin?
Hemoglobin bound to carbon dioxide
It is formed when CO2 binds to the globin portion of hemoglobin.
Define ventilation-perfusion coupling.
The matching of airflow (ventilation) and blood flow (perfusion) in the lungs
This process ensures that well-ventilated areas of the lung receive adequate blood flow.
What happens to hemoglobin’s affinity for oxygen in metabolically active tissues?
Decreased affinity
This occurs due to lower pH from increased CO2 production, facilitating oxygen delivery.
What effect does increased pH have on hemoglobin’s affinity for oxygen in the lungs?
Increased affinity
This occurs because CO2 is exhaled, leading to a lower concentration of H+ ions.
Where is the dorsal respiratory group (DRG) located?
In the medulla oblongata
It is part of the brainstem and plays a role in controlling breathing.
What is the primary function of the dorsal respiratory group (DRG)?
Sends rhythmic impulses to the diaphragm and external intercostal muscles
This initiates inhalation and primarily controls quiet breathing.
What is one effect of aging on lung compliance?
Decreased lung compliance
Aging reduces the elasticity of lung tissues, making breathing more difficult.
How does aging affect oxygen levels in the lungs?
Decreased oxygen levels
This is due to a decline in alveolar surface area and capillary density.
What happens to vital capacity as a person ages?
Decreased vital capacity
This is the maximum amount of air that can be exhaled after deep inhalation, reduced by aging-related factors.
What is the impact of aging on alveolar macrophage activity?
Decreased alveolar macrophage activity
This leads to an increased risk of infections and reduced ability to clear debris.
