22.3
La capacidad pulmonar
El aire en los pulmones se mide en volúmenes y capacidades. Las medidas del volumen pulmonar reflejan la cantidad de aire que se inhala, se libera o q…
- [Instructor] El tamaño de los pulmones puede variar
dependiendo de la experiencia y tamaño corporal.
La cantidad de aire que puede entrar o salir de los pulmones
se mide como cuatro volúmenes,
funciones únicas, como inhalación,
y cuatro capacidades,
cantidades comparativas de múltiples volúmenes.
La cantidad de aire normalmente inhalada y exhalada
se llama volumen corriente,
mientras que al aire que puede ser respirado o exhalado
tras inhalación o exhalación
se le llama volúmenes de reserva inspiratorios
y expiratorios.
El cuarto volumen es la cantidad de aire
que permanece en los pulmones
tras el volumen de reserva expiratorio,
conocido como volumen de reserva residual,
la pequeña cantidad de aire que no deja los pulmones
manteniéndolos inflados.
Esta cantidad combinada con los otros volúmenes
es la capacidad pulmonar total,
la cantidad entera de aire que los pulmones pueden sostener,
aproximadamente seis litros.
Dentro de un único ciclo respiratorio,
la cantidad máxima de aire
que puede moverse dentro o fuera es la capacidad vital,
esencialmente una suma de los volúmenes corriente
y ambos volúmenes de reserva.
Las capacidades restantes son la capacidad inspiratoria,
qué tanto puede ser inhalado tras exhalación normal
y la capacidad residual funcional,
qué tanto aire permanece tras exhalar.
Ultimadamente estas mediciones
se usan para diagnosticar enfermedades pulmonares,
como asthma donde más aire permanece en los pulmones
tomando más tiempo para la exhalación
o fibrosis pulmonar donde un volumen rápidamente se vacía
lo que resulta en la falta de aliento.
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Q1: What is the difference between lung volumes and lung capacities?
Lung volumes measure air during single respiratory functions like inhalation or exhalation, while lung capacities represent sums of two or more volume measures. There are four lung volumes: tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume. Four capacities combine these volumes to show total air movement potential during breathing cycles.
Q2: How much air does tidal volume represent in normal breathing?
Tidal volume is the amount of air normally inhaled and exhaled during a regular breath without forced effort. This is the baseline air movement during quiet, resting breathing. It represents the air exchanged during each normal respiratory cycle before any reserve volumes are engaged.
Q3: What is residual volume and why does it matter?
Residual volume is the small amount of air remaining in the lungs after forced exhalation, keeping the lungs inflated and preventing collapse. This air cannot be voluntarily expelled. Combined with other volumes, residual volume contributes to total lung capacity, approximately six liters in adult males and 4.2 liters in adult females.
Q4: What does vital capacity measure during breathing?
Vital capacity is the maximum volume of air that can be exhaled after maximal inhalation, representing the sum of tidal volume, inspiratory reserve volume, and expiratory reserve volume. It measures the maximal amount of air that can be moved in or out during a single respiratory cycle, excluding residual volume.
Q5: How do inspiratory and expiratory reserve volumes differ?
Inspiratory reserve volume is the additional air that can be inhaled after normal inhalation, while expiratory reserve volume is the extra air that can be exhaled after normal exhalation. Together with tidal volume, these reserves determine how much extra breathing capacity exists beyond routine respiration and are essential for activities requiring increased oxygen intake.
Q6: How are lung capacity measurements used to diagnose respiratory diseases?
Lung capacity measurements help identify diseases by revealing abnormal air retention or rapid emptying patterns. In asthma, more air remains in the lungs, prolonging exhalation. In pulmonary fibrosis, lung volume empties rapidly, causing shortness of breath. These measurements provide objective data for diagnosing and monitoring respiratory conditions.
Q7: What is functional residual capacity and how is it calculated?
Functional residual capacity is the volume of air remaining in the lungs after normal exhalation, calculated as the sum of expiratory reserve volume and residual volume. This measurement shows how much air stays in the lungs during quiet breathing and is important for understanding gas exchange and transport during the respiratory cycle.