Respiratory System Functions and Volumes

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Questions and Answers

What is the primary role of the respiratory system?

Remove CO2 from and deliver O2 to the cells.

What happens when the diaphragm contracts?

The thoracic cavity gets larger, pressure decreases, and atmospheric gas enters the lungs.

What happens when the diaphragm relaxes?

Thoracic cavity gets smaller, pressure increases, and air is forced out of the lungs.

According to the lab book, what muscle contracts when the diaphragm contracts while the person is running?

The external intercostals. Signup and view all the answers

According to the lab book, what muscles contract when the diaphragm relaxes while the person is running?

The internal intercostals. Signup and view all the answers

What is tidal volume the product of?

Frequency of breathing * V of each breath. Signup and view all the answers

What is partial pressure?

The proportion of pressure that a single gas exerts within a mixture. Signup and view all the answers

What is the normal volume of tidal volume in people?

500 mL Signup and view all the answers

What is inspiratory reserve volume?

The maximum volume of air you can breathe in after a normal inhalation. Signup and view all the answers

What is the normal volume of inspiratory reserve volume?

3100 mL Signup and view all the answers

What is expiratory reserve volume?

The maximum volume of air you can breathe out after a normal exhalation. Signup and view all the answers

What is the normal volume of expiratory reserve volume?

1200 mL Signup and view all the answers

What is vital capacity?

ERV + TV + IRV Signup and view all the answers

What is the normal volume of vital capacity?

4800 mL Signup and view all the answers

What prevents us from breathing out all the air in our lungs?

The histological structure of the respiratory tree. Signup and view all the answers

After a complete exhalation, what remains?

Residual volume. Signup and view all the answers

What is the normal volume of residual volume?

1200 mL Signup and view all the answers

What is the volume of total lung capacity?

6000 mL Signup and view all the answers

What are the components of total lung capacity?

ERV + TV + IRV + RV Signup and view all the answers

What can't a spirometer measure?

Residual volume. Signup and view all the answers

What is forced vital capacity?

The amount of air that can be expelled completely and as rapidly as possible after taking in the deepest breath possible. Signup and view all the answers

What is forced expiratory volume (FEV1)?

The % of vital capacity that is exhaled during a 1 second period of the FVC test. Signup and view all the answers

What is the normal range of FEV1?

75%-85% Signup and view all the answers

What is surfactant?

A lipid material excreted into the alveolar fluid that decreases the surface tension of water in the fluid that lines the alveoli. Signup and view all the answers

What would happen without surfactant?

The surface tension of water would cause alveoli to collapse after each breath. Signup and view all the answers

What would happen to the pressure in the lungs if they were punctured?

The intrathoracic pressure would equilibrate with atmospheric pressure, thus there would be no gradient for air to travel into and out of the lungs. Signup and view all the answers

How is the adequacy of alveolar ventilation measured?

In terms of partial pressure of CO2. Signup and view all the answers

What is perfusion?

Pulmonary blood flow. Signup and view all the answers

What is perfusion matched to?

Ventilation. Signup and view all the answers

During rapid breathing, what happens to alveolar ventilation?

Alveolar ventilation becomes excessive for tissue needs, resulting in a decrease in the ratio of CO2 production to alveolar ventilation. Signup and view all the answers

During rebreathing, what happens to PCO2?

PCO2 is elevated in the alveolus and consequently in the blood. Signup and view all the answers

In breath holding, what happens to gas exchange?

There is no ventilation and no gas exchange between the alveolus and the blood. Signup and view all the answers

With emphysema, what happens to the lung tissue?

There is a significant loss of elastic recoil in the lung tissue. Signup and view all the answers

Why is there a loss of elastic recoil in the lungs during emphysema?

The disease destroys the walls of the alveoli. Signup and view all the answers

How is airway resistance increased in emphysema?

Lung tissue becomes flimsy and exerts less mechanical tethering on the surrounding airways, thus the lung becomes overly compliant and expands easily. Signup and view all the answers

Why is there a great effort to exhale with emphysema?

The lungs can no longer passively recoil and deflate. Signup and view all the answers

Study Notes

Primary Role of the Respiratory System

Main function: Remove carbon dioxide (CO2) and deliver oxygen (O2) to cells.

Diaphragm Function

Contraction of diaphragm enlarges thoracic cavity, reducing pressure and allowing atmospheric air to enter lungs.
Relaxation of diaphragm decreases size of thoracic cavity, increasing pressure and forcing air out of lungs.

Muscle Involvement During Exercise

External intercostals contract alongside diaphragm during running.
Internal intercostals contract when diaphragm relaxes during exertion.

Lung Volumes

Tidal Volume (TV): Average volume in people is 500 mL; represents the amount of air inhaled or exhaled in a normal breath.
Inspiratory Reserve Volume (IRV): Maximum volume of air inhaled after a normal inhalation; normal value is 3100 mL.
Expiratory Reserve Volume (ERV): Maximum volume of air exhaled after a normal exhalation; normal value is 1200 mL.
Vital Capacity (VC): Total air capacity for breathing; calculated as ERV + TV + IRV; normal value is 4800 mL.
Residual Volume (RV): Volume of air remaining in lungs after complete exhalation; normal value is 1200 mL.
Total Lung Capacity (TLC): Total air capacity of the lungs; calculated as ERV + TV + IRV + RV; normal value is 6000 mL.

Spirometry

Spirometer cannot measure residual volume (RV).
Forced Vital Capacity (FVC): Total amount of air expelled rapidly after deep inhalation.
Forced Expiratory Volume (FEV1): Percentage of vital capacity exhaled in one second during FVC test; normal range is 75%-85%.

Surfactant

Lipid material secreted in alveolar fluid; reduces water surface tension in alveoli.
Absence of surfactant leads to potential alveolar collapse due to high surface tension.

Pressure and Ventilation

Punctured lungs equalize intrathoracic pressure with atmospheric pressure, hindering airflow.
Adequacy of alveolar ventilation evaluated through the partial pressure of CO2.
Perfusion refers to pulmonary blood flow, which is matched to ventilation.

Breathing Patterns

Rapid breathing can cause excessive alveolar ventilation relative to tissue needs, lowering CO2 production ratio.
Rebreathing increases PCO2 levels in alveoli and blood.
Breath holding stops ventilation and gas exchange between alveolus and blood.

Emphysema Effects

Significant loss of elastic recoil in lung tissue due to disease.
Alveolar wall destruction leads to reduced mechanical support for airways, increasing airway resistance.
Difficulty exhaling as lungs lose passive recoil and cannot deflate easily.

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Description

Explore the essential roles of the respiratory system, including the uptake of oxygen and removal of carbon dioxide. Understand the mechanics of the diaphragm, the involvement of intercostal muscles during exercise, and learn about various lung volumes such as tidal and vital capacity.