Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Assessment of Ventilation II: Respiratory Depth and Rhythm

Assessment of Ventilation II: Respiratory Depth and Rhythm

Respiratory Depth
Respiratory depth measures the volume of air inhaled or exhaled during a breath. It can vary from shallow to deep and typically remains consistent when a person is at rest or asleep. Occasionally, individuals will automatically inhale deeply, known as sighing, which inflates the lungs with more air than normal breathing.
To assess respiratory depth, observe the degree of chest excursion or movement:

Factors Affecting Pulmonary Ventilation

Factors Affecting Pulmonary Ventilation

Besides the pressure difference between the external environment and the lungs, the airflow rate and ease of pulmonary ventilation are also influenced by three other factors: surface tension of the fluid in the alveoli, compliance of the lungs, and airway resistance.
Alveolar Surface Tension
The alveolar fluid lines the luminal surface of the alveoli and exerts a force called surface tension. This force is caused by the polar water molecules in the liquid being more strongly attracted to each...

Behavior of Gas Molecules: Molecular Diffusion, Mean Free Path, and Effusion

Behavior of Gas Molecules: Molecular Diffusion, Mean Free Path, and Effusion

Although gaseous molecules travel at tremendous speeds (hundreds of meters per second), they collide with other gaseous molecules and travel in many different directions before reaching the desired target. At room temperature, a gaseous molecule will experience billions of collisions per second. The mean free path is the average distance a molecule travels between collisions. The mean free path increases with decreasing pressure; in general, the mean free path for a gaseous molecule will be...

Respiratory System Abnormal Finding II: Palpation and Auscultation

Respiratory System Abnormal Finding II: Palpation and Auscultation

In assessing respiratory abnormalities, palpation and auscultation are critical tools for detecting and interpreting various pathophysiological changes. These techniques provide insight into underlying disorders by evaluating tactile sensations and sounds produced by the respiratory system.
Palpation Findings
During a respiratory assessment, palpation can reveal several vital abnormalities:

External and Internal Respiration

External and Internal Respiration

External respiration occurs in the lungs, and it is the first step in the journey of oxygen inside the body. When we inhale, oxygen enters our lungs and diffuses across the thin alveolar membrane. The alveoli are tiny, air-filled sacs that provide a vast surface area for gas exchange. Oxygen in the alveoli has a higher partial pressure (105 mmHg) than in the adjacent pulmonary capillaries (40 mmHg), establishing a pressure gradient. As a result, oxygen molecules move from the alveoli into the...

Pulmonary Cycle: Exhalation

Pulmonary Cycle: Exhalation

In terms of human respiration, the act of expelling air, known as exhalation (or expiration), operates on the principle of pressure gradients. During expiration, the pressure within the lungs exceeds that of the surrounding atmosphere. Under normal conditions, quiet breathing involves passive exhalation and is free of muscular contractions. This is because the exhalation process is driven by the natural elastic recoil of the lungs and chest wall, both of which have an inherent tendency to...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

The Air Density Equation and the Transfer of the Mass Unit.

Journal of research of the National Bureau of Standards (1977)·2021

Same author

In-Tank Measurement of Solution Density.

Journal of research of the National Bureau of Standards (1977)·2021

Same author

Identification of New Mono/Dihydroxynaphthoquinone as Lead Agents That Inhibit the Growth of Refractive and Triple-Negative Breast Cancer Cell Lines.

ACS omega·2019

Same author

Direct coupling of the HER4 intracellular domain (4ICD) and STAT5A signaling is required to induce mammary epithelial cell differentiation.

Biochemistry and biophysics reports·2017

Same author

Ablating ErbB4 in PV neurons attenuates synaptic and cognitive deficits in an animal model of Alzheimer's disease.

Neurobiology of disease·2017

Same author

ITS-90 Density of Water Formulation for Volumetric Standards Calibration.

Journal of research of the National Institute of Standards and Technology·2017

Search research articles

Related Experiment Video

Updated: Oct 19, 2025

Rapid Viscoelastic Characterization of Airway Mucus Using a Benchtop Rheometer

Rapid Viscoelastic Characterization of Airway Mucus Using a Benchtop Rheometer

Published on: April 21, 2022

The Refractivity of Air.

Frank E Jones¹

¹National Bureau of Standards, Washington, DC 20234.

Journal of Research of the National Bureau of Standards (1977)

|September 27, 2021

Summary

This summary is machine-generated.

A new simplified equation accurately calculates air refractivity, incorporating density, dispersion, CO2, and water vapor effects. This advancement is crucial for precise measurements in metrology laboratories within the visible spectrum.

Keywords:

Air density index of refraction of air refractivity of air wavelength of light in air

More Related Videos

Employing the Forced Oscillation Technique for the Assessment of Respiratory Mechanics in Adults

Employing the Forced Oscillation Technique for the Assessment of Respiratory Mechanics in Adults

Published on: February 9, 2022

Evaluation of Respiratory System Mechanics in Mice using the Forced Oscillation Technique

Evaluation of Respiratory System Mechanics in Mice using the Forced Oscillation Technique

Published on: May 15, 2013

Related Experiment Videos

Last Updated: Oct 19, 2025

Rapid Viscoelastic Characterization of Airway Mucus Using a Benchtop Rheometer

Rapid Viscoelastic Characterization of Airway Mucus Using a Benchtop Rheometer

Published on: April 21, 2022

Employing the Forced Oscillation Technique for the Assessment of Respiratory Mechanics in Adults

Employing the Forced Oscillation Technique for the Assessment of Respiratory Mechanics in Adults

Published on: February 9, 2022

Evaluation of Respiratory System Mechanics in Mice using the Forced Oscillation Technique

Evaluation of Respiratory System Mechanics in Mice using the Forced Oscillation Technique

Published on: May 15, 2013

Area of Science:

Physics
Metrology
Optical Science

Background:

Accurate air refractivity is essential for precision measurements.
Existing models like Edlén's formula provide a basis but can be complex.
Environmental factors such as CO2 and water vapor influence air's refractive index.

Purpose of the Study:

To develop a simplified equation for calculating air refractivity.
To integrate key factors affecting air refractivity into a single model.
To assess the accuracy and uncertainty of the new equation.

Main Methods:

Combined Jones' air density equation with Edlén's dispersion formula.
Incorporated Edlén's empirical expressions for CO2 and water vapor effects.
Estimated uncertainties associated with the refractivity calculations.

Main Results:

A simplified equation for air refractivity was successfully derived.
The simplified equation shows excellent agreement with Edlén's formulation under typical laboratory conditions.
The equation's validity was confirmed in the visible light spectrum.

Conclusions:

The simplified equation provides a reliable and accessible method for determining air refractivity.
This new equation is suitable for applications in metrology and other fields requiring precise optical path calculations.
The findings contribute to improved accuracy in optical measurements affected by atmospheric conditions.