Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Pressure Relationships in Thoracic Cavity01:24

Pressure Relationships in Thoracic Cavity

Breathing, otherwise known as pulmonary ventilation, is the process of air movement into and out of the lungs. The main mechanisms propelling pulmonary ventilation are atmospheric pressure (Patm), intra-pulmonary (Ppul ) or intra-alveolar pressure (Palv) within the alveoli, and intrapleural pressure (Pip) within the pleural cavity.
Breathing Mechanisms
Both intra-alveolar and intrapleural pressures rely on specific lung properties. The ability to breathe—allowing air to enter the lungs during...
Pulmonary Ventilation: Inhalation01:24

Pulmonary Ventilation: Inhalation

Pulmonary ventilation is a vital process that ensures the exchange of oxygen and carbon dioxide in the lungs. It refers to the movement of air into and out of the lungs, enabling the body to obtain oxygen and remove waste carbon dioxide. In this article, we will explore the intricacies of pulmonary ventilation, including its underlying principles, mechanisms, and the interplay of pressures within the respiratory system.
Boyle's law becomes particularly pertinent when examining respiratory...
Pulmonary Cycle: Exhalation01:17

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...
Hyperpnea and Hyperventilation01:25

Hyperpnea and Hyperventilation

Hyperventilation refers to a higher-than-normal rate and depth of breathing, often associated with anxiety attacks. This excessive breathing surpasses the body's need to expel CO2, leading to a condition known as hypocapnia - an unusually low level of carbon dioxide in the blood. Hypocapnia can constrict cerebral blood vessels, reducing blood flow to the brain, which may result in dizziness or fainting. Early signs include tingling and muscle spasms in the hands and face, caused by falling...
Acute Respiratory Failure-IV01:23

Acute Respiratory Failure-IV

Respiratory failure can manifest suddenly or gradually, characterized by a rapid decline in PaO2 and a rapid rise in PaCO2. This situation indicates a severe respiratory problem that may quickly become a life-threatening emergency. One of the early signs of hypoxemic Acute Respiratory Failure (ARF) is a change in mental status due to the brain's sensitivity to oxygen levels and changes in acid-base balance. Symptoms such as restlessness, confusion, and agitation suggest inadequate oxygen...
Pneumothorax II: Pathophysiology01:08

Pneumothorax II: Pathophysiology

Pneumothorax means the presence of air in the pleural space — the thin potential gap between the visceral and parietal pleura. This condition disrupts the normal pressure balance that keeps the lungs inflated, leading to partial or complete collapse of the affected lung.Normal physiologyUnder normal conditions, the pleural space maintains a slightly negative intrapleural pressure, which keeps the lungs expanded against the chest wall. This negative pressure creates a delicate balance between...

You might also read

Related Articles

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

Sort by
Same author

A sudden change and recovery in the magnetic environment around a repeating fast radio burst.

Science (New York, N.Y.)·2026
Same author

[Risk factors of delirium after Sun's procedure for acute type A aortic dissection and its influence on patients' prognosis].

Zhonghua yi xue za zhi·2025
Same author

Identification of immunogenic outer membrane vesicle vaccine antigen components using a meningococcal protein microarray.

Vaccine·2025
Same author

A bright burst from FRB 20200120E in a globular cluster of the nearby galaxy M81.

Nature communications·2024
Same author

The effects of falls on the prediction of osteoporotic fractures: epidemiological cohort study.

Archives of osteoporosis·2021
Same author

Beyond availability: the importance of routine videolaryngoscopy and institution-based rescue methods of difficult videolaryngoscopy.

British journal of anaesthesia·2017

Related Experiment Video

Updated: Jul 23, 2026

Assessing Cerebral Autoregulation via Oscillatory Lower Body Negative Pressure and Projection Pursuit Regression
11:26

Assessing Cerebral Autoregulation via Oscillatory Lower Body Negative Pressure and Projection Pursuit Regression

Published on: December 10, 2014

Cardiorespiratory response to lower body negative pressure

C M Chang1, Y Cassuto, D R Pendergast

  • 1Hermann Rahn Laboratory for Environmental Physiology, Department of Physiology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo 14214.

Aviation, Space, and Environmental Medicine
|July 1, 1994
PubMed
Summary

Lower body negative pressure (LBNP) significantly reduces cardiovascular function, including cardiac output and stroke volume, at -15 mm Hg. Higher LBNP levels beyond -35 mm Hg exceed physiological limits, causing further reductions and blood pressure drops.

Keywords:
NASA Discipline CardiopulmonaryNon-NASA Center

More Related Videos

Integrated Compensatory Responses in a Human Model of Hemorrhage
07:57

Integrated Compensatory Responses in a Human Model of Hemorrhage

Published on: November 20, 2016

Normothermic Negative Pressure Ventilation Ex Situ Lung Perfusion: Evaluation of Lung Function and Metabolism
09:31

Normothermic Negative Pressure Ventilation Ex Situ Lung Perfusion: Evaluation of Lung Function and Metabolism

Published on: February 14, 2022

Related Experiment Videos

Last Updated: Jul 23, 2026

Assessing Cerebral Autoregulation via Oscillatory Lower Body Negative Pressure and Projection Pursuit Regression
11:26

Assessing Cerebral Autoregulation via Oscillatory Lower Body Negative Pressure and Projection Pursuit Regression

Published on: December 10, 2014

Integrated Compensatory Responses in a Human Model of Hemorrhage
07:57

Integrated Compensatory Responses in a Human Model of Hemorrhage

Published on: November 20, 2016

Normothermic Negative Pressure Ventilation Ex Situ Lung Perfusion: Evaluation of Lung Function and Metabolism
09:31

Normothermic Negative Pressure Ventilation Ex Situ Lung Perfusion: Evaluation of Lung Function and Metabolism

Published on: February 14, 2022

Area of Science:

  • Cardiovascular Physiology
  • Human Physiology

Background:

  • Lower body negative pressure (LBNP) is a model used to simulate hypovolemia and study cardiovascular responses.
  • Understanding the limits of cardiovascular compensation during simulated hypovolemia is crucial for physiological research.

Purpose of the Study:

  • To investigate the cardiovascular effects of graded lower body negative pressure (LBNP) in humans.
  • To determine the threshold at which LBNP elicits significant cardiovascular changes and exceeds physiological compensation.

Main Methods:

  • Ten human subjects were exposed to various levels of supine LBNP (-8 to -45 mm Hg) in a randomized order.
  • Measurements included leg blood flow, cardiac output (Q), stroke volume (SV), heart rate, and blood pressure.
  • Cardiovascular parameters were assessed during 20-minute LBNP applications with 15-minute recovery periods.

Main Results:

  • Significant reductions in leg blood flow, cardiac output (Q), stroke volume (SV), and estimated lung blood volume were observed at -15 mm Hg LBNP.
  • Increasing LBNP to -35 mm Hg did not cause further significant changes in these parameters.
  • At -45 mm Hg LBNP, Q and SV decreased further, heart rate increased, and mean arterial pressure was maintained by increased vascular resistance up to -35 mm Hg, but dropped progressively at higher levels.

Conclusions:

  • LBNP up to -35 mm Hg can be compensated by physiological mechanisms, primarily increased vascular resistance.
  • Levels of LBNP at -45 mm Hg exceed the body's compensatory capacity, leading to a progressive decline in blood pressure.
  • These findings highlight the physiological limits of cardiovascular adaptation to simulated hypovolemia.