Name: how the body pushes air out
Uploaded: 2024-06-20T13:02:58.000Z
Duration: 1 min 23 s
Channel: JoVE

L’expiration commence lorsque les muscles inspiratoires se détendent, ce qui fait que l’air sort de la zone conductrice vers l’environnement extérieur.
Le relâchement du diaphragme provoque la contraction de la cavité pleurale et exerce une pression sur les poumons.
Lorsque le volume pulmonaire diminue, il comprime les alvéoles et augmente la pression alvéolaire.
Lorsque la pression alvéolaire dépasse la pression atmosphérique, l’air s’écoule.
La cavité pleurale offre un espace sans friction pour que le poumon puisse se dilater et se contracter pendant la respiration.
De plus, l’expiration résulte du recul élastique des poumons et n’implique aucune contraction musculaire.
Lors de l’expiration laborieuse, les muscles abdominaux poussent le diaphragme vers l’avant, provoquant la contraction de la cavité thoracique ; simultanément, les muscles intercostaux internes abaissent la cage thoracique et diminuent le volume thoracique.
L’expiration peut être volontaire ou involontaire.
Dans l’expiration volontaire, l’air dans les poumons est retenu et libéré à un rythme fixe, par exemple, une expiration contrôlée pendant la parole.
À l’inverse, l’expiration involontaire est vitale pour les fonctions métaboliques et n’est pas sous contrôle conscient, comme la respiration pendant le sommeil.

mécanisme de respiration ii : expiration

Mechanism of Breathing II: Expiration

La physiologie de l'expiration : un processus respiratoire fluide
L'expiration, ou expiration, est un processus physiologique complexe qui commence lorsque les muscles inspiratoires commencent à se détendre. Cette relaxation déclenche une série d’événements qui symbolisent l’efficacité du système respiratoire.

Mécanisme d'expiration :

<ol style="padding-left: 35px; margin: 0;">
 <li style="margin: 8px 0;">Relaxation du diaphragme : À mesure que le muscle du diaphragme, acteur clé de ce processus, se détend, il se déplace vers le haut, réduisant ainsi le volume de la cavité thoracique. La relaxation de ce muscle critique est le principal moteur de la phase initiale de l'expiration.</li>
 <li style="margin: 8px 0;">Augmentation de la pression pleurale : La cavité pleurale se contracte après le relâchement du diaphragme. Cette contraction exerce une pression sur les poumons, provoquant une diminution du volume pulmonaire. Les muscles intercostaux, situés entre les côtes, se contractent également lors de l'expiration. Cette action tire les côtes vers le bas et vers l’intérieur, diminuant encore davantage la taille de la cavité thoracique.</li>
 <li style="margin: 8px 0;">Compression des alvéoles : À mesure que le volume pulmonaire diminue, les alvéoles sont comprimées, ce qui augmente la pression alvéolaire. Cette pression devient supérieure à la pression atmosphérique à l’extérieur du corps.</li>
 <li style="margin: 8px 0;">Flux d'air hors des poumons : La pression interne plus élevée chasse l'air des poumons, facilitant ainsi un écoulement fluide et sans effort.</li>
 </ol>

 La cavité pleurale, un espace entre les poumons et la paroi thoracique, agit comme une scène finement réglée, accueillant l'expansion et la contraction rythmiques des poumons au cours du cycle respiratoire. L'effort musculaire et le recul élastique naturel du tissu pulmonaire facilitent également l'expiration, aidant ainsi à expulser l'air des poumons.

 Expiration active : lors d'une respiration vigoureuse ou d'activités nécessitant une expiration forcée, comme chanter, jouer d'instruments à vent ou un effort physique intense comme l'haltérophilie, des muscles supplémentaires entrent en jeu :

 <ul style="padding-left: 35px;">
 <li style="list-style-type: disc; margin: 8px 0;">Muscles abdominaux : Ces muscles se contractent pour pousser le diaphragme plus haut, intensifiant ainsi la réduction du volume thoracique.</li>
 <li style="list-style-type: disc; margin: 8px 0;">Muscles intercostaux internes : ces muscles aident à abaisser la cage thoracique, réduisant ainsi davantage le volume thoracique et favorisant une expiration plus forte.</li>
 </ul>

 Expiration volontaire ou involontaire : Comprendre cette distinction est crucial pour saisir toute la complexité du processus respiratoire.

 <ul style="padding-left: 35px;">
 <li style="list-style-type: disc; margin: 8px 0;">Expiration volontaire : ce type d'expiration, comme pendant la parole ou le chant, implique un contrôle conscient de la respiration pour réguler avec précision le flux d'air.</li>
 <li style="list-style-type: disc; margin: 8px 0;">Expiration involontaire : ce processus automatique est crucial pour maintenir la vie, fonctionnant en continu sans effort conscient, même pendant le sommeil.</li>
 </ul>

Mécanisme de respiration II : Expiration

La physiologie de l’expiration : un processus respiratoire sans faille
L’expiration, ou expiration, est un processus physiologique complexe qui commence par l’inspiration ...

Education

Enseignement

JoVE Core

Nursing

Soins infirmiers

Unit 1

Unité 1

Vital Signs: Respiration

Signes vitaux : Respiration

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

how the body pushes air out

Expiration is the process of pushing air out of the lungs. It begins when the inspiratory muscles relax. That relaxation starts a chain of changes in the chest and lungs.

As the diaphragm relaxes, it moves upward. This lowers the volume of the thoracic cavity, or chest space. The pleural cavity also contracts and presses on the lungs.

The intercostal muscles, which sit between the ribs, help during this phase too. They pull the ribs downward and inward. This makes the chest cavity even smaller. As lung volume drops, the alveoli, or tiny air sacs, are compressed.

When the alveoli are compressed, alveolar pressure rises. It becomes higher than the atmospheric pressure outside the body. Air then moves out of the lungs. The pleural cavity supports this rhythmic expansion and contraction, and the elastic recoil of lung tissue also helps exhalation.

Some expiration is active and needs extra muscle effort. This happens during forced breathing, such as singing, playing wind instruments, or heavy exercise like weightlifting. In these cases, the abdominal muscles push the diaphragm farther up, and the internal intercostal muscles lower the rib cage to make expiration more forceful.

Expiration can also be voluntary or involuntary. Voluntary expiration is under conscious control, such as during speech or singing, when airflow must be carefully regulated. Involuntary expiration happens automatically and continues without conscious effort, even during sleep.

How the Body Pushes Air Out

respiration

Respiratory System and Gas Exchange

The respiratory system supports energy production by bringing oxygen into the body and removing carbon dioxide. In human cells, oxidation uses food molecules and oxygen to produce carbon dioxide and water. This process helps sustain life and depends on the respiratory system. Air moves through a pathway that includes the nose, oropharynx, larynx, trachea, bronchi, bronchioles, and lungs. Air enters through the nose and mouth, passes through the pharynx, and then moves through the larynx, which...

physiological control of respiration

How the Brain Regulates Breathing

How the brain regulates breathing is controlled by the respiratory center in the brainstem. This center manages involuntary breathing, so respirations continue without conscious effort and stay smooth and steady. Ventilation is maintained by monitoring carbon dioxide (CO2), oxygen (O2), and hydrogen ion concentration, or pH, in arterial blood. CO2 is the most important signal in this control system. When CO2 rises, the respiratory control system increases the rate and depth of breathing so...

respiration and gaseous exchange

How Heart and Lungs Exchange Gases

Heart and lung function work together to move oxygen and carbon dioxide through the body. This gas exchange depends on the cardiovascular system, which includes the heart and blood vessels, and on the respiratory system, which brings air to the alveoli and removes waste gases. The heart is a cone-shaped muscular pump at the center of this system. It has four chambers: two atria on top and two ventricles below. The atria receive blood from veins, including the superior and inferior vena cava...

mechanism of breathing i: inspiration

How Air Moves Into the Lungs

Air enters the lungs through a coordinated breathing process called inspiration, or inhalation. This is the first phase of the respiratory cycle. The respiratory system includes the conducting zone and the respiratory zone, and both help move air toward the place where gas exchange occurs. During inspiration, air comes in through the nose or mouth and passes through the conducting zone. This pathway includes the nasal cavity, trachea, and bronchi. These structures filter, warm, and humidify...

mechanism of breathing ii: expiration

Expiration is the process of pushing air out of the lungs. It begins when the inspiratory muscles relax. That relaxation starts a chain of changes in the chest and lungs. As the diaphragm relaxes, it moves upward. This lowers the volume of the thoracic cavity, or chest space. The pleural cavity also contracts and presses on the lungs. The intercostal muscles, which sit between the ribs, help during this phase too. They pull the ribs downward and inward. This makes the chest cavity even...

mechanism of breathing iii: the accessory muscles

mechanism-of-breathing-iii-the-accessory-muscles

Accessory Muscles That Support Breathing

Accessory muscles help the respiratory system expand the chest and move air when breathing needs extra effort. The diaphragm is still the main breathing muscle, but other muscles can assist during inhalation and exhalation. This support becomes important during deep breathing or when the body faces breathing challenges. Several accessory muscles help with inhalation. The sternocleidomastoid, which is in the neck, lifts the sternum and helps the chest cavity expand. The scalene muscles also sit...

factors affecting respiration

How Breathing Changes in Different Conditions

Respiration changes with age, activity, health, and the environment. It is the process of exchanging oxygen (O2) and carbon dioxide (CO2) between the body and the surroundings. Many factors can alter how fast and how deeply a person breathes. Newborns usually breathe faster than older children and adults. Their respiratory rate can range from thirty to sixty breaths per minute because their metabolic needs are higher. As people age, metabolic rate often decreases, and breathing tends to slow. <br...

respiratory assessment: purpose and indications

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Breathing Checks in Patient Monitoring

Respiratory assessment is a key part of patient monitoring in nursing. It helps detect early signs of clinical deterioration. Breathing changes often appear before other signs of worsening health, so nurses watch respiratory rate, breathing pattern, and breath sounds closely. A complete respiratory assessment goes beyond counting breaths. It includes inspection, which means looking at chest symmetry, effort, and use of accessory muscles. It also includes palpation, or feeling for tenderness,...

assessment of airway, skin color, and use of accessory muscles

assessment-of-airway-skin-color-and-use-of-accessory-muscles

Respiratory Signs to Check During Breathing

Respiratory assessment starts with checking the airway, skin color, and use of accessory muscles during breathing. These signs give quick clues about respiratory status and possible complications. A clear airway, normal skin color, and no accessory muscle use usually point to effective oxygenation and perfusion. Airway assessment is an important first step in any health check. Clinicians look for anything that could block breathing, such as vomit, a foreign object, or the tongue. In a...

assessment of ventilation i: respiratory rate

assessment-of-ventilation-i-respiratory-rate

Checking Breathing Patterns and Respiratory Rate

Ventilation assessment helps monitor a patient’s health status by checking breathing patterns and respiratory rate. Respiration is one of the easiest vital signs to observe. It can also show problems in several body systems, including serious issues such as brainstem injury after head trauma. Accurate assessment depends on unobtrusive observation. The patient should not know they are being watched, because awareness can change breathing patterns. A full evaluation also considers the patient’s...

assessment of ventilation ii: respiratory depth and rhythm

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Watching Breathing Depth and Rhythm

Breathing depth and rhythm help show how a person is ventilating. Respiratory depth is the amount of air inhaled or exhaled in one breath. It may be shallow or deep, and it usually stays steady when a person is resting or asleep. A deep sigh is an automatic deep breath that fills the lungs with more air than normal breathing. Respiratory depth is checked by watching chest excursion, or chest movement. Deep respiration shows full lung expansion and complete exhalation. Shallow respiration moves...

assessment of diffusion and perfusion

Gas Exchange Checks in Respiratory Care

Gas exchange checks in respiratory care focus on diffusion, perfusion, oxygen saturation, and capnography. These measures help show how well the lungs and blood vessels move oxygen in and remove carbon dioxide from the body. Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration. In the lungs, oxygen diffuses from the alveoli, the tiny air sacs, into the bloodstream. Carbon dioxide, which is made during cell metabolism, moves from the...

respiratory volumes and capacities i

Breathing Rates and Pattern Changes

Breathing rate and rhythm are important signs of respiratory health. A complete one-minute count helps show the patient’s breathing pattern. Even a small rise of three to five breaths per minute can be an early sign of respiratory distress. Patients with a rate above twenty-four breaths per minute need close monitoring for possible changes in body function. Normal and abnormal respirations have clear names. Eupnea means normal, gentle breathing with a regular rate and rhythm, usually twelve to...

alterations in respiration ii

Breathing Patterns and Their Clinical Meaning

Breathing patterns can be regular, deep, or shallow, and they can also become abnormal. These changes help explain how ventilation is affected in different conditions. Clinically, they are important because they can guide patient evaluation. Biot's breathing is irregular in both rate and depth. It alternates between deep gasping breaths and apnea, which is a pause in breathing. It may occur with increased intracranial pressure or damage to the brain's respiratory center, such as from stroke,...

respiratory volumes

Measuring Lung Air Volumes

Respiratory volumes measure how much air moves in and out of the lungs during breathing. These values help assess lung function, support diagnosis of respiratory conditions, and track overall respiratory health. Each measurement gives a different view of how the lungs work. Tidal volume (TV) is the air inhaled or exhaled in one normal breath. In adults, it is about 500 milliliters per breath. It serves as the baseline volume for resting breathing. Minute volume (MV) is the total air exchanged...

respiratory capacities

Lung Capacity Measures in Breathing

Lung capacity measures show how much air the respiratory system can move and hold during different parts of breathing. These measures help describe lung function in a more complete way. They are useful for understanding how the lungs work during inhaling and exhaling. Inspiratory capacity, or IC, is the maximum amount of air that can be inhaled with full effort. It is found by adding tidal volume and inspiratory reserve volume. IC usually ranges from 2.4 to 3.6 liters. Functional residual...

special considerations while measuring oxygen saturation

special-considerations-while-measuring-oxygen-saturation

Checking Breathing Rate and Oxygen Levels

Checking breathing rate and oxygen levels helps assess how well a patient is breathing. Respiratory rate is the number of breaths taken in one minute. Oxygen saturation shows how much oxygen is being delivered to the body’s tissues. Together, these signs give a fuller picture of respiratory function. The normal adult breathing rate is usually 12 to 20 breaths per minute. A lower rate may suggest respiratory depression or decreased oxygen levels. A rate above 20 breaths per minute may point to...

assessment of respiration

Respiratory Assessment Signs and Findings

Respiratory assessment looks at the signs and findings that show how well a person is breathing. It uses both subjective data and objective data to judge respiratory health. The respiratory system’s basic structures and main functions provide the basis for this check. Subjective assessment starts with an interview. Nurses ask about medical history, medicines, current symptoms, past respiratory problems like asthma or COPD, surgeries, and allergies. Family history also matters because it can...

key terms and concepts

Learn how expiration works as the diaphragm relaxes, chest volume drops, and air leaves the lungs. Includes active breathing and voluntary vs. involuntary exhalation.

How the Body Pushes Air Out | JoVE K12

JoVE Core Nursing offers concise animated lessons on nursing practices, covering health systems, nursing organizations, and health concepts. It includes practical communication, infection prevention, and nursing fundamentals, providing students with a clear understanding of nursing principles.

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How the Body Pushes Air Out

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