Name: how blood carries carbon dioxide
Uploaded: 2024-09-12T13:22:46.000Z
Duration: 1 min 19 s
Channel: JoVE

K12 Standards

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Ohio’s Learning Standards and Model Curriculum

9-12

Human Anatomy and Physiology

Absorption And Excretion

Respiratory System

Carbon Dioxide Transport in the Blood

Le dioxyde de carbone est transporté des tissus vers les poumons de trois manières.
Environ 7 à 10 % se déplacent dissous dans le plasma.
Plus de 20 % est lié à l’hémoglobine, formant de la carbaminohémoglobine déclenchée par un PCO2 relativement plus élevé dans les tissus.
À l’inverse, un taux de PCO2 relativement faible dans les capillaires pulmonaires provoque la dissociation de la carbaminohémoglobine, libérant du CO2. 
Le CO2 restant circule dans le sang sous forme d’ions bicarbonate.
La plupart du CO2 entrant dans les globules rouges est catalysé en acide carbonique par l’enzyme anhydrase carbonique. L’acide carbonique se dissocie ensuite en ions bicarbonate et hydrogène.
Les ions bicarbonate se diffusent rapidement hors des globules rouges.
En échange, les ions chlorure pénètrent dans les globules rouges par le décalage de chlorure pour neutraliser les charges dans les globules rouges.
Les ions bicarbonate voyagent avec le sang vers les poumons, où le faible taux de PCO2 déclenche leur retour dans les globules rouges. L’ensemble du processus s’inverse, libérant le CO2.

le transport du dioxyde de carbone dans le sang

Le transport du dioxyde de carbone (CO_2) dans le sang est essentiel à la physiologie humaine. En moyenne, les cellules de notre corps produisent environ 200 ml de CO2 par minute, soit exactement la quantité expulsée par les poumons. Ce processus implique le transport du CO2 des cellules tissulaires vers les poumons sous trois formes principales.

Les formes de transport du CO_2

<ol>
	<li>Dissous dans le plasma : Un petit pourcentage (7-10 %) de CO2 est transporté et dissous directement dans le plasma.</li>
	<li>Carbaminohémoglobine : Un peu plus de 20 % du CO_2 est chimiquement lié à l'hémoglobine, formant la carbaminohémoglobine. Dans ce processus, le CO_2 se lie directement aux acides aminés de la globine, et non à la partie hémique de l'hémoglobine. Les niveaux de pCO_2 influencent considérablement la formation de carbaminohémoglobine. Des niveaux élevés de pCO_2 dans les capillaires tissulaires favorisent la formation de carbaminohémoglobine, tandis que de faibles niveaux de pCO_2 dans les capillaires pulmonaires facilitent la séparation du CO_2 de la globine, lui permettant de pénétrer dans les alvéoles par diffusion.</li>
	<li>Ions bicarbonate (HCO_3^-) : Environ 70 % du CO_2 est transporté sous forme d'ions bicarbonate dans le plasma sanguin. Ce processus commence lorsque le CO_2 se diffuse dans les capillaires systémiques et pénètre dans les globules rouges, où il réagit avec l'eau sous l'influence de l'enzyme anhydrase carbonique pour former de l'acide carbonique. Cet acide se dissocie ensuite en H^ + et HCO_3-. Dans les poumons, le processus s'inverse et le CO_2 est libéré pour être expiré.</li>
</ol>

L'effet Haldane

La quantité de CO_2 transportée dans le sang est profondément affectée par le degré d'oxygénation du sang, connu sous le nom d'effet Haldane. Cet effet stipule qu'une pO_2 et une saturation en oxygène de l'hémoglobine plus faibles permettent au sang de transporter plus de CO_2 en raison d'une affinité accrue de l'hémoglobine pour le CO_2 dans ces conditions.

Résumé

Le transport du CO_2 dans le sang est un processus complexe mais efficace, qui implique principalement la formation d'ions carbaminohémoglobine et bicarbonate. Ce système complexe assure que l'organisme maintient un équilibre stable entre la production et l'expulsion du CO_2, ce qui témoigne des remarquables mécanismes de régulation de l'organisme, essentiels à un fonctionnement physiologique optimal.

Le transport du dioxyde de carbone dans le sang

Le dioxyde de carbone est transporté des tissus vers les poumons de trois manières.
Environ 7 à 10 % se déplacent dissous dans le plasma.
Plus de 20 % est lié à l’hémoglobine, formant ...

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The Respiratory System

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KEY TERMS AND CONCEPTS

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how blood carries carbon dioxide

Carbon dioxide is carried in the blood from body tissues to the lungs. Cells make about 200 mL of CO2 each minute, and the lungs remove about the same amount. The blood moves this waste gas in three main forms.

A small amount, about 7-10%, stays dissolved in the plasma. Just over 20% binds to hemoglobin and forms carbaminohemoglobin. In this case, CO2 attaches to the amino acids of globin, not to the heme part of hemoglobin.

The rest, about 70%, is carried as bicarbonate ions, or HCO3-. CO2 diffuses into systemic capillaries and enters red blood cells. There, carbonic anhydrase helps CO2 react with water to form carbonic acid, which then splits into H+ and HCO3-. In the lungs, the reaction reverses, and CO2 is released so it can be exhaled.

Blood CO2 transport also depends on oxygen levels. This relationship is called the Haldane effect. When pO2 is low and hemoglobin is less saturated with oxygen, blood can carry more CO2 because hemoglobin has a higher affinity for CO2 in those conditions.

How Blood Carries Carbon Dioxide

overview of respiratory system

How Breathing Moves Air and Gases

The respiratory system moves air in and out of the body and exchanges oxygen and carbon dioxide with the environment. This gas exchange is part of respiration, which is essential for life. The system supplies the blood with oxygen so it can carry that oxygen to the rest of the body. Breathing starts when air enters through the nose or mouth. The nose and nasal cavity form the main external opening and the first part of the airway. Air then passes through the pharynx, or throat, which is shared...

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Pharynx Pathways for Air and Food

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The bronchial tree carries air from the trachea into the lungs and helps control breathing. The trachea, or windpipe, connects the larynx to the bronchi. At the carina, the trachea splits into two primary bronchi. The right primary bronchus is wider, shorter, and more vertical than the left. Because of that shape, foreign objects and infections are more likely to enter the right lung. The carina is a cartilaginous ridge at the split in the airway. It helps keep the airway open. It also has...

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Lung Lobes, Airways, and Blood Flow

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Pleura Layers and Lung Protection

The pleura are membranes that protect the lungs inside the chest cavity. They are a type of serous membrane and wrap around each lung. The pleura have two layers: the visceral pleura and the parietal pleura. The visceral pleura covers the surface of the lung. The parietal pleura is the outer layer. It lines the thoracic wall, the mediastinum, and the diaphragm. The hilum is the point where the visceral and parietal layers connect. The space between these layers is called the pleural cavity. <br...

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How Pressure Drives Breathing in the Lungs

Breathing depends on pressure changes in the lungs, chest, and airways. Pulmonary ventilation is the movement of air into and out of the lungs. It is driven by atmospheric pressure, intra-alveolar pressure inside the alveoli, and intrapleural pressure in the pleural cavity. Inhalation and exhalation rely on pressure differences between the atmosphere and the lungs. Gas pressure comes from the movement of confined molecules. Boyle’s law explains that pressure and volume are inversely...

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Pulmonary Ventilation and Breathing Pressures

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pulmonary cycle: exhalation

Exhalation and Lung Pressure Changes

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factors affecting pulmonary ventilation

What Changes Breathing Ease in the Lungs

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respiratory volumes and capacities

Lung Volume Measurements in Breathing

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physical principles governing gas exchange

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Gas Laws in Lung Gas Exchange

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external and internal respiration

Gas Exchange in Lungs and Tissues

Gas exchange in the lungs and body tissues moves oxygen into the blood and removes carbon dioxide. External respiration happens in the lungs, where inhaled oxygen enters the alveoli, the tiny air sacs that provide a large surface area for diffusion. Oxygen moves across the thin alveolar membrane into the pulmonary capillaries because its partial pressure is higher in the alveoli than in the blood. At the same time, carbon dioxide moves in the opposite direction and is later breathed out during...

oxygen transport in the blood

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Hemoglobin is the main molecule that carries oxygen in blood. It is found in red blood cells and has four polypeptide chains, each attached to an iron-containing heme group. This structure lets one hemoglobin molecule bind up to four oxygen molecules quickly and reversibly. When hemoglobin is fully loaded with oxygen, it is called oxyhemoglobin. When it has released oxygen, it is called reduced hemoglobin, or deoxyhemoglobin. As hemoglobin binds oxygen, its shape changes, which helps it pick...

carbon dioxide transport in the blood

Carbon dioxide is carried in the blood from body tissues to the lungs. Cells make about 200 mL of CO2 each minute, and the lungs remove about the same amount. The blood moves this waste gas in three main forms. A small amount, about 7-10%, stays dissolved in the plasma. Just over 20% binds to hemoglobin and forms carbaminohemoglobin. In this case, CO2 attaches to the amino acids of globin, not to the heme part of hemoglobin. The rest, about 70%, is carried as bicarbonate ions, or HCO3-. CO2...

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neural control of respiration

Brainstem Centers That Control Breathing

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chemical factors affecting respiration centers

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How Blood Gases Control Breathing Rate

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other factors affecting respiration centers

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Respiratory Reflexes That Change Breathing

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Breathing Changes in Exercise and Anxiety

Breathing changes in exercise and anxiety can look similar, but they do not have the same cause. Hyperventilation is a higher-than-normal rate and depth of breathing. It often happens during anxiety attacks and can push out more carbon dioxide than the body needs to remove. When too much carbon dioxide is lost, the blood develops hypocapnia, which means an unusually low level of carbon dioxide. Hypocapnia can narrow cerebral blood vessels and reduce blood flow to the brain. This may cause...

chronic obstructive pulmonary disease

COPD Signs, Causes, and Lung Damage

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other pulmonary disorders

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key terms and concepts

Learn how carbon dioxide moves in the blood as dissolved gas, carbaminohemoglobin, and bicarbonate ions, plus how the Haldane effect affects transport.

How Blood Carries Carbon Dioxide | JoVE K12

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Digestive System

How Blood Carries Carbon Dioxide

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