Name: how hemoglobin loads and releases oxygen
Uploaded: 2024-09-12T13:22:46.000Z
Duration: 1 min 27 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

Oxygen Transport in the Blood

La sangre transporta principalmente oxígeno unido a la hemoglobina en los glóbulos rojos, con un pequeño porcentaje disuelto en el plasma debido a su baja solubilidad en la sangre.
La hemoglobina, compuesta por cuatro cadenas polipeptídicas que contienen grupos hemo ricos en hierro, puede unirse a cuatro moléculas de oxígeno.
Como se ve en la curva de disociación, la unión del oxígeno a la hemoglobina está muy influenciada por la presión parcial del oxígeno o PO2 .
A medida que aumenta el PO2, más oxígeno se une a la hemoglobina.
Por esta razón, la hemoglobina en la sangre arterial rica en oxígeno está saturada en un 98% con oxígeno.
Al llegar a los capilares sistémicos, la saturación de oxígeno disminuye debido a una PO2 baja.
Varios factores fisiológicos influyen en la afinidad de la hemoglobina por el oxígeno.
Como se ve en este gráfico, un aumento de la temperatura celular disminuye esta afinidad.
Además, el efecto Bohr ocurre cuando los ionesP CO2 más altos y los iones H elevados disminuyen el pH de la sangre, favoreciendo la descarga de oxígeno de la hemoglobina.
Además, los glóbulos rojos producen 1,3-bisfosfoglicerato durante el metabolismo de la glucosa, lo que también aumenta la descarga de oxígeno de la hemoglobina.

transporte de oxígeno en la sangre

La hemoglobina (Hb) es una molécula crucial en el cuerpo humano, que consta de cuatro cadenas polipeptídicas, cada una unida a un grupo hemo que contiene hierro. Esta estructura única permite que la hemoglobina se una al oxígeno, y cada molécula es capaz de combinarse con cuatro moléculas de oxígeno, lo que produce una carga de oxígeno rápida y reversible. Cuando está completamente cargada de oxígeno, se denomina oxihemoglobina, mientras que la hemoglobina que ha liberado oxígeno se denomina hemoglobina reducida o desoxihemoglobina. A medida que la hemoglobina se une al oxígeno, su forma cambia, lo que la hace más eficiente para captar moléculas de oxígeno adicionales. Esta adaptación estructural garantiza que el proceso de carga y descarga de oxígeno sea altamente eficiente.

La velocidad a la que la hemoglobina se une o libera oxígeno está regulada con precisión por varios factores, entre ellos la presión parcial de oxígeno (pO_2), la temperatura, el pH de la sangre, la presión parcial de dióxido de carbono (pCO_2) y la concentración de 2,3-bisfosfoglicerato (2,3-BPG) en la sangre. Estos factores trabajan juntos para garantizar un suministro adecuado de oxígeno a las células de los tejidos.

En condiciones normales de reposo, la hemoglobina de la sangre arterial suele estar saturada de oxígeno en un 98%, y cada 100 ml de sangre arterial sistémica contiene unos 20 ml de oxígeno, expresado como un 20% en volumen (porcentaje en volumen) de contenido de oxígeno. A medida que la sangre fluye a través de los capilares sistémicos, libera aproximadamente 5 ml de oxígeno por cada 100 ml de sangre, lo que da como resultado una saturación de Hb del 75% y un contenido de oxígeno del 15% en volumen en la sangre venosa. Esto significa que la sangre venosa aún conserva una reserva significativa de oxígeno que se puede utilizar cuando sea necesario.

Además de la pO_2, otros factores como la temperatura, el pH de la sangre, la pCO_2 y los niveles de BPG influyen en la saturación de hemoglobina a una PO_2 determinada. Los glóbulos rojos (RBC) producen 2,3-BPG durante el metabolismo de la glucosa, y sus niveles aumentan cuando los niveles de oxígeno son crónicamente bajos. Estos factores pueden modificar la estructura tridimensional de la hemoglobina, alterando en última instancia su afinidad por el oxígeno. El aumento de la temperatura, pCO_2, iones H^+ o niveles de 2,3-BPG en la sangre reduce la afinidad de la hemoglobina por el oxígeno, lo que facilita la liberación de oxígeno. Por el contrario, la disminución de estos factores aumenta la afinidad de la hemoglobina por el oxígeno.

Cabe destacar que estos factores suelen ser más altos en los capilares sistémicos, donde la descarga de oxígeno es esencial. A medida que las células metabolizan la glucosa y consumen oxígeno, producen dióxido de carbono, lo que aumenta los niveles de pCO_2 y H^+ en la sangre capilar. Esto debilita el enlace Hb-O_2, un fenómeno conocido como el efecto Bohr. Además, el aumento de la temperatura en los tejidos activos reduce la afinidad de la hemoglobina por el oxígeno, lo que mejora aún más la descarga de oxígeno.

Transporte de oxígeno en la sangre

La sangre transporta principalmente oxígeno unido a la hemoglobina en los glóbulos rojos, con un pequeño porcentaje disuelto en el plasma debido a su baja solubilidad en la sangre.
...

Education

Educación

JoVE Core

Anatomy and Physiology

Anatomía y Fisiología

Unit 1

Unidad 1

The Respiratory System

El sistema respiratorio

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

how hemoglobin loads and releases oxygen

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 up more oxygen molecules efficiently.

Several factors control how easily hemoglobin binds or releases oxygen. These include the partial pressure of oxygen (pO2), temperature, blood pH, partial pressure of carbon dioxide (pCO2), and the amount of 2,3-bisphosphoglycerate, or 2,3-BPG, in the blood. Together, these factors help make sure tissue cells get enough oxygen.

At rest, arterial blood is usually about 98% saturated with oxygen. In 100 mL of systemic arterial blood, there are about 20 mL of oxygen, which is described as 20 vol% oxygen content. As blood moves through systemic capillaries, it gives up about 5 mL of oxygen per 100 mL of blood. Venous blood then has about 75% hemoglobin saturation and about 15 vol% oxygen content, so it still carries an oxygen reserve.

Even at the same pO2, temperature, pH, pCO2, and BPG levels can change hemoglobin saturation. Red blood cells make 2,3-BPG during glucose metabolism, and its level rises when oxygen has been low for a long time. These changes alter hemoglobin’s three-dimensional shape and shift its affinity for oxygen.

Higher temperature, more pCO2, more H+ ions, or more 2,3-BPG lower hemoglobin’s affinity for oxygen and make release easier. Lower levels of these factors increase oxygen affinity. These conditions are usually strongest in systemic capillaries, where oxygen unloading is needed most.

As body cells use glucose and consume oxygen, they produce carbon dioxide. This raises pCO2 and H+ in capillary blood and weakens the hemoglobin-oxygen bond. This effect is called the Bohr effect. Increased temperature in active tissues also helps hemoglobin release oxygen more readily.

How Hemoglobin Loads and Releases Oxygen

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

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Voice Box Anatomy and Function

The larynx is the voice box in the neck. It carries air into the lungs and helps produce voice. Its structure is complex because it must support both breathing and sound production. The larynx contains cartilage, muscles, and the vocal cords, also called vocal folds. It includes three large unpaired cartilages: the thyroid, cricoid, and epiglottis. It also includes three paired cartilages: the arytenoids, corniculates, and cuneiforms. Ligaments and membranes hold these parts together. The...

trachea

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the bronchial tree

Bronchial Branching and Airflow Control

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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gross anatomy of the lungs

Lung Lobes, Airways, and Blood Flow

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Pleura Layers and Lung Protection

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pressure relationships in thoracic cavity

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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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respiratory volumes and capacities

Lung Volume Measurements in Breathing

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physical principles governing gas exchange

physical-principles-governing-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

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

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hypoxia

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neural control of respiration

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Breathing is controlled by nerve centers in the brainstem. These respiratory centers send nerve signals to the muscles that move the lungs. The main centers are in the medulla oblongata and the pons.

chemical factors affecting respiration centers

chemical-factors-affecting-respiration-centers

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Blood gases and blood pH help control breathing rate and depth. Changes in carbon dioxide, oxygen, and hydrogen ion levels in arterial blood are detected by chemoreceptors, which are special sensors in the body. Central chemoreceptors are found throughout the brain stem, including the ventrolateral medulla. Peripheral chemoreceptors are located in the aortic arch and carotid arteries. Together, these sensors help the respiratory system respond to chemical changes in the blood. Carbon dioxide...

other factors affecting respiration centers

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hyperpnea and hyperventilation

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

COPD is a lung condition that causes ongoing breathing problems. It leads to shortness of breath, cough, and sputum production because the airways become blocked and airflow is reduced. Smoking is the main risk factor for COPD, and more than 80% of patients have a history of it. People with COPD often develop worsening dyspnea, or labored breathing. They may also cough often and get repeated lung infections. Many patients with COPD can develop respiratory failure. This happens when...

other pulmonary disorders

Asthma, TB, Lung Cancer, and Sleep Apnea

Asthma, lung cancer, tuberculosis, and sleep apnea are major pulmonary disorders. They affect breathing in different ways. Some are chronic, some are infectious, and some can become life-threatening if not found and treated early. Asthma is marked by chronic airway inflammation and hypersensitivity. It can cause airway obstruction from bronchial spasms, mucosal edema, increased mucus secretion, or epithelial damage. Triggers vary and can include allergens or emotional upset. Treatment often...

key terms and concepts

Learn how hemoglobin in red blood cells binds oxygen, changes shape, and releases it in tissues. Explore the Bohr effect, BPG, pH, and CO2.

How Hemoglobin Loads and Releases Oxygen | JoVE K12

anatomy and physiology

JoVE Core Anatomy and Physiology showcases the anatomical and physiological details of the human body in comprehensive, clear, and engaging video animations. This collection of lessons focuses on the structures, components, functions, and requirements of the human body. It is complemented by scientist-in-action videos that demonstrate the application of this knowledge in real-world medical and research settings.

Alabama Course of Study Science

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From Molecules to Organisms: Structures and Processes

9-12.HA.1.9.a

9-12.HA.1.9.c

Florida Department of Education

High School

Life Science

SC.912.L.14

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Digestive System

How Hemoglobin Loads and Releases Oxygen

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