Name: gas exchange in lungs and tissues
Uploaded: 2024-09-12T13:22:46.000Z
Duration: 1 min 24 s
Channel: JoVE

K12 Standards

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

9-12

Human Anatomy and Physiology

Absorption And Excretion

Respiratory System

External and Internal Respiration

外呼吸涉及肺部肺泡与肺毛细血管之间氧气和二氧化碳的交换。
这种气体交换总是从较高分压区域向较低分压区域进行，即从 Phigh 到 Plow。
氧气从肺泡气中（PO2&#160; 为105 mmHg）扩散至肺毛细血管内的血液中（PO2为40 mmHg）。
同样，二氧化碳会从 PCO2 为 45 mmHg 的血液中扩散至 PCO2 为 40 mmHg 的肺泡气中。
在内呼吸过程中，氧气从体循环毛细血管转移至全身各处的组织细胞，而二氧化碳则从组织细胞转移至血液中。2 向相反方向移动。
体循环毛细血管的氧分压（PO2）高于组织细胞，因为细胞在产生ATP过程中消耗氧气，促使氧气从毛细血管扩散进入细胞。
相反，CO2 由活跃代谢产生的二氧化碳导致更高的PCO₂2 在细胞中的浓度高于全身毛细血管，导致CO2 从细胞扩散到这些毛细血管中。

外部和内部呼吸

外部呼吸发生在肺部，这是氧气在体内旅程的第一步。当我们吸气时，氧气进入肺部并扩散穿过薄薄的肺泡膜。肺泡是微小的充满空气的囊，为气体交换提供了巨大的表面积。肺泡中的氧气分压（105 毫米汞柱）高于相邻的肺毛细血管中的氧气分压（40 毫米汞柱），从而形成压力梯度。因此，氧分子从肺泡进入血液，与红细胞中的血红蛋白结合。

同时，作为细胞代谢废物产生的二氧化碳从血液进入肺泡。血液的 PCO_2 略高于肺泡空气中的 PCO_2（40 毫米汞柱），从而推动了这种交换。一旦交换完成，含氧血液就会返回心脏，泵送到全身，而二氧化碳则会在呼气时排出。

内部呼吸，也称为全身气体交换，发生在我们身体的组织层面。在这里，左心室泵送的含氧血液通过全身动脉，最终到达全身毛细血管。目标是为组织细胞提供氧气并收集其废物二氧化碳。全身毛细血管的 PO_2 高于组织细胞，因为氧气用于细胞中的 ATP 生成，促使氧气从毛细血管扩散到细胞中。相反，通过主动代谢（例如在细胞呼吸过程中）产生的二氧化碳会导致细胞中的 PCO_2 高于全身毛细血管中的 PCO_2，从而导致其从细胞扩散到这些毛细血管中。

影响内部和外部呼吸扩散速率的因素

分压梯度:分压差异越大，气体扩散速率就越快。肺泡空气中的 O_2 和 CO_2 分压也依赖于肺气流。某些药物（如吗啡）会减慢呼吸频率，从而减少 O_2 和 CO_2 交换。在高海拔地区，总大气压力和 O_2 分压都会下降，导致 O_2 扩散到血液中的速度变慢。由此产生的高原反应会导致呼吸困难、头痛、疲劳、失眠、恶心和头晕，因为血氧水平下降。

可用表面积:肺泡的巨大表面积和周围丰富的毛细血管使气体交换更加有效。减少这种表面积的情况（如肺气肿）会减慢交换速度。

扩散距离:薄的呼吸膜和红细胞通过狭窄毛细血管的单行通道使扩散距离最小化。肺水肿中可见的肺泡间质液积聚会延长扩散距离从而阻碍气体交换。

外呼吸涉及肺部肺泡与肺毛细血管之间的氧气和二氧化碳交换。  
这种气体交换始终……

Education

教育

JoVE Core

Anatomy and Physiology

解剖学与生理学

Unit 1

第 1 单元

The Respiratory System

呼吸系统

KEY TERMS AND CONCEPTS

关键术语与概念

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 exhalation.

After gas exchange in the lungs, oxygen binds to hemoglobin in red blood cells and oxygenated blood returns to the heart. The heart then pumps this blood through the body. Internal respiration, also called systemic gas exchange, happens at the tissues. Here, oxygen leaves the systemic capillaries and enters the cells, where it is used for ATP production. Carbon dioxide made during cellular metabolism moves from the cells into the capillaries because its partial pressure is higher in the tissues than in the blood.

The rate of diffusion depends on several factors. A larger partial pressure gradient increases gas movement, and lung airflow helps maintain the oxygen and carbon dioxide levels in alveolar air. Drugs such as morphine can slow breathing and reduce gas exchange. High altitude also lowers atmospheric pressure and oxygen partial pressure, which slows oxygen diffusion into the blood and can cause high-altitude sickness with breathlessness, headache, fatigue, insomnia, nausea, and dizziness.

Surface area and diffusion distance also affect how well respiration works. The many alveoli and surrounding capillaries create a large exchange surface, while emphysema can reduce that surface area and slow gas transfer. The thin respiratory membrane and narrow capillaries keep diffusion distance short. In pulmonary edema, extra interstitial fluid builds up around the alveoli and makes the diffusion path longer, which hinders gas exchange.

Gas Exchange in Lungs and Tissues

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...

nose and nasal cavity

How the Nose Filters and Senses Air

The nose filters, warms, moistens, and senses the air that enters the body. It also helps shape speech as sound vibrations pass through its large air spaces. The nose has an external part that is visible on the face and an internal part called the nasal cavity. The external nose is built from bone and hyaline cartilage, which gives it flexibility. It is covered by skin and muscle and lined with a mucous membrane. The frontal bone, nasal bones, and maxillary bone support this structure. The...

pharynx

Pharynx Pathways for Air and Food

The pharynx is a muscular tube lined with mucous membrane that connects the nasal cavities to the throat. It is divided into three parts: the nasopharynx, oropharynx, and laryngopharynx. Each part has a different role in moving air and food through the upper throat. The nasopharynx sits behind the nasal cavity and serves only as an air passage. Its upper region contains the pharyngeal tonsils, also called adenoids. These are clusters of lymphoid reticular tissue, similar to a lymph node, and...

larynx

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

Trachea: Layers, Rings, and Airflow

The trachea is the windpipe, and it is a key airway in the human respiratory system. It carries air between the larynx and the bronchi so oxygen can reach the lungs. About half of the trachea lies in the neck, and it sits in front of the esophagus. In an average adult, the trachea is about 10 to 12 cm long. It extends from the larynx at the level of the sixth cervical vertebra to the level of the fifth thoracic vertebra. Its wall is supported by C-shaped cartilaginous rings. The back side is...

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...

alveoli and alveolar ducts

How Alveoli Enable Gas Exchange

The respiratory zone of the human body is where gas exchange happens. It begins when the terminal bronchioles branch into respiratory bronchioles, the smallest bronchiole type. These then lead into alveolar ducts and finally into clusters of alveoli. Alveoli are tiny air sacs that look like bunches of grapes. They connect to alveolar ducts, and a group of alveoli forms an alveolar sac. A single alveolus is about 200 μm wide, and its elastic shape lets it expand during inhalation. Nearby...

gross anatomy of the lungs

Lung Lobes, Airways, and Blood Flow

The lungs are paired organs that connect to the trachea through the left and right bronchi. Their base rests against the diaphragm, the dome-shaped muscle below the lungs. The lungs are covered by the pleurae and sit next to the mediastinum, the central space in the chest. The right lung is shorter and wider than the left lung, and it has a larger volume. The left lung has a cardiac notch, which is an indentation for the heart. The top of each lung is the apex, and the lower part is the base.

pleura of the lungs

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...

pressure relationships in thoracic cavity

pressure-relationships-in-thoracic-cavity

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...

pulmonary ventilation: inhalation

Pulmonary Ventilation and Breathing Pressures

Pulmonary ventilation depends on breathing movements and the pressure changes that move air into and out of the lungs. It supports the exchange of oxygen and carbon dioxide by letting the body take in oxygen and remove waste carbon dioxide. Boyle's law is important here because changes in volume and pressure affect how air moves in the respiratory system. Several respiratory volumes help describe how much air the lungs move. Tidal volume is the air inspired or expired during normal, quiet...

pulmonary cycle: exhalation

Exhalation and Lung Pressure Changes

Exhalation is the process of expelling air from the lungs. It depends on pressure differences between the lungs and the atmosphere. During normal quiet breathing, exhalation is passive and does not require muscle contraction. The elastic recoil of the lungs and chest wall helps both structures return to their resting positions after inhalation. When the muscles used for inhalation stop working, the diaphragm and external intercostal muscles relax. The diaphragm moves upward, and the ribs move...

factors affecting pulmonary ventilation

What Changes Breathing Ease in the Lungs

Breathing ease in the lungs depends on alveolar surface tension, lung compliance, and airway resistance. These factors affect how hard it is to move air during pulmonary ventilation, along with the pressure difference between the outside environment and the lungs. Alveolar surface tension comes from the fluid lining the inside of the alveoli. Water molecules in this fluid attract each other more strongly than they attract the air, so the liquid tends to pull the alveoli inward. That force must...

respiratory volumes and capacities

Lung Volume Measurements in Breathing

Lung volume measurements show how air moves in and out of the respiratory system during breathing. They help explain how the body takes in oxygen and removes carbon dioxide. Respiratory volumes and capacities also give useful information about lung function. Tidal volume is the air breathed in and out during normal, quiet breathing. Inspiratory reserve volume is the extra air that can be forcefully inhaled beyond tidal volume. Expiratory reserve volume is the extra air that can be forcefully...

physical principles governing gas exchange

physical-principles-governing-gas-exchange

Gas Laws in Lung Gas Exchange

Gas laws explain how oxygen and carbon dioxide move during respiration. External respiration is the exchange of gases in the lungs. Oxygen diffuses into the blood, and carbon dioxide diffuses out. Internal respiration happens in body tissues, where the gases move in the opposite directions. Two gas laws guide this process: Dalton's law of partial pressures and Henry's law. Dalton's law says the total pressure of a gas mixture equals the sum of the pressures of each gas acting alone. The...

external and internal respiration

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

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...

carbon dioxide transport in the blood

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...

hypoxia

Hypoxia: Types and Carbon Monoxide Poisoning

Hypoxia is a medical condition in which body tissues do not get enough oxygen. It can cause a bluish color in the skin and mucosae, especially in fair-skinned people. This sign is often seen when hemoglobin (Hb) saturation drops below 75%. Hypoxia can happen for several different reasons. Anemic hypoxia occurs when there are too few red blood cells (RBCs) or when RBCs have abnormal or too little Hb. Ischemic hypoxia comes from poor blood circulation or blocked blood flow, so blood becomes...

neural control of respiration

Brainstem Centers That Control Breathing

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

How Blood Gases Control Breathing Rate

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

other-factors-affecting-respiration-centers

Respiratory Reflexes That Change Breathing

Breathing is controlled by the brainstem, but it can also be changed by the nervous system and by body signals. The cerebral motor cortex can override the medullary respiratory centers and send signals directly to the breathing muscles. This makes voluntary actions like holding your breath or taking deeper breaths possible. That control is limited. When carbon dioxide, or CO2, builds up in the blood to a critical level, the brainstem respiratory centers start breathing again. This is why a...

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 oxygen and carbon dioxide move in external and internal respiration, plus how pressure, surface area, and diffusion distance affect exchange.

Gas Exchange in Lungs and Tissues | 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.

Florida Department of Education

High School

Life Science

SC.912.L.14

SC.912.L.14.44

Major Organs of the Digestive System

The human digestive system consists of two major parts: the gastrointestinal &#8212; GI &#8212; tract and the accessory organs.
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Peritoneum

The peritoneum is the body&#39;s largest serous membrane enveloping the abdominal cavity.
It has two portions &#8212; the parietal and visceral peritoneum ...

histology-of-the-gastrointestinal-gi-tract

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...

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It can be divided into a broad head located ...

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Pancreatic Juice and Secretion

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As the swallowed food ...

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mechanical-and-chemical-digestion-in-the-small-intestine

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digestive-functions-of-the-large-intestine

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Digestive System

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Digestive System

Overview of Respiratory System

The respiratory system includes both upper and lower respiratory organs.
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Respiratory System

Content elaboration: The respiratory system is comprised of the airways, lungs and diaphragm. The airways include the nasal and oral cavities, pharynx, larynx, trachea, bronchi, bronchioles and alveoli. The respiratory system transports and exchanges gases including oxygen and carbon dioxide. Processes involved in the respiratory system include respiration mechanics and gas exchange. Respiration mechanics is the process by which humans breathe and includes the movement of the diaphragm and pressure-volume relationships. Gas exchange refers to the diffusion of gas across the alveolar epithelium in the respiratory system and capillary endothelium of the cardiovascular system. Lung volumes and capacities can be measured using spirometry. Homeostatic imbalances are explored. These include, but are not limited to, asthma, chronic obstructive pulmonary disease (COPD), tuberculosis, cystic fibrosis and the effects of smoking and pollution. Investigations are used to understand and explain the respiratory system in a variety of inquiry and design scenarios that can incorporate evolutionary concepts, scientific reasoning, comparative analysis, communication skills and real-world applications.

Gas Exchange in Lungs and Tissues

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