Name: how alveoli enable gas exchange
Uploaded: 2024-09-12T13:22:45.000Z
Duration: 1 min 26 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

Alveoli and Alveolar Ducts

폐소엽 내에서 말단 세기관지는 미세한 호흡 세기관지로 분기하여 공기를 폐의 호흡 부위로 전도합니다.
이 세기관지는 폐포관(alveolar ducts)으로 알려진 단순한 편평 상피가 늘어선 여러 관으로 더 나뉘며, 이 관은 폐포낭(alveolar sac)이라고 하는 포도 같은 구조로 끝납니다.
폐포는 이러한 폐포낭 내의 확장된 상피 구조입니다.
모든 폐포는 폐포와 호흡기 세기관지의 위치를 안정화하기 위해 둘러싸고 있는 탄성 섬유가 있는 광범위한 모세혈관 네트워크로 덮여 있습니다.
폐포벽에는 가스 교환을 촉진하는 수많은 편평 폐 상피 세포(I형 폐포 세포 또는 I형 폐포 세포)가 있습니다.
폐포 벽에는 또한 II형 폐포세포, II형 폐포 세포 또는 중격 세포라고 하는 직육면체 상피 세포가 있습니다. 이 세포는 주로 계면활성제로 구성된 폐포액을 분비하여 폐포 붕괴를 방지합니다.
폐포 벽에는 폐포 대식세포 또는 먼지 세포가 있어 흡입된 병원체와 미세한 먼지를 제거하는 데 도움이 됩니다.
각 폐에는 약 1억 5천만 개의 폐포가 있어 폐에 해면질 같은 질감을 줍니다.

폐포와 폐포관

인체의 호흡 영역은 전도 영역과 대조적으로 가스 교환에 적극적으로 참여하는 구조로 구성되어 있습니다. 이 영역의 시작은 말단 기관지가 호흡 기관지로 수렴하는 것으로 표시되며, 호흡 기관지는 가장 작은 기관지 분류입니다. 호흡 기관지는 폐포관으로 이어지고, 폐포관은 폐포 집합체로 열립니다. 가스 교환에 적극적으로 참여하는 폐포는 포도송이와 비슷한 작은 주머니와 비슷하며, 모두 폐포관과 복잡하게 연결되어 있습니다.

또한, 폐포낭은 단순히 여러 개의 개별 폐포가 모인 것입니다. 단일 폐포의 직경은 약 200μm이며, 탄력성이 있어 흡입 시 확장할 수 있습니다. 인접한 폐포는 폐포 모공을 통해 서로 연결되어 있으며, 이는 폐포와 폐 전체에 균일한 기압을 보장하는 작은 구멍입니다.

폐포 벽은 세 가지 주요 세포 유형으로 구성되어 있습니다. I형, II형, 폐포 대식세포입니다. I형 폐포 세포는 I형 폐포 세포라고도 하며, 폐포 표면의 최대 97%를 형성하는 편평 상피 세포로, 두께는 약 25nm이고 가스 투과성이 높습니다. I형 세포 사이에는 II형 폐포 세포(II형 폐포 세포 또는 중격 세포라고도 함)가 분산되어 있으며, 폐 표면 활성제, 즉 물의 표면 장력을 감소시켜 폐포 붕괴를 방지하는 인지질과 단백질 혼합물을 분비합니다. 면역 체계 식세포인 폐포 대식세포는 폐포 벽을 순찰하여 폐포로 들어오는 파편이나 병원균을 제거합니다.

I형 폐포 세포가 형성하는 매우 얇은 상피에 똑같이 얇고 탄력 있는 기저막이 붙어 있습니다. 이 막은 모세혈관의 내피막 경계를 형성합니다. 폐포막과 모세혈관막의 조합은 두께가 약 0.5μm(마이크로미터)인 호흡막을 생성합니다. 이 호흡막은 실제 가스 교환이 일어나는 곳입니다. 가스의 간단한 확산을 용이하게 하여 산소가 혈액에 흡수되어 운반되고 동시에 CO_2가 폐포 공기로 방출됩니다.

폐소엽 내에서 말단 세기관지는 미세한 호흡 세기관지로 분기하여 공기를 호흡 영역으로 전도합니다.

Education

교육

JoVE Core

Anatomy and Physiology

해부학 및 생리학

Unit 1

제1단원

The Respiratory System

호흡기계

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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 alveoli are linked by alveolar pores. These are small openings that help keep air pressure even across the alveoli and lungs. The alveolar wall also contains three main cell types: type I cells, type II cells, and alveolar macrophages.

Type I alveolar cells, also called type I pneumocytes, are flat epithelial cells. They cover up to 97 percent of the alveolar surface and are only about 25 nm thick, which makes them highly permeable to gases. Type II alveolar cells, also called type II pneumocytes or septal cells, release pulmonary surfactant, a mix of phospholipids and proteins that lowers water surface tension and helps prevent alveolar collapse. Alveolar macrophages act as phagocytic immune cells and remove debris or pathogens that reach the alveoli.

A very thin, elastic basement membrane lies under the type I cells. It meets the endothelial membrane of the capillaries. Together, these layers form the respiratory membrane, which is about 0.5 μm thick. This is the site of simple diffusion, where oxygen moves into the blood for transport and carbon dioxide moves into the alveolar air.

How Alveoli Enable Gas Exchange

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

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 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

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 alveoli, alveolar ducts, and the respiratory membrane work together to move oxygen into blood and release carbon dioxide in the lungs.

How Alveoli Enable Gas Exchange | 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.14.43

Major Organs of the Digestive System

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Peritoneum

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histology-of-the-gastrointestinal-gi-tract

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Blood Supply to the Digestive System

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Oral Cavity

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Tongue

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Salivary Glands and Saliva

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Teeth

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Tooth Anatomy

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The crown is visible above the gingivae and is protected by enamel.
...

Esophagus

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Cirrhosis is a liver ...

Intestinal Phase of Digestion

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In contrast, the arrival ...

Pancreas

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

Mucosal Barrier of the Stomach

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These cells first synthesize carbonic acid, which ...

Pancreatic Juice and Secretion

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Gross Anatomy of the Liver

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It is wedge-shaped and located more in the right hypochondriac and ...

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

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Large Intestine

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Bile

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digestive-functions-of-the-large-intestine

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Absorption of Nutrients

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Feces Formation and Defecation

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The incompetence of the lower esophageal sphincter results in the ...

Digestive System

Content elaboration: The digestive system consists of the gastrointestinal tract (alimentary canal) as well as various accessory organs including the teeth, tongue, salivary glands, liver, gallbladder and pancreas. The digestive system processes and supplies the molecules needed to sustain the living tissues within the body through the absorption of nutrients. Six major functions of the digestive system include secretion, ingestion, mechanical processing, enzymatic digestion, absorption and excretion. The lining of the digestive system protects surrounding tissues from the mechanical and enzymatic stresses of the digestive process. Processes of the digestive system include the mechanical and chemical breakdown of food into small molecules which are then absorbed by the digestive tract. Specific actions within the digestive system include mastication, peristalsis, segmentation and the release of hormones and enzymes necessary for digestion. The metabolic functions of the accessory organs play strategic roles in the breakdown of food products, the maintenance of glucose levels within the blood and the regulation of homeostasis in the body. Indigestible material is excreted as waste. Homeostatic imbalances are explored. These include, but are not limited to, conditions such as gallstones, heartburn, ulcers, dehydration, diarrhea, cirrhosis and cancers of the digestive system. Investigations are used to understand and explain the digestive system in a variety of inquiry and design scenarios that can incorporate evolutionary concepts, scientific reasoning, comparative analysis, communication skills and real-world applications.

Digestive System

Overview of Respiratory System

The respiratory system includes both upper and lower respiratory organs.
The upper respiratory organs consist of the nose and nasal cavity, paranasal ...

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.

How Alveoli Enable Gas Exchange

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