Name: pulmonary ventilation and breathing pressures
Uploaded: 2025-05-22T09:06:19.000Z
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

Pulmonary Ventilation: Inhalation

呼吸是一个交替进行吸气和呼气的节律性过程。
平静吸气时，由于肺内气体压力降低，胸腔随之扩张，促使空气流入。
膈肌是吸气过程中最重要的肌肉。它收缩并下降约1厘米，同时变得扁平，从而增加胸腔的高度，产生约1至3毫米汞柱的压力差。
肋间外肌收缩时，会抬高肋骨并向上牵拉胸骨。
肋骨向外突出，使胸廓的横向和前后径扩大。
尽管胸腔尺寸仅变化几毫米，但胸腔容积却增加了约500 ml。
当胸腔容积增大时，肺内体积增加，导致肺内压比大气压降低约 1 mm Hg。
空气流入肺部，直到肺内压等于大气压。与此同时，胸膜腔内压相对于大气压下降至约 -6 mm Hg。

肺通气:吸气

肺通气是确保肺部氧气和二氧化碳交换的重要过程。它指的是空气进出肺部的运动，使身体能够获得氧气并清除废弃的二氧化碳。在本文中，我们将探讨肺通气的复杂性，包括其基本原理、机制以及呼吸系统内压力的相互作用。

在检查呼吸量和压力时，波义尔定律尤为重要。在肺通气的背景下，必须了解几个关键术语:

潮气量 (TV) :是指在正常呼吸过程中无需任何有意识努力即可吸入或呼出的空气量。

吸气储备量 (IRV) :是指能够在潮气量基础上，通过用力吸气额外吸入的最大空气量。

呼气储备量 (ERV):是指能够在潮气量基础上，通过用力呼气额外呼出的最大空气量。

残气量 (RV):最大呼气后肺部剩余的空气量。

这些呼吸量有助于计算肺活量等重要指标。

肺活量 (VC) :是潮气量、吸气储备量和呼气储备量的总和。

此外，呼吸量和压力之间的关系错综复杂。在正常吸气（吸入）过程中，横膈膜和肋间外肌收缩，使胸腔扩张。这种扩张会增加肺容量，导致肺内压降低，从而使空气从大气流入肺部。

吸气（吸入）的机制

吸入是由一系列相互关联的过程引起的，涉及横膈膜、肋间肌和胸腔扩张。让我们分解每个步骤:

<ol>
	<li>横膈膜收缩:在正常吸气过程中，主要涉及的肌肉是横膈膜。这种圆顶状、片状的肌肉将胸腔与腹腔分隔开来。当我们吸气时，横膈膜收缩变平，从而增加胸腔的容积。这一动作会产生负的肺内压，将空气吸入肺部。</li>
	<li>肋间肌参与:肋间肌是另一组参与吸气的重要肌肉。它们位于肋骨之间，分为外肋间肌和内肋间肌。
	<ul style="list-style-type: disc; margin-left: 35px;">
		<li> 外肋间肌:在吸气过程中，这些肌肉收缩，抬起并扩张肋骨。这一运动进一步增加了胸腔的容积，增强了空气的吸入。</li>
		<li> 内肋间肌:这些肌肉有助于深吸气和用力呼气。在用力吸气过程中，上部内肋间肌收缩，进一步抬高胸腔，从而使肺部扩张得更大。</li>
	</ul>
	</li>
	<li>胸腔扩张:随着横膈膜收缩和肋间肌的参与，胸腔向多个方向扩张。这种扩张降低了肺内的压力，在外部空气和呼吸系统内的空气之间产生了压力差。结果，空气冲进肺部，填满肺泡（微小的气囊）进行气体交换。</li>
</ol>

强制吸气:在体力消耗增加或需要增加氧气摄入量时，就会发生强制吸气。强制吸气的机制涉及额外的肌肉以最大限度地扩大肺部:

<ol>
	<li> 胸锁乳突肌:颈部的胸锁乳突肌在强制吸气中起着重要作用。当它被激活时，它会抬高胸骨，帮助进一步扩张胸腔。</li>
	<li> 斜角肌:斜角肌位于颈部两侧，在强制吸气过程中抬起上肋骨。它们的收缩有助于为肺部扩张创造更多的空间。</li>
	<li> 胸小肌:胸小肌位于胸大肌下方，有助于提升肋骨和扩大胸腔。</li>
</ol>

压力在肺通气中的作用

足够的肺通气依赖于三种不同压力之间的相互作用:

<ol>
	<li> 肺内压:也称为肺泡压，是指肺内的压力。在吸气时，肺内压降低，导致空气流入肺部。相反，在呼气时肺内压会增加，促进空气排出。</li>
	<li> 胸膜内压:这种压力存在于胸膜腔内，即胸膜壁层和脏层胸膜之间的空间。由于肺回缩力和胸壁扩张力之间的平衡，它通常低于大气压和肺内压，使肺保持扩张以抵住胸壁。胸膜内压的任何变化都可能导致肺塌陷或其他呼吸问题。</li>
	<li> 大气压力:大气压力是地球大气层在任何给定位置施加的压力。它是测量肺内压的基准。吸气时，肺内压下降至大气压以下，有利于空气进入，而呼气时，肺内压上升至大气压以上，将空气排出肺部。</li>
</ol>

肺通气是一个重要的生理过程，可确保肺部进行氧气与二氧化碳的交换。它指的是空气进出肺部的运动。

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

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 breathing. Inspiratory reserve volume is the extra air that can be forcefully inhaled after a normal breath, while expiratory reserve volume is the extra air that can be forcefully exhaled after a normal breath. Residual volume is the air that remains in the lungs after maximal expiration. These values are used to calculate vital capacity, which is the sum of tidal volume, inspiratory reserve volume, and expiratory reserve volume.

Normal inhalation begins when the diaphragm contracts and the external intercostal muscles contract. The diaphragm is a dome-shaped muscle that separates the thoracic cavity from the abdominal cavity, and when it flattens, the chest cavity gets larger. The external intercostal muscles lift and expand the rib cage, which also increases thoracic volume. As the chest cavity expands, intrapulmonary pressure falls and air flows from the atmosphere into the lungs.

Forced inhalation uses additional muscles when the body needs more oxygen, such as during physical exertion. The sternocleidomastoid muscle in the neck raises the sternum. The scalene muscles on either side of the neck lift the upper ribs. The pectoralis minor also helps raise the ribs and expand the chest cavity even more.

Breathing also depends on three related pressures. Intrapulmonary pressure, also called alveolar pressure, is the pressure inside the lungs. It drops during inspiration and rises during expiration. Intrapleural pressure is the pressure in the pleural cavity, between the parietal and visceral pleurae. It is usually lower than atmospheric and intrapulmonary pressure because of the balance between lung recoil and chest wall expansion, which helps keep the lungs expanded against the chest wall. If intrapleural pressure changes too much, lung collapse or other breathing problems can result. Atmospheric pressure is the pressure of the air around us, and it serves as the reference point for the pressure changes that move air in and out of the lungs.

Pulmonary Ventilation and Breathing Pressures

pulmonary-ventilation-and-breathing-pressures

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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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...

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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...

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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

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...

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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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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...

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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 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

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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

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

Explore pulmonary ventilation, lung volumes, and the pressure changes that drive inhalation, including the diaphragm, intercostal muscles, and key breathing pressures.

Pulmonary Ventilation and Breathing Pressures | 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.b

Florida Department of Education

High School

Life Science

SC.912.L.14

SC.912.L.14.44

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The final stages of digestion occur in the large intestine when the cecum receives chyme, which has little nutritional value except for the indigestible ...

Absorption of Nutrients

During digestion in the small intestine, macromolecules&#8212; carbohydrates, proteins, and fats &#8212; are broken down into their simplest forms.
These ...

Feces Formation and Defecation

After spending 3 to 10 hours in the large intestine, chyme loses a lot of water and becomes feces, the final product of digestion. Feces consist of ...

Other Disorders of Digestive System

The gastrointestinal tract of the digestive system is susceptible to various disorders.
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

Pulmonary Ventilation and Breathing Pressures

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