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Boundless Anatomy and Physiology
Physiology Textbooks Boundless Anatomy and Physiology
Physiology Textbooks
Physiology

Chapter 21

Respiratory System

Book Version 29
By Boundless
Boundless Anatomy and Physiology
Physiology
by Boundless
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Section 1
Overview of the Respiratory System
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The Reason for Breathing

Breathing allows for the delivery oxygen to internal tissues and cells where it is needed, and allows for the removal of CO2.

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Functional Anatomy of the Respiratory System

The respiratory system include lungs, airways and respiratory muscles. Ventilation is the rate at which gas enters or leaves the lung.

Section 2
Conducting Zone
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Nose and Paranasal Sinuses

The shape of the nose is determined by the ethmoid bone and the nasal septum.

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Pharynx

The human pharynx is part of the digestive system and also the respiratory system.

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Larynx

The larynx is an organ in the neck involved in breathing, sound production, and protecting the trachea against food aspiration.

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Structures Used in Voice Production

Voices produce sounds through a steady flow of air through the larynx, which causes vibrations and creates fluctuations in air pressure.

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Trachea

The trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air.

Section 3
Respiratory Zone
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Bronchi and Subdivisions

A bronchus is a passage of airway in the respiratory tract that conducts air into the lungs and divides into terminal bronchioles.

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Alveoli

Alveoli are hollow cavities in the lung that perform gas exchange with the blood.

Section 4
The Lungs and Pleurae
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Lungs

The lungs are an essential organ which is necessary for the exchange of oxygen and carbon dioxide from the body.

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Lobes, Fissures, and Lobules

The lungs are located on either side of the heart and are separated by fissures into lobes, three in the right and two lobes in the left.

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Blood Supply to the Lungs

Pulmonary circulation transports oxygen-depleted blood away from the heart to the lungs and returns oxygenated blood back to the heart.

Section 5
Mechanics of Breathing
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Pressure Changes During Pulmonary Ventilation

Ventilation is the rate at which gas enters or leaves the lung.

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Inspiration

Inhalation is the flow of air into an organism which is generated due to pressure difference between the atmosphere and alveolus.

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Expiration

Exhalation (or expiration) is the flow of the respiratory current out of the organism.

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Breathing Patterns

Breathing is an autonomic process that moves air in and out of the lungs.

Section 6
Factors Affecting Pulmonary Ventilation
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Factors Affecting Pulmonary Ventilation: Surface Tension of Alveolar Fluid

The surface tension of alveolar fluid is regulated by pulmonary surfactant, allowing efficient respiration.

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Factors Affecting Pulmonary Ventilation: Compliance of the Lungs

Lung compliance refers to the magnitude of change in lung volume as a result of the change in pulmonary pressure.

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Factors Affecting Pulmonary Ventilation: Airway Resistance

Airway resistance refers to resistance in the respiratory tract to airflow.

Section 7
Nonrespiratory Lung Functions
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Lung Capacity and Volume

Lung volumes and capacities refer to phases of the respiratory cycle; lung volumes are directly measured while capacities are inferred.

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Nonrespiratory Air Movements

The lungs have a number of metabolic functions in addition to their functions in gas exchange.

Section 8
Gas Laws
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Dalton's Law of Partial Pressure

Dalton's law of partial pressures states that the pressure of a mixture of gases is the sum of the pressures of the individual components.

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Henry's Law

Henry's law states that the amount of a gas that dissolves in a liquid is directly proportional to the partial pressure of that gas.

Section 9
Gas Exchange
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External Respiration

Respiration is the transport of oxygen to the cells within tissues and the transport of carbon dioxide in the opposite direction.

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Internal Respiration

Cellular respiration is the metabolic process by which an organism obtains energy through the reaction of oxygen with glucose.

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Oxygen Transport

Hemoglobin is the primary transporter of oxygen with an oxygen binding capacity between 1.36 and 1.37 ml O2 per gram Hgb.

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Carbon Dioxide Transport

CO2 is carried in blood in three different ways: dissolved in plasma, bound to hemoglobin, or as a biocarbonate ion.

Section 10
Respiration Control
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Neural Mechanisms (Respiratory Center)

The medulla and the pons are involved in the regulation of the ventilatory pattern of respiration.

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Neural Mechanisms (Cortex)

The cerebral cortex of the brain controls voluntary respiration.

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Chemoreceptor Regulation of Breathing

Chemoreceptors detect the levels of carbon dioxide in the blood by monitoring the concentrations of hydrogen ions in the blood.

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Proprioceptor Regulation of Breathing

The Hering–Breuer inflation reflex prevents overinflation of the lungs.

Section 11
Respiratory Adjustments
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Adjustments During Exercise

Aerobic and anaerobic exercise work to increase the mechanical efficiency of the heart.

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Adjustments at High Altitude

The human body can adapt to high altitude through immediate and long-term acclimatization processes.

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Respiratory System
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