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Chapter_26__Respiratory_System
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- ATLS Pretest + Modules
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- ATLS Pretest + Modules
Chapter_26__Respiratory_System
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Chapter 26: Respiratory System called anatomic dead space (VD).The air filling this The pulmonary artery receivesspace with every breath is not available for gas deoxygenated blood from the righ
Upper Respiratory Tract The upper respiratory tract exchange of the heart and delivers it to pulm
includes the nose, mouth, pharynx, epiglottis, larynx, and Surfactant: The lungs are a collection of 300 million capillaries that are directly connec
trachea. Air enters into the respiratory tract through the alveoli, each 0.3 mm in diameter. Surfactant is a lipoprotein alveoli. O2-CO2 exchange occurs a
nose. The nose is made of bone and cartilage and is that lowers the surface tension in the alveoli. It reduces the point. Pulmonary veins returns oxy
divided into two nares by the nasal septum. The inside of amount of pressure needed to inflate the alveoli and makes blood to L atrium → L ventricle →
the nose is shaped into three passages by projections them less likely to collapse. systemic circulation
called turbinates. The turbinates increase the surface area ➔ Atelectasis : collapsed, airless alveoli (due to ➔ Bronchial circulation: starts with the
of the nasal mucosa. inadequate surfactant) arteries. The bronchial circulation provi
● Pharynx is divided into 3 parts ➔ Produced by Type II alveolar cells = small & to the bronchi and other pulmonary tiss
● Epiglottis: small flap located behind the tongue that cuboidal, cover only about 5% of the alveolar Deoxygenated blood returns from the b
closes over the larynx during swallowing surface area, but are as numerous as Type I cells circulation through the azygos vein into
● Vocal cords : located in the Larynx Blood Supply: The lungs have two different types of superior vena cava
● The trachea bifurcates into the right and left circulation: pulmonary and bronchial. Chest Wall
mainstem bronchi at a point called the carina ➔ Pulmonary circulation: provides the lungs ● Paritel & Visceral Pleura
● The carina is located at the level of the with blood that participates in gas exchange. ● Intrapleural space
manubriosternal junction, also called the angle of ● Diaphragm
Louis Physiology of Respiration
● The carina is highly sensitive, and touching it during
suctioning causes vigorous coughing\ Ventilation: involves inspiration and expiration
in and out of the lungs because intrathoracic pr
Lower Respiratory Tract The lower respiratory tract consists changes in relation to pressure at the airway op
of the bronchi, bronchioles, alveolar ducts, and alveoli. With Contraction of the diaphragm and intercostal an
the exception of the right and left mainstem bronchi, all muscles increases chest dimensions. thereby d
lower airway structures are located inside the lungs. Te intrathoracic pressure. Gas flows from an area
right lung is divided into three lobes (upper, middle, and pressure (atmospheric) to one of lower pressur
lower) and the left lung into two lobes (upper and lower) (intrathoracic)
● Once air passes the carina, it is in the lower ➔ In contrast to inspiration, expiration is p
respiratory tract. Elastic recoil is the tendency for the lun
● The mainstem bronchi, pulmonary vessels, and after being stretched or expanded
nerves enter the lungs through a slit called the hilus. ➔ Exacerbations of asthma or chronic ob
● The right mainstem bronchus is shorter, wider, and pulmonary disease (COPD) cause exp
straighter than the left mainstem bronchus. For this become an active, labored process
reason, aspiration is more likely to occur in the right
lung than in the left lung. Compliance: (aka distensibility) is a measure
● The trachea and bronchi act as a pathway to conduct of expansion of the lungs. Tis is a product of th
gases to the alveoli. The trachea plus the bronchi are the lungs and the elastic recoil of the chest wal
, compliance is decreased, the lungs are more difficult to concentration. An increase in the H+ concentration
inflate. Compliance is increased when there is destruction (acidosis) causes the medulla to increase the
of alveolar walls and loss of tissue elasticity, as in COPD, respiratory rate and tidal volume (VT)
Diffusion: Oxygen and carbon dioxide move back and
forth across the alveolar-capillary membrane by diffusion.
The overall direction of movement is from the area of
higher concentration to the area of lower concentration.
➔ PaO2 (mmHg) = Partial pressure of O2 in arterial
blood. Represents the amount of O2 dissolved in
the plasma
➔ SaO2 (%) = amount of oxygen bound to
hemoglobin in comparison with the amount of
oxygen the hemoglobin can carry
● Mechanical Receptors: Mechanical receptors
Arterial Blood Gases (juxtacapillary and irritant) are located in the lungs,
Two methods are used to assess the efficiency of gas upper airways, chest wall, and diaphragm. They are
transfer in the lung and tissue oxygenation: analysis of stimulated by a variety of physiologic factors, such as
arterial blood gases (ABGs) and pulse oximetry irritants, muscle stretching, and alveolar wall
distortion. Signals from the stretch receptors aid in the
➔ ABG = determine oxygenation status and acid control of respiration. As the lungs inflate, pulmonary
base balance stretch receptors activate the inspiratory center to
inhibit further lung expansion. Tis is termed the
Mixed Venous Blood gases Hering-Breuer refex, and it prevents overdistention of
For the patient with a normal or near-normal cardiac status, the lungs
an assessment of PaO2 or SaO2 is usually sufficient to
determine the level of oxygenation.
Oximetry
Arterial oxygen saturation can be monitored noninvasively
and continuously using a pulse oximetry probe on the
finger, toe, ear, or bridge of the nose
Control of Respiration
● Chemoreceptors: A chemoreceptor is a receptor that
responds to a change in the chemical composition
(PaCO2 and pH) of the fluid around it. Central
chemoreceptors are located in the medulla and
respond to changes in the hydrogen ion (H+ )
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