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Learn about the respiratory system and its various structures, including the nose, pharynx, larynx, trachea, bronchi, and lungs. Understand the process of respiration and the functions of the respiratory system.
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Respiration • The exchange of gases between the atmosphere, blood, and cells • Pulmonary Ventilation - the exchange of air between the atmosphere and lungs • External (Pulmonary) Respiration - gas exchange between the lungs and blood • Internal (Tissue) Respiration - gas exchange between the blood and cells
Functions of the Respiratory System • Provides structures and mechanisms for gas exchange • Intake of O2 • Elimination of CO2 • Helps maintains body’s pH • Sense of smell • Speech and sound production
Organs of the Respiratory System • Nose • Pharynx • Larynx • Trachea • Bronchi • Lungs
Nose • External Portion • Supporting bony framework • Cartilage - Skin • Mucous membranes • Nostrils or external nares • Internal Portion - large cavity within the skull • Connects the external nose to the pharynx through two openings (Internal Nares)
Nose • Nasal Cavity - large cavity that contains both the external and internal nose cavities • divided into the right and left sides by the NASAL SEPTUM
Functions of the Nose • Warming, moisturizing and filtering incoming air • Smell (reception of olfactory stimulus) • Resonating chamber for speech
Pharynx • Funnel-shaped tube about 13 cm long • Extends from the internal nares down to the cricoid cartilage of the larynx • Walls composed of skeletal muscle lined with a mucous membrane • Divided into three areas • Nasopharynx • Oropharynx • Laryngopharynx
Functions of the Pharynx • Passageway for food and air • Resonating chamber for speech
Larynx (Voice Box) • A short passageway that connects the pharynx with the trachea • Walls of the larynx is composed of 9 pieces if cartilage • Three single pieces of cartilage • epiglottic cartilage (Epiglottis) • thyroid cartilage (Adam’s Apple) • cricoid cartilage (attaches the Larynx to the Trachea) • Three paired pieces of cartilage • arytenoid - corniculate - cuneiform
Trachea • Tubular passageway about 12 cm long and 2.54 cm in diameter • Anterior to the esophagus • Extends from the larynx to about the 5th thoracic vertebrae • Composed of 16 - 20 C-shaped cartilage rings stacked upon one another • Hyaline cartilage rings • Covers the anterior and lateral walls
Trachea • Non-cartilaginous posterior softer portion of the trachea allows for expansion of the esophagus during swallowing • Lined with ciliated epithelium • The point where the trachea bifurcates is called the carina • About the 5th thoracic vertebrae
Bronchi • Tubes that branch off of the trachea at the carina and extend into the lungs • Left Primary Bronchus (Left Mainstem Bronchus) • Right Primary Bronchus (Right Mainstem Bronchus) • Shorter and more vertical • Swallowed objects more likely to lodge in the right primary bronchus than the left
Bronchi • Also composed of cartilaginous rings • Continue branching as they enter the lungs into a structure called the bronchial tree • Trachea -Mainstem (Primary) Bronchi - Secondary (Lobar) Bronchi - Segmental (Tertiary) Bronchi - Terminal Bronchioles - Respiratory Bronchioles - Alveolar Ducts
Bronchioles • Bronchioles are smaller air passages which branch from the bronchi. Bronchioles are small, muscular tubes with a narrow diameter. Changes in the size of the bronchioles help direct the flow of air to various parts of the lungs.
Alveolar Ducts • Alveolar ducts are enlarged chambers found at the end of the bronchioles. These very fine passageways end at the alveolar sacs and connect to the alveoli.
Alveoli • A cup shaped out pouching of epithelial tissue • Place where external respiration occurs (gas exchange between the lungs and the blood) • Lungs contain 300 - 500 million alveoli • Surface area of about 750 sq. ft. • The size of a Tennis Court
Pharynx • Funnel-shaped tube about 13 cm long • Extends from the internal nares down to the cricoid cartilage of the larynx • Walls composed of skeletal muscle lined with a mucous membrane • Divided into three areas • Nasopharynx • Oropharynx • Laryngopharynx
Structures of the Larynx • Epiglottis • Glottis • Hyoid Bone • Thyroid Cartilage • Cricoid Cartilage • True and False Vocal Cords
Epiglottis • Large leaf-shaped piece of cartilage lying on top of the larynx • The stem of the epiglottic cartilage is attached to the thyroid cartilage • Leaf portion of the cartilage is unattached and acts like a trap door covering the opening to the trachea which is called the glottis. • Dependent upon breathing or swallowing
Glottis • The opening from the pharynx to the larynx that contains the vocal cords • Vocal Cords - mucous membrane folds that extend across the glottis in two layers • upper layer or folds - false vocal folds • lower layer or folds - true vocal folds • Sounds originate from vibration of these true vocal cords
Hyoid Bone • Is located in the neck between the lower jaw and the larynx. • It does not articulate with any other bones. • It serves as the posterior attachment for the tongue and helps in swallowing.
Thyroid Cartilage • The thyroid cartilage is the largest cartilage of the larynx. • It give the larynx its characteristic triangular shape. • Nicknamed the Adam’s Apple because of its enlarged size due to the influence of testosterone.
Cricoid Cartilage • The most inferior cartilage of the larynx. • Used as a landmark to perform a tracheotomy.
True Vocal Cords • The most inferior of the horizontal folds in the larynx. • Contain elastic fiber which vibrate to create sound.
False Vocal Cords • The most superior of the folds in the larynx. • Help the glottis close during swallowing to prevent food from entering the lower respiratory passages.
Lungs • Paired - cone shaped organs that occupy most of the thoracic cavity • Separated from each other by the heart and other structures of the mediastinum • Surrounded by a double layered serous membrane called the pleural membrane
Features of the Lungs • Apex - the pointed, superior portion of the lungs. • Base – the broad, inferior surface of the lungs which rests on the diaphragm.
Pleural Membrane • Parietal Pleura - outer layer of the pleural membrane • Attached to the thoracic wall • Visceral Pleura - inner layer of the pleural membrane • Attached to the lungs themselves • Between the parietal pleura and the visceral pleura is a potential space called the pleural cavity • Contains pleural (serous) fluid (reduces friction)
Gross Anatomy of the Lungs • Extend from the diaphragm to an area about 2.54 cm above the clavicles on both sides of the thoracic cavity • Base • Apex • Hilus • Lobes
Lobes and Fissures • Each lung is divided into lobes by one or more fissures • There are three lobes in the right lung and two lobes in the left lung.
Pleural Cavity • The mediastinum divides the thoracic cavity into two pleural cavities, each of which contains one lung.
Gas Exchange • Gas exchange occurs in the alveoli due to the difference in the partial pressures of oxygen and carbon dioxide in the capillary blood and the alveoli. • Since the concentration of oxygen is greater in the alveoli, it diffuses into the capillary blood.
Since the level of carbon dioxide is higher in the capillary blood than in the alveoli, carbon dioxide diffuses out of the blood and into the alveoli.
Lung Parameters • Tidal Volume (TV) - 500 ml - volume of air moved in and out of the lungs during breathing • Vital Capacity (VC) - 4500 ml - maximum volume of air that can be exhaled after taking the deepest possible inhalation VC - TV + IRV + ERV
Physiology of Ventilation • Ventilation - the process of inhaling and exhaling air in and out of the lungs • Pulmonary Ventilation - the process by which air flows between the lungs and the external environment • Due to a change in pressure between the atmosphere and the air in the lungs