lOMoARcPSD|35624729 Chapter 25 Outline Human Anatomy (Salt Lake Community College) Studocu is not sponsored or endorsed by any college or university Downloaded by MichelleG (cartwheelfreak@gmail.com) lOMoARcPSD|35624729 Anatomy – Chapter 25; Respiratory system 25.1 General Organization and Functions of Respiratory System Anatomically divided into upper and lower respiratory tracts Functionally divided into conducting and respiratory function Conducting portion: Movement of air Respiratory portion: gas exchange Breathing- ventilation Inspiration- inhale Expiration: exhale Gas exchange Warming and moistening air Sound production olfacation 25.2 Upper Respiratory Tract Nasal cavity: The nose is the main conducting airway for inhaled air It is supported by paired nasal bones superiorly that form the bridge of the nose It is supported anteroinferiorly from the bridge by the fleshy, cartilaginous dorsum nasi Conchae: The superior, middle and inferior nasal conchae form the lateral wall for each cavity. These Condition the air within the nasal cavity Paranasal sinuses: Paired air spaces that make the bones lighter in weight and are named after the bones in which they reside: Frontal, Ethmoidal, Sphenoidal, Maxillary Pharynx: Region that is shared by the respiratory and digestive tracts Divided into the following regions: Nasopharynx, Oropharynx, Laryngopharynx Nasopharynx: Continuous with the nasal cavity and superior to the soft palate Lined with pseudostratified ciliated columnar epithelium Opening of the auditory tubes found in the lateral walls Posterior nasopharynx wall houses a single pharyngeal tonsil (adenoids) Oropharynx: Begins at the end of the soft palate and ends at the level of the hyoid bone Lined with nonkeratinized stratified squamous epithelium The opening of the oral cavity into the oropharynx is the fauces, defined by two pair of muscular arches on the lateral walls of the fauces The palatine tonsils are embedded in the lateral wall between the arches The lingual tonsils are at the base of the tongue Laryngopharynx: Starts inferior to hyoid bone and is continuous with the larynx and esophagus Lined with nonkeratinized stratified squamous epithelium Downloaded by MichelleG (cartwheelfreak@gmail.com) lOMoARcPSD|35624729 25.3 Lower Respiratory Tract Larynx: Also called the voice box Connects pharynx to trachea Functions: Serves as a passageway for air Prevents ingested materials form entering the respiratory tract Produces sound for speech Assists in increasing pressure in the abdominal cavity Participates in both a sneeze and cough reflex (Voice box) Vocal folds = true vocal cords Vestibular folds = false vocal cords Trachea: Referred to as the “windpipe” Anterior to the esophagus, inferior to the larynx, and superior to the main bronchi Supported by C-shaped tracheal cartilages connected by annular ligaments Cartilage Carina Bronchial tree: A highly branched system of air-conducting passages that originate from the main bronchi, progressing through narrower tubes before ending in terminal bronchioles Main bronchi: The trachea branches into left and right main bronchi at the carina Each main bronchus divides into lobar bronchi Lobar bronchi further divide into segmental bronchi Lobar bronchi Segmental bronchi … (smaller and smaller airways) Terminal bronchioles: Bronchioles branch into terminal bronchioles, which are the last portions of the conduction portion of the respiratory system ***Bronchi branch into smaller and smaller tubules that eventually reach the bronchioles, which are less than 1 mm in diameter Bronchiole walls are composed of a relatively thick layer of smooth muscle Contraction and relaxation of their smooth muscle results in bronchoconstriction and bronchodilation, respectively Respiratory bronchioles: Terminal bronchioles branch into respiratory bronchioles Respiratory bronchioles branch into alveolar ducts Alveolar ducts end with small saccular outpocketings called alveoli Downloaded by MichelleG (cartwheelfreak@gmail.com) lOMoARcPSD|35624729 The thin wall of the alveolus is the structure where respiratory gases (oxygen and carbon dioxide) diffuse between the blood and the air in the lungs Alveoli: The respiratory membrane is the diffusion barrier across which respiratory gases are exchanged between the blood and the air in the alveoli It consists of the following: Plasma membrane of the type I alveolar cell Plasma membrane of the capillary cell Fused basement membrane of both cells Alveoli Wall: The alveolar wall is formed from two types of cells: 1. Alveolar type I cells: Simple squamous epithelial cells promote rapid diffusion of gases 2. Alveolar type II cells: Almost cuboidal in shape and produce pulmonary surfactant, which decreases surface tension within the alveolus and prevents the collapse of alveoli 25.4 Lungs Pleura and pleural cavities The lungs are located in pleural cavities on the lateral sides of the thorax, separated by the mediastinum The pleural cavities and the outer surface of the lung are lined with a serous membrane called pleura Visceral pleura tightly adheres to the outside of the lung Parietal pleura lines the pleural cavity itself These two membranes are continuous with each other and the space between them is called the pleural cavity Apex: is the superior most portion of the lung The apex projects just slightly superior and posterior to the clavicle Base: Each lung is conical in shape, has a base inferiorly that rests on the diaphragm. Hilum: The mediastinal surface houses a concave region called the hilum Right lung: The right lung is divided into three lobes (superior, middle and inferior lobes) Left lung - Is slightly smaller than right lung because heart projects slightly to the left of midline The heart makes a medial surface indentation called the cardiac impression - Is divided the into two lobes (superior and inferior lobes) Blood supply The pulmonary circulation conducts blood to and from the gas exchange surfaces of the lungs The bronchial circulation is a component of the systemic circulation that delivers blood directly to and from the bronchi and bronchioles Downloaded by MichelleG (cartwheelfreak@gmail.com) lOMoARcPSD|35624729 25.5 Pulmonary Ventilation Breathing, also known as pulmonary ventilation, is the movement of air into and out of the respiratory system During inspiration, the volume of the thoracic cavity increases, intrapulmonary pressure decreases, and air flows into the lungs During expiration, the opposite occurs 25.6 Mechanics of Breathing The ventral respiratory group (VRG): controls inhalation and exhalation via phrenic and intercostal nerves to the diaphragm and intercostal muscles, respectively The dorsal respiratory group (DRG):receives information from sensory receptors in the body and relays its input to the VRG Control of respiratory system Medulla oblongata: The respiratory center in the medulla oblongata controls the rate and depth of breathing Carotid body Downloaded by MichelleG (cartwheelfreak@gmail.com)
