Anatomy of Respiration System-1 PDF

Malaysian Allied Health Sciences Academy Faculty of Pharmacy and Biomedical Sciences Bachelor of Pharmacy with Honours ANA 6123 Anatomy and Physiology II Anatomy of respiration system (I) Chong Ho Phin (Ph.D.) [email protected]...

Malaysian Allied Health Sciences Academy Faculty of Pharmacy and Biomedical Sciences Bachelor of Pharmacy with Honours ANA 6123 Anatomy and Physiology II Anatomy of respiration system (I) Chong Ho Phin (Ph.D.) [email protected] 1 Subtopics and learning outcomes Subtopics: Anatomy of upper respiratory tract Anatomy of lower respiratory tract Learning outcomes: Students should be able to: List the composition of upper and lower respiratory system Discuss the anatomy of the nasal cavity, sinus, pharynx, nasopharynx, oropharynx, laryngopharynx and larynx Describe the structure of trachea Describe the anatomy of bronchus and bronchioles Describe the anatomy and types of alveoli 2 Introduction The cells of the body need energy for their chemical activity that maintains homeostasis Most of this energy is derived from chemical reactions which can only take place in the presence of oxygen Loading… The main waste product of these reactions is carbon dioxide External respiration - is the exchange of gases between the atmosphere and the blood Internal respiration - is the exchange of gases between the blood and the cells of the body 3  The respiratory system The respiratory system consists of the nose, pharynx (throat), larynx (voice box), trachea (windpipe), bronchi, and lungs Structurally, the respiratory system consists of two parts: ) The upper respiratory system includes the nose, pharynx, and associated structures (2) The lower respiratory system includes the larynx, trachea, bronchi, and lungs 4 Nose and nasal cavity The nose can be divided into external and internal portions The external nose is the portion of the nose visible on the face and consists of a supporting framework of bone and hyaline cartilage covered with muscle and skin and lined by a mucous membrane Loading… The frontal bone, nasal bones, and maxillae form the bony framework of the external nose On the undersurface of the external nose are two openings called the external nares or nostrils 5 Nose and nasal cavity 6 Nose and nasal cavity The nasal cavity is the first of the respiratory organs and consists of a large irregular cavity divided into two equal passages by a septum The posterior bony part of the septum is formed by the perpendicular plate of the ethmoid bone and the vomer (the small, thin bone separating the left and right nasal cavities in humans) Anteriorly it consists of hyaline cartilage 7 Nasal cavity The space within the internal nose is called the nasal cavity The anterior portion of the nasal cavity just inside the nostrils, called the nasal vestibule, is surrounded by cartilage; the superior part of the nasal cavity is surrounded by bone A vertical partition, the nasal septum, divides the nasal cavity into right and left sides The anterior portion of the nasal septum consists primarily of hyaline cartilage; the remainder is formed by the vomer, perpendicular plate of the ethmoid, maxillae, and palatine bones 8 Nasal cavity When air enters the nostrils, it passes first through the vestibule, which is lined by skin containing coarse hairs that filter out large dust particles Three shelves formed by projections of the superior, middle, and inferior nasal conchae extend out of each lateral wall of the nasal cavity Mucous membrane lines the cavity and its shelves 9 The sinuses The paranasal sinuses are cavities in the bones of the face and the cranium which contain air They are lined with the mucous membrane, continuous with that of the nasal cavity The sinuses function in speech and also serve to lighten the skull The nasolacrimal ducts extend from the lateral walls of the nose to the conjuctival sacs of the eye. They drain tears from the eyes 10 Respiratory functions of the nose The function of the nose is to begin the process by which the air is warmed, moistened and filtered Warming: This is due to immense vascularity of the mucosa Filtering and cleaning of air : This occurs as hairs at the anterior nares trap larger particles Loading… Smaller particles such as dust and microbes settle and adhere to the mucous Mucus protects the underlying epithelium from irritation and prevents drying Synchronous beating of the cilia wafts the mucous towards the throat where it is swallowed or expectorated Humidification: This occurs as air moves over the moist mucosa and becomes saturated with water vapour 11 Olfactory function of the nose The nose is the organ of the sense of smell There are nerve endings that detect smell, located in the roof of the nose in the area of the cribriform plate of the ethmoid bone and the superior conchae These nerve endings are stimulated by chemical substances given off by odorous materials The resultant nerves to the brain where the sensation of smell is perceived 12  Pharynx The pharynx, or throat, is a funnel-shaped tube about 13 cm long that starts at the internal nares and extends to the level of the cricoid cartilage, the most inferior cartilage of the larynx (voice box) The pharynx functions as a passageway for air and food, provides a resonating chamber for speech sounds, and houses the tonsils, which participate in immunological reactions against foreign invaders The pharynx can be divided into three anatomical regions: ) Nasopharynx ) Oropharynx ) Laryngopharynx 13 Nasopharynx The superior portion of the pharynx, called the nasopharynx Lies posterior to the nasal cavity and extends to the soft palate There are five openings in its wall: two internal nares, two openings that lead into the auditory tubes (commonly known as the eustachian tubes), and the opening into the oropharynx 14 Oropharynx The intermediate portion of the pharynx, the oropharynx, lies posterior to the oral cavity and extends from the soft palate inferiorly to the level of the hyoid bone It has only one opening into it, the fauces (throat), the opening from the mouth This portion of the pharynx has both respiratory and digestive functions, serving as a common passageway for air, food, and drink Because the oropharynx is subject to abrasion by food particles, it is lined with nonkeratinized stratified squamous epithelium Two pairs of tonsils, the palatine and lingual tonsils, are found in the oropharynx 15 Laryngopharynx The inferior portion of the pharynx, the laryngopharynx, or hypopharynx, begins at the level of the hyoid bone At its inferior end it opens into the esophagus (food tube) posteriorly and the larynx (voice box) anteriorly Like the oropharynx, the laryngopharynx is both a respiratory and a digestive pathway and is lined by nonkeratinized stratified squamous epithelium 16 Larynx The larynx or “voice box” extends from the root of the tongue and the hyoid bone to the trachea It lies in front of the laryngopharynx at the level of the 3rd, 4th ,5th and 6th cervical vertebrae The larynx is composed of nine pieces of irregularly shaped cartilages attached to each other by ligaments and membranes Three occur singly (thyroid cartilage, epiglottis, and cricoid cartilage), and three occur in pairs (arytenoid, cuneiform, and corniculate cartilages). It is larger in the males, which explains the prominence of the ‘ Adam’s apple’ and the generally deeper voice 17 Larynx 18 Larynx The thyroid cartilage (Adam’s apple) consists of two fused plates of hyaline cartilage that form the anterior wall of the larynx and give it a triangular shape It is present in both males and females but is usually larger in males due to the influence of male sex hormones on its growth during puberty The epiglottis is a large, leaf shaped piece of elastic cartilage that is covered with epithelium 19 Larynx During swallowing, the pharynx and larynx rise Elevation of the pharynx widens it to receive food or drink; elevation of the larynx causes the epiglottis to move down and form a lid over the glottis, closing it off The closing of the larynx in this way during swallowing routes liquids and foods into the esophagus and keeps them out of the larynx and airways When small particles of dust, smoke, food, or liquids pass into the larynx, a cough reflex occurs, usually expelling the material 20 Larynx The paired arytenoid cartilages (ladlelike) are triangular pieces of mostly hyaline cartilage located at the posterior, superior border of the cricoid cartilage They form synovial joints with the cricoid cartilage and have a wide range of mobility The paired corniculate cartilages (shaped like a small horn), horn-shaped pieces of elastic cartilage, are located at the apex of each arytenoid cartilage The paired cuneiform cartilages (wedge-shaped), club shaped elastic cartilages anterior to the corniculate cartilages, support the vocal folds and lateral aspects of the epiglottis 21 Function of larynx Production of sound: sound has the properties of pitch, volume and resonance Speech: this occurs during expiration when the sounds produced by the vocal cords are manipulated by the tongue, cheeks and lips Protection of the lower respiratory tract: during swallowing the larynx moves upwards, occluding the opening into it from the pharynx and the hinged epiglottis closes over the larynx This ensures that food passes into the oesophagus and not into the lower respiratory passages Passageway for air: this is between the pharynx and trachea Humidifying, filtering and warming: these continue as inspired air travels through the larynx. 22 Function of larynx 23 Structure of trachea The 16 – 20 incomplete, horizontal rings of hyaline cartilage resemble the letter C, are stacked one above another, and are connected together by dense connective tissue The open part of each C-shaped cartilage ring faces posteriorly toward the esophagus and is spanned by a fibromuscular membrane The solid C-shaped cartilage rings provide a semirigid support so that the tracheal wall does not collapse inward (especially during inhalation) and obstruct the air passageway Trachealis muscle allows diameter of trachea to change during inhalation and exhalation 24 Location of the trachea in relation to the esophagus 25 Bronchi and bronchioles The bronchi are composed of the same tissue as the trachea They are lined with ciliated columnar epithelium The bronchi progressively subdivide into bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts and finally, alveoli 26 Bronchi and bronchioles At the superior border of the fifth thoracic vertebra, the trachea divides into a right primary bronchus (windpipe), which goes into the right lung, and a left primary bronchus, which goes into the left lung The right primary bronchus is more vertical, shorter, and wider than the left At the point where the trachea divides into right and left primary bronchi an internal ridge called the carina (is formed by a posterior and somewhat inferior projection of the last tracheal cartilage Carina is the most sensitive in triggering cough reflex 27 Bronchi and bronchioles On entering the lungs, the primary bronchi divide to form smaller bronchi — the secondary (lobar) bronchi, one for each lobe of the lung. (The right lung has three lobes; the left lung has two.) The secondary bronchi continue to branch, forming still smaller bronchi, called tertiary (segmental) bronchi, that divide into bronchioles Bronchioles in turn branch repeatedly, and the smallest ones branch into even smaller tubes called terminal bronchioles This extensive branching from the trachea resembles an inverted tree and is commonly referred to as the bronchial tree 28 The right bronchus The two primary bronchi are formed when the trachea divides i.e. about the level of the 5th thoracic vertebra The right bronchus: this is wider, shorter and more vertical than the left bronchus and is therefore the more likely of the two to become obstructed by an inhaled foreign body It is approximately 2.5 cm long Loading… After entering the right lung at the hilum it divides into three branches, one to each lobe, each branch then subdivides into numerous smaller branches 29 The left bronchus About 5 cm long and is narrower than the right After entering the lung at the hilum it divides into two branches, one to each lobe Each branch then subdivides into progressively smaller tubes within the lung substance 30 Bronchioles These bronchioles contain club cells, columnar non-ciliated cells interspersed among epithelial cells Club cells help in protection, produce surfactant and function as stem cell reserve 31 Respiratory bronchioles and alveoli Lobules are the blind ends of the respiratory tract distal to the terminal bronchioles, consists of respiratory bronchioles, alveolar ducts and alveoli The process of gas exchange occurs in these structures The alveoli are surrounded by a network of capillaries The exchange of gases takes place across two membranes, the alveolar and capillary membranes 32 Alveoli Around the circumference of the alveolar ducts are numerous alveoli and alveolar sacs An alveolus is a cup-shaped out pouching lined by simple squamous epithelium and supported by a thin elastic basement membrane; an alveolar sac consists of two or more alveoli that share a common opening The walls of alveoli consist of two types of alveolar epithelial cells Oxygen-rich blood Oxygen-poor blood 33 Alveoli: Types of alveolar cells Squamous epithelium Type I alveolar cells Main sites of gaseous exchange that forms a continuous lining Secrete alveolar fluid which Type II alveolar keeps surface moist cells Lowers surface tension and reduces tendency for alveoli to collapse 34 Alveoli 35 Lungs There are two lungs, one lying on each side of the midline in the thoracic cavity They are separated from each other by the heart and other structures in the mediastinum, which divides the thoracic cavity into two anatomically distinct chambers They are cone-shaped and are described as having an apex, a base, costal surface and medial surface The apex: This is rounded and rises into the root of the neck, about 25cm above the level of the middle third of the clavicle The base: This is concave and semilunar in shape and is closely associated with the thoracic surface of the diaphragm 36 Lungs: Structure Primary bronchi Secondary bronchi Tertiary bronchi Bronchioles Alveoli 37 The pleural membrane Each lung is enclosed and protected by a double-layered serous membrane called the pleural membrane The superficial layer, called the parietal pleura, lines the wall of the thoracic cavity; the deep layer, the visceral pleura, covers the lungs themselves Between the visceral and parietal pleurae is a small space, the pleural cavity, which contains a small amount of lubricating fluid secreted by the membranes This pleural fluid reduces friction between the membranes, allowing them to slide easily over one another during breathing If either layer of pleura is punctured, the underlying lung collapsed due to its inherent property of elastic recoil 38 The lungs Medially, the left lung also contains a concavity, the cardiac notch, in which the heart lies Due to the space occupied by the heart, the left lung is about 10% smaller than the right lung The lungs almost fill the thorax 39 Hilum and the mediastinum Structures which form the root of the lung enter and leave at the hilum These include the primary bronchus, the pulmonary artery supplying the lung and the two pulmonary veins draining it , the bronchial artery and veins, and the lymphatic and nerve supply The area between the lungs is the mediastinum It is occupied by the heart, great vessels, trachea, right and left bronchi, esophagus, lymph nodes, lymph vessels and nerves 40 The lobes of the lungs The right lung is divided into three distinct lobes: superior, middle and inferior The left lung is smaller as the heart is situated left of the midline It is divided into only two lobes: superior and inferior 41 Subtopics and learning outcomes Subtopics: Anatomy of upper respiratory tract Anatomy of lower respiratory tract Learning outcomes: Students should be able to: List the composition of upper and lower respiratory system Discuss the anatomy of the nasal cavity, sinus, pharynx, nasopharynx, oropharynx, laryngopharynx and larynx Describe the structure of trachea Describe the anatomy of bronchus and bronchioles Describe the anatomy and types of alveoli 42 Thank you! Have a great day! Questions? 43