Anatomy & Physiology Of Respiratory Tract 1 PDF

1. ANATOMY & PHYSIOLOGY OF RESPIRATORY TRACT 1 Prof. Dr. Nadia Yassin  GRADE DISTRIBUTION - Final exam 40% - Midterm exam 30% - Quizzes 20% - Student activities (class work & essay) 10% 2  Competency Domain 1: F...

1. ANATOMY & PHYSIOLOGY OF RESPIRATORY TRACT 1 Prof. Dr. Nadia Yassin  GRADE DISTRIBUTION - Final exam 40% - Midterm exam 30% - Quizzes 20% - Student activities (class work & essay) 10% 2  Competency Domain 1: Fundamental Knowledge 1-1Competency Key Elements 1-1-1 Integrate knowledge of the principles of basic, medical and clinical sciences 1-1-2 Identify the anatomical structure of certain systems of the human body including the anatomy of respiratory system, renal system, endocrine system, reproductive system and gastrointestinal tract. 1-1-3 Demonstrate the physiological function of certain systems of the human body including the respiratory system, the renal system, the endocrine system, the reproductive system and the gastrointestinal tract as well as the regulation of various body processes in these systems. Emphasis will also be placed on some diseases caused by certain pathophysiological changes in different organs (e.g.: atelectasis, respiratory distress syndrome, diabetes……) 1-1-4 Utilize the proper medical terms and being aware with medical procedures related to pharmacy practice Domain 2: Professional and Ethical Practice 2-2 Competency Key Elements 2-2-1 Apply some medical tools, techniques and diagnostic tests 2-2-2 Analyze normal and abnormal diagnostic tests in some clinical disorders 3 Domain 3: Pharmaceutical Care 3-1 Competency Key Elements 3-1-1 Relate specific anatomical structures of different body organs with their related functions (eg. Anatomy of respiratory passages and their correlated functions, anatomy of renal tubules and the specific function of each….) 3-1-2 Interpret different mechanisms of action related to different body systems. 3-1-3 Apply the principle of body functions in health and diseases, such as diabetes mellitus, chronic hypertension, acromegaly, Cushing syndrome Domain 4: Personal Practice. 4-1 Competency Key Elements 4-1-1 Work effectively in a team. 4-1-2 Demonstrate critical thinking 4-2 Competency Key Elements 4-2-1 Communicate clearly by verbal & written means 4-2-2 Implement writing & presentation skills 4-3 Competency Key Elements 4-3-1 Practice independent learning needed for continuous professional development 4  Competency Identify the main function of the respiratory system. Describe the anatomical structure of the respiratory system. Correlate the special structure of the respiratory system with its function. Enumerate the different types of cells lining the respiratory passages. List the different layers of the respiratory membrane. Interpret the mechanics of respiration. Define the intraalveolar and the intrapleural pressures and describe the variation of their values with inspiration and expiration. Discuss the causes of negativity of the intrapleural pressure. 5  Chief Functions of Respiratory System Supply of O2 and removal of CO2 Regulation of pH of blood Major Respiratory Events: A. External Respiration: Pulmonary ventilation: Exchange of air between atmosphere & lungs Diffusion of gases between lungs & blood Transport of gases in blood Diffusion of gases between blood and tissues B. Internal Respiration: Utilization of O2 & production of CO2 by cells (esp. mitochondria). 6 ANATOMY & FUNCTION OF RESPIRATORY SYSTEM Air enters through nose & mouth Pharynx Larynx Trachea 7  ANATOMY & FUNCTION OF RESPIRATORY SYSTEM (cont.) In the thorax, the trachea divides into 2 main bronchi branch into smaller bronchi bronchioles (> 20 generations of branching into progressively smaller tubes) terminal bronchioles & respiratory bronchioles. In respiratory bronchioles alveoli begin to appear. Number of alveoli increases in alveolar ducts. Airways end in grape-like clusters; alveolar sacs, which consist of alveoli. 8  ANATOMY & FUNCTION OF RESPIRATORY SYSTEM (cont.) The respiratory system is divided into: 1. Conducting Zone : - Extends from trachea to terminal bronchioles. - Its main function is to conduct air towards alveoli. 2. Respiratory Zone: - Extends from respiratory bronchioles to alveoli. - Its main function is to permit gas exchange with blood. Rings of Cartilage: Trachea & bronchi contain cartilage rings produce cylindrical shape to these structures. prevent their collapse during respiration. N.B. Intrapulmonary bronchi & bronchioles contain no cartilage rings. Smooth Muscles: Bronchi & bronchioles are surrounded by smooth muscles. Their contraction & relaxation can alter the radius of airways. During exercise & stress bronchioles open & air flow to lungs . 9  ANATOMY & FUNCTION OF RESP. SYSTEM Epithelial Lining of Respiratory Passages:  The epithelial surfaces of airways until the end of respiratory bronchioles contain: - Ciliated epithelium - Mucus-secreting goblet cells  Alveoli are mainly formed of flat epithelial cells. Alveoli contain 2 types of cells: 1. Type I alveolar cells: flat epithelial cells. One layer of these cells forms the walls of alveoli. 2. Type II alveolar cells: cuboidal cells interspersed between type I cells. They secrete surfactant. Dust cells: They are alveolar macrophages. Humidification & Warming of Air: Beneath the epithelium of the conducting zone there is a rich network of capillaries that releases moisture & heat:  Moisture protects lungs from drying out  Heat protects lungs from cold temperatures By the time that air reaches the alveoli it is nearly saturated with 10 water & warmed to body temp.  ANATOMY & FUNCTION OF RESPIRATORY SYSTEM (cont.) Respiratory Membrane: - Alveoli are tiny hollow sacs, which open into the airways. - There are ~ 300 million alveoli in both lungs. - They have a surface area of 60-80 m2. - They are surrounded by capillaries. - The respiratory membrane is composed of: 1. Fluid lining alveoli 2. One layer of epithelial cells 3. Basement membrane of epithelial cells 4. Interstitial space 5. Basement membrane of endothelial cells 6. One layer of endothelial cells - It allows diffusion of gases through it. - The respiratory membrane is ~ 0.2 m thick. 11 RESPIRATORY MEMBRANE 12  PULMONARY VENTILATION MECHANICS OF RESPIRATION The respiratory cycle is composed of  inspiration In adults there are ~ 12 breaths/min.  expiration during quiet breathing = eupnia Inflow & outflow of air between atmosphere & lungs (pulmonary ventilation) occurs by:  expansion of chest  contraction wall Lungs follow changes in chest size because they are connected to chest wall via the pleura. Pleura is composed of 2 layers:  Visceral pleura: covering the lung  Parietal pleura: lining the chest wall There is one pleural sac for each lung. Between the 2 layers of the pleura there is a watery fluid with strong cohesive forces that prevent lungs & chest wall to be pulled apart. The 2 layers are only able to slide against each other. 13  MECHANICS OF RESPIRATION INSPIRATION It is an active process. It is brought about by an  in length & diameter of chest wall by contraction of inspiratory ms.: 1. Diaphragm: - Dome-shaped ms. - Inserted in lower ribs - Nerve supply: phrenic nerve - Contraction: it becomes flat  length of thoracic cavity - It is responsible for 75% of  in intrathoracic volume. 2. External intercostal muscles: - At rest, ribs are inclined downwards - Nerve supply: external intercostal nerves - Contraction: elevates ribs & pushes sternum forwards  antero-posterior & transverse diameters of chest. With forced inspiration, accessory inspiratory ms. contract. 14 They contract at rest in chronic respiratory diseases.  MECHANICS OF RESPIRATION EXPIRATION It is a passive process. During inspiration, the elastic structures of the lungs are stretched. When contraction of inspiratory muscles stops:  Diaphragm relaxes becomes dome-shaped  Elastic structures of lungs retract to their initial shape = elastic recoil  Air is forced out of lungs With heavy breathing, elastic forces are insufficient to cause rapid expiration, so that extra forces are required: contraction of expiratory muscles. In disease states, as bronchial asthma (constriction of airways) &  lung elasticity (emphysema, pulmonary fibrosis) expiratory muscles must also work at rest. 15 MECHANICS OF RESPIRATION INSPIRATION & EXPIRATION 16  RESPIRATORY PRESSURES 1. Atmospheric Pressure: It is 760 mmHg at sea level. To compare respiratory pressures to it, it is considered to be zero = “zero reference pressure”. 2. Intraalveolar Pressure (PA) = Intrapulmonary Pr.: Definiton: It is the pressure inside alveoli. Boyle’s Law: It describes the relation between pressure & vol. It states: For a given volume of a gas in a container, the pressure is inversely proportional to the volume of the container. P  1/Vol.  volume  volume P P If vol. of container  press. exerted by gas  & vice versa. 17  PULMONARY PRESSURES DURING RESPIRATORY CYCLE 2. Alveolar Pressure (PA) = Intrapulmonary Pr. (cont): Normal Values: - At rest: With airways open & no air flowing in or out: zero cm H2O (atm.) - With inspiration: Expansion of CW*: -1 cm H2O  vol. of lung subatm. PA a pressure gra- dient bet. alveoli & atm. air flows into alveoli pressure at end of inspiration: 0 cm H2O - With expiration: Recoil of CW: +1 cm H2O  vol. of lungs  PA a pressure gradient between alveoli & atmosphere air flows out pressure at end of expiration: 0 cm H2O * CW = chest wall 18 ALVEOLAR PRESSURE 19  PULMONARY PRESSURES DURING RESPIRATORY CYCLE (cont.) 3. Intrapleural Pressure (PPL): Definiton: It is the pressure inside the narrow space between the two layers of pleura. Under normal conditions, the PPL is always -ve due to continuous - tendency of lung to recoil inwards - tendency of chest wall to expand outwards. Causes of recoil tendency of lung & expansion tendency of chest wall: 1. Elastic properties of lungs & CW: - Relaxation volume of lung is 1 L - Relaxation volume of chest wall (CW) is 5 L - At end of expiration vol. of both is 2.3 L  Lungs are stretched tend to recoil CW is compressed tends to expand 2. Surface tension of fluid lining alveoli: At air-fluid interface: there are strong intramolecular attraction forces between surface molecules of fluid lining alveoli, which try to  the 20 surface area tendency to collapse lungs.  PULMONARY PRESSURES DURING RESPIRATORY CYCLE (cont.) 3. Intrapleural Pressure (PPL): (cont.) Normal Values: - At the end of normal expiration: There is minimal lung expansion & minimal recoil tendency  pressure is -3 cm H2O - At the end of normal inspiration: There is more lung expansion more recoil tendency  pressure is -6 cm H2O Functions of PPL: 1. Keeps alveoli open 2. Helps venous return N.B. In lung diseases with destruction of elastic fibers (as emphysema), recoil tendency of lungs is  PPL is less negative. 21