Anatomy and Physiology PDF

Anatomy of pulmonary system The pulmonary system consists of: - thorax - conducting airways, - respiratory airways - pulmonary blood and lymph supply. Anatomy of pulmonary system The primary functions of the pulmonary system are: - ventilation - respiration Anatomy of pulmonary system - Venti...

Anatomy of pulmonary system The pulmonary system consists of: - thorax - conducting airways, - respiratory airways - pulmonary blood and lymph supply. Anatomy of pulmonary system The primary functions of the pulmonary system are: - ventilation - respiration Anatomy of pulmonary system - Ventilation: is the movement of air in and out of the lungs. - Respiration :is the process of gas exchange by means of movement of oxygen from the atmosphere into the bloodstream and movement of carbon dioxide from the bloodstream into the atmosphere. Anatomy of pulmonary system - An applicable knowledge of anatomy and physiology is imperative in caring for the patient with pulmonary dysfunction. Anatomy of pulmonary system THORAX The thorax contains the major organs of respiration. It consists of : - thoracic cage - lungs - pleura - muscles of ventilation. * these structures form the ventilatory pump, which performs the work of breathing. Anatomy of pulmonary system  Thoracic Cage: The thoracic cage is a cone-shaped structure that is rigid but flexible. It must be somewhat rigid to protect the underlying structures. - it must be flexible to accommodate inhalation and exhalation. The cage consists of 12 thoracic vertebrae. - Posteriorly, each rib is attached to its own vertebra. - anteriorly, attachment varies. - The first seven pairs of ribs are attached directly to the sternum. Anatomy of pulmonary system - The 8th,9th, and 10th pairs are attached by cartilage to the ribs above. - The 11th and 12th ribs have no anterior attachment. - They sometimes are referred to as floating ribs. - The second rib is attached to the sternum at the angle of Louis, which is the raised ridge that can be felt just below the suprasternal notch. Anatomy of pulmonary system Anatomy of pulmonary system Anatomy of pulmonary system  Lungs: The lungs are cone-shaped organs that have a total volume of - The superior portion is known as the apex. - The inferior portion is known as the base. - The apical portion of each lung rises a few centimeters above the clavicle. Anatomy of pulmonary system Lobes and segments: - The right lung, which is larger and heavier than the left, is divided into upper, middle, and lower lobes. - The left lung is divided into only an upper and a lower lobe. Anatomy of pulmonary system - The horizontal fissure divides the right upper lobe from the right middle lobe. - The oblique fissure divides the right upper and middle lobes from the right lower lobe and the left upper lobe from the left lower lobe. - The lobes are divided into 18 segments. - Each of which has its own bronchus branching. - Ten segments are located in the right lung and eight in the left lung. Anatomy of pulmonary system Anatomy of pulmonary system Anatomy of pulmonary system Mediastinum is the area between the two lungs. - the mediastinum, contains: - heart - great vessels - lymphatics - esophagus. Anatomy of pulmonary system - The lungs contain the following: 1- Lobes 2- Segments 3- Mediastinum Anatomy of pulmonary system  Pleura: The pleura is a thin membrane that lines the outside of the lungs and the inside of the chest wall. - The visceral pleura adheres to the lungs, extending onto the hilar bronchi and into the major fissures. Anatomy of pulmonary system - The parietal pleura lines the inner surface of the chest wall and mediastinum. - The two pleural surfaces are separated by an airtight space, which contains a thin layer of lubricating fluid. Anatomy of pulmonary system - Pleural fluid allows the visceral and parietal pleural membranes to glide against each other during inhalation and exhalation. Anatomy of pulmonary system Intrapleural pressure: - The pleural space has a pressure within it called the intrapleural pressure, which differs from the intrapulmonary (pressure within the lungs) and atmospheric pressures. Anatomy of pulmonary system - Under normal conditions, intrapleural pressure is less than intrapulmonary pressure and less than atmospheric pressure, with a normal range of 4 to −10 cm H2O during exhalation and inhalation. - deep inhalation can generate intrapleural pressures of 12 to −18 cm H2O. Anatomy of pulmonary system  Muscles of Ventilation: - The muscles of ventilation are governed by the regulatory activity of the central nervous system, which sends messages to the muscles to stimulate contraction and relaxation. - Muscles that increase the size of the chest are called muscles of inhalation; those that decrease the size of the chest are called muscles of exhalation. Anatomy of pulmonary system Anatomy of pulmonary system Inhalation - The main muscle of inhalation is the diaphragm. - The diaphragm is a dome-shaped, fibromuscular septum that separates the thoracic and abdominal cavities. Anatomy of pulmonary system - During normal, quiet breathing, the diaphragm does approximately 80% of the work of breathing. - On inhalation, the diaphragm contracts and flattens, pushes down on the viscera, and displaces the abdomen outward. Anatomy of pulmonary system - The action of the diaphragm is governed by the medulla, which sends its impulses through the phrenic nerve. - The phrenic nerve arises from the cervical plexus through the fourth cervical nerve, with secondary contributions by the third and fifth cervical nerves. Anatomy of pulmonary system - most of the work of inhalation, trauma involving levels C3 to C5 causes ventilatory dysfunction. - Other muscles of inhalation include those that lift the rib cage. - The most important of these are the external intercostal muscles, which elevate the ribs and expand the chest cage outward. - The scalene, anterior serratus, an sternocleidomastoid muscles also participate to elevate the first two ribs and sternum. Anatomy of pulmonary system Exhalation - Exhalation in the healthy lung is a passive event requiring very little energy. Exhalation occurs when the diaphragm relaxes and moves back up toward the lungs. Anatomy of pulmonary system - During exercise, however, exhalation becomes a more active event, requiring some participation of the accessory muscles of ventilation. Anatomy of pulmonary system Accessory Muscles - The accessory muscles of ventilation usually are considered to be those that enhance chest expansion during exercise but that are not active during normal, quiet breathing. - These muscles include: *scalene *sternocleidomastoid * chest *back muscles (trapezius ,pectoralis major). Anatomy of pulmonary system CONDUCTING AIRWAY Upper airway All structures above glottis Lower airway All structures below glottis Anatomy of pulmonary system The purposes of the conducting airways are: 1-warm and humidify the inhaled air. 2- act as a protective mechanism that prevents the entrance of foreign matter into the gas exchange areas. Anatomy of pulmonary system Anatomy of pulmonary system  Upper Airway - Consist of: 1-Two openings (mouth,nose) 2- Nasopharynx Air passes through from nose Superior part of the pharynx 3- Oropharynx Air passes through from mouth Extends to level of epiglottis 4- Uvula Where nasopharynx ends, oropharynx begins Anatomy of pulmonary system 5- Laryngopharynx (hypopharynx) Extends from tip of epiglottis to glottis and esophagus. Opens into larynx, which lies in anterior neck. Anatomy of pulmonary system Anatomy of pulmonary system 6- Larynx: - Consists of outer casing of nine cartilages Connect to each other by muscles, ligaments Six of nine are paired Three are unpaired Anatomy of pulmonary system oUnpaired cartilages Thyroid cartilage Largest, most superior of cartilages Also know as Adam's apple Cricoid cartilage Most inferior cartilage Only complete cartilage ring in larynx Epiglottis Anatomy of pulmonary system - The epiglottis is located in the upper airways. It protects the lower airways by closing the opening to the trachea during swallowing so that food passes into the esophagus and not the trachea. Anatomy of pulmonary system Anatomy of pulmonary system - The epiglottis is a thin, leaf-shaped, elastic cartilage that is located directly posterior to the root of the tongue and attached to the thyroid cartilage. Anatomy of pulmonary system - It opens widely during inhalation, permitting air to pass through the trachea into the lower airways. Anatomy of pulmonary system oPaired cartilages Stacked in two pillars between cricoid cartilage and thyroid cartilage Arytenoid cartilages Corniculate cartilages Cuneiform cartilages Anatomy of pulmonary system Anatomy of pulmonary system Vocal cords Regulate flow of air to and from lungs for production of voice sounds Endotracheal tube passed through during ET intubation Pyriform sinus Recess located on either side of larynx Foreign materials can become lodged there Anatomy of pulmonary system  Lower Airway - Consist of: Trachea: The trachea is a hollow tube approximately 11 cm (4.5 inches) long and 2.5 cm (1 inch) in diameter - the cricoid cartilage and ends at the bifurcation (major carina) from which the two main stem bronchi arise. - The carina is positioned approximately at the level of the aortic arch, the fifth thoracic vertebra, or just below the level of the angle of Louis. Anatomy of pulmonary system - The trachea consists of smooth muscle supported anteriorly by 16 to 20 C-shaped, cartilaginous rings. They prevent tracheal collapse during bronchoconstriction and strong coughing. - The posterior wall of the trachea lies contiguous with the anterior wall of the esophagus. Anatomy of pulmonary system Bronchial Tree: The two main stem bronchi are structurally different. - left bronchus: is slightly narrower than the right, and because of its position above the heart, the left bronchus angles directly toward the left lung at approximately 45 to 55 degrees from the midline. - right bronchus: is wider and angles at 20 to 30 degrees from the midline. Anatomy of pulmonary system - Because of this angulation and the forces of gravity, the most common site of aspiration of foreign objects is through the right main stem bronchus into the lower lobe of the right lung. Anatomy of pulmonary system Anatomy of pulmonary system oBronchi: each branching of the tracheobronchial tree produces a new generation of tubes. - first generation (primary bronchus): includes main stem bronchi. - second generation (secondary bronchus):includes five lobar bronchi. third generation(Tertiary bronchus) includes the 18 segmental bronchi. Anatomy of pulmonary system - The fourth through approximately the ninth generations are referred to as the small bronchi, beginning with the subsegmental bronchi. - In these bronchi, diameters decrease; however, because the number of bronchi increases with each generation. Anatomy of pulmonary system o Bronchioles: The final subdivision of the conducting airways is the bronchioles. - These tubes have a diameter less than 1 mm and have no connective tissue and cartilage within their walls. - Smallest airways without alveoli. Anatomy of pulmonary system RESPIRATORY AIRWAYS - The respiratory airways consist of the respiratory bronchioles and the alveoli. respiratory bronchioles: it is form the transition zone of the lungs, acting gas exchange units. Anatomy of pulmonary system Anatomy of pulmonary system Alveoli: Each respiratory bronchiole gives rise to several alveolar ducts, which terminate in clusters of 10 to 16 alveoli - Each terminal respiratory unit contains approximately 100 alveolar ducts and 2000 alveoli. Anatomy of pulmonary system - The alveolus is the primary site of gas exchange and the end point in the respiratory tract. - Approximately 300 million alveoli are in the two lungs. - The alveoli are composed of several types of cells: 1- type I alveolar epithelial cells 2-typeII alveolar epithelial cells 3-alveolar macrophages(defence system). Anatomy of pulmonary system o Type I Alveolar Epithelial Cells: - Type I alveolar epithelial cells comprise approximately 90% of the total alveolar surface within the lungs - They are - play a major role in the maintenance of the gas-blood barrier and gas exchange. - Type I cells are extremely susceptible to injury and become inflamed when exposed to inhaled toxins. Anatomy of pulmonary system o Type II Alveolar Epithelial Cells: - Type II alveolar epithelial cells occur in much greater numbers than type I cells, but because of their minute size, they comprise a smaller portion of the total alveolar wall. - The most important function of the type II cells is their ability to produce, store, and secrete pulmonary surfactant. Anatomy of pulmonary system - Surfactant: Surfactant is a phospholipid composed of fatty acids. pulmonary surfactant functions to lower surface tension of the alveoli, increases lung compliance, and eases the work of breathing. When pulmonary disease disrupts the normal synthesis and storage of surfactant, the lungs become less compliant, and the work of breathing increases. Severe loss of surfactant results in alveolar instability and collapse and impairment of gas exchange. Anatomy of pulmonary system - When pulmonary disease disrupts the normal synthesis and storage of surfactant, the lungs become less compliant, and the work of breathing increases. - Severe loss of surfactant results in alveolar instability , collapse and impairment of gas exchange. Anatomy of pulmonary system oalveolar macrophages: Alveolar macrophages are monocytes that originate in the bone marrow and are released into the bloodstream. - On entering the pulmonary capillary circulation, they move through the capillary membrane wall into the interstitial space and through to the alveoli. Anatomy of pulmonary system - In the alveoli, the monocytes transform into macrophages. They move from alveolus to alveolus through the pores of Kohn, keeping the alveoli clean and sterile through phagocytosis and microbial killing activity, which includes the secretion of hydrogen peroxide, lysozyme, and other substances that kill microorganisms. Anatomy of pulmonary system PULMONARY BLOOD AND LYMPH SUPPLY  Pulmonary Circulation - The pulmonary circulatory system begins at the pulmonary artery, which receives venous blood from the right side of the heart. - The pulmonary artery then divides into left and right branches and continues to branch until it forms the capillaries that surround the alveoli. Anatomy of pulmonary system - After gas exchange takes place, the blood is returned to the left side of the heart through the pulmonary veins. Alveolar capillary membrane: - The alveolar-capillary membrane is less than 0.5 micron thick and is composed of several layers of cells: the alveolar epithelium, the alveolar basement membrane, the interstitial space. - the capillary basement membrane, and the capillary endothelium Anatomy of pulmonary system - Blood entering pulmonary capillaries is systemic venous blood that has been circulated to lungs via pulmonary arteries Pco2 is relatively high in this blood, Po2 is low Alveoli have greater concentration of O2 than blood entering pulmonary capillaries O2 molecules diffuse from alveoli into blood CO2 moves from blood, where it is more concentrated, into alveoli, where it is less concentrated Anatomy of pulmonary system Differences in Po2 and PCo2 on two sides of membrane result in diffusion O2 moves into blood and CO2 into alveoli Capillary blood Po2 level rises Capillary blood Pco2 level falls Diffusion stops when alveolar and capillary partial pressures equalize Anatomy of pulmonary system Oxygen and carbon dioxide traverse easily across these layers, which present no barrier to diffusion because the membrane is very thin. Anatomy of pulmonary system Anatomy of pulmonary system - The bronchial arteries that perfuse structures in the left side of the thorax branch off the aorta, and those that perfuse the right-sided structures branch from the intercostal,subclavian, or internal mammary artery. Anatomy of pulmonary system Physiological shunting: - The left atrium normally contains pure oxygenated blood, with a hemoglobin saturation level of 100%. Anatomy of pulmonary system  Lymphatic Circulation - The lungs are more richly supplied with lymphatic tissue than any other organ, perhaps because of their constant exposure to the external environment. - The lymphatic vessels parallel much of the pulmonary vasculature and the tracheobronchial tree to the level of the terminal and respiratory bronchioles. Anatomy of pulmonary system - Lymphatic vessels also are located within the connective tissue of lung parenchyma and within the pleural membranes. These vessels eventually drain into the primary lymph nodes located at the hila of the lungs. Anatomy of pulmonary system - The lymphatic system is responsible for: removing foreign particles and cell debris from the lungs. producing antibody- and cell-mediated immune responses. responsible for removing fluid from the lungs. keeping the alveoli clear. Physiology of pulmonary system Ventilation - Air moves into and out of the lungs because of the difference between intrapulmonary pressure (pressure inside the lungs) and atmospheric pressure. - The movement of air into the lungs is known as inhalation , and the movement of air out of the lungs is known as exhalation Physiology of pulmonary system  Respiratory phase: 1- External respiration Transfer (diffusion) of O2 and CO2 between inspired air and pulmonary capillaries 2- Internal respiration Transfer (diffusion) of O2 and CO2 between capillary red blood cells and tissue cells Physiology of pulmonary system  Pressure Changes and Ventilation: Pressure gradient needed for gas to flow into lungs Produced by differences between atmospheric pressure, intrapulmonic pressure, and intrathoracic pressure (intrapleural pressure) Physiology of pulmonary system Atmospheric pressure Pressure of gas around us Varies with differences in altitude At sea level, is 760 mmHg Physiology of pulmonary system Intrapulmonary pressure Pressure of gas in alveoli. Depending on size of thorax, varies a little above and below 760 mmHg. Depends on whether it is measured during inspiration or expiration. Physiology of pulmonary system Intrathoracic pressure Pressure in pleural space Normally less than atmospheric pressure (usually 751 to 754 mmHg. May exceed atmospheric pressure during coughing. Physiology of pulmonary system Inspiration - The muscles of ventilation contract, the thorax and lungs expand and intrapulmonary pressure falls. - When the pressure falls below atmospheric pressure, air enters the lungs, and inhalation occurs. Physiology of pulmonary system Expiration - At the end of inhalation, the muscles of ventilation relax, the thorax contracts and the lungs are compressed, and intrapulmonary pressure rises. - When the pressure rises above atmospheric pressure, air exits the lungs, and exhalation occurs. Physiology of pulmonary system Physiology of pulmonary system Physiology of pulmonary system Physiology of pulmonary system Physiology of pulmonary system Work of Breathing - The work of breathing is the amount of work that must be performed to overcome the elastic and resistive properties of the lungs. Physiology of pulmonary system - The elastic properties are determined by lung recoil, chest wall recoil, and the surface tension of the alveoli. - The resistive properties are determined by airway resistance. Physiology of pulmonary system - During normal, quiet ventilation, only 1% to 2% of basal oxygen consumption is required by the pulmonary system. - During heavy exercise, the amount of energy required by the pulmonary system can become progressively greater. Physiology of pulmonary system - The work of breathing can be a factor that limits exercise in the patient with pulmonary disease. - Pathologic conditions that increase the work of breathing. Physiology of pulmonary system - pulmonary diseases that decrease lung compliance : atelectasis, pulmonary edema. - pulmonary diseases that decrease chest wall compliance: kyphoscoliosis. - pulmonary diseases that increase airway resistance : bronchitis, asthma. - pulmonary diseases that decrease lung recoil : emphysema. Physiology of pulmonary system - pulmonary diseases that decrease secreation of pulmonary surfactant: smoking inhalation - The factors that increase the work of breathing: - Loss of pulmonary surfactant - Decrease in lung compliance - Increase in airway resistance - Decrease in lung recoil - Decrease in chest wall compliance Physiology of pulmonary system - Increased work of brathing Usually obvious from use of accessory muscles during labored breathing: Scalenes Sternocleidomastoid Posterior neck and back muscles Abdominal muscles Physiology of pulmonary system Physiology of pulmonary system  Pulmonary Volumes and Capacities Pulmonary volumes: - Tidal volume (VT): is the amount of air inhaled and exhaled with each breath. (500 to 600 mL) - Inspiratory reserve volume (IRV): Gas amount forcefully inhaled after inspiration of normal tidal volume. (2000 to 3000 mL) - Expiratory reserve volume (ERV): Gas amount forcefully exhaled after expiration of normal tidal volume. (1200 mL) Physiology of pulmonary system - Residual volume (RV): Gas remaining in respiratory system after forced expiration. (1000 to 1200 mL) Physiology of pulmonary system Pulmonary capacities : It is sum of two or more pulmonary volumes - Inspiratory capacity (IC): is the sum of the tidal volume and the inspiratory reserve volume. - Functional residual capacity (FRC) : is the sum of the expiratory reserve volume and the residual volume. - Vital capacity (VC): is the sum of the inspiratory reserve volume, the tidal volume, and the expiratory reserve volume. Physiology of pulmonary system - Total lung capacity (TLC): is the sum of all four volumes and represents the maximal amount of air that can be inhaled or Sum of vital capacity + residual volume Physiology of pulmonary system Physiology of pulmonary system Physiology of pulmonary system Respiration - Respiration refers to the movement of oxygen and carbon dioxide. - Gas exchange that takes place at the lung level through the alveolar- capillary membrane is referred to as external respiration. - The diffusion of gases in and out of the cells at the tissue level is referred to as internal respiration. Physiology of pulmonary system  Diffusion: - Oxygen and carbon dioxide move throughout the body by diffusion. - Diffusion moves molecules from an area of high concentration to an area of low concentration. - The difference in the concentrations of the gases is referred to as the driving pressure. Physiology of pulmonary system - The greater the driving pressure of the gas through the membrane, the greater the rate of diffusion Within the lungs. - diffusion occurs because of the difference in the driving pressure between the pulmonary capillaries and the alveoli. Physiology of pulmonary system - Oxygen is in high concentration within the alveoli and exerts a higher driving pressure as compared with the pulmonary capillaries, therefore, oxygen moves by diffusion from the alveoli into the pulmonary capillaries. Physiology of pulmonary system - Carbon dioxide is in higher concentration and has a higher driving pressure within the pulmonary capillaries compared with the alveoli; therefore, carbon dioxide diffuses out of the capillaries into the alveoli. Physiology of pulmonary system - The driving pressure of oxygen is lower at higher altitudes because the effects of gravity on the gases are lessened, and it is higher when supplemental oxygen is administered. Physiology of pulmonary system - several other factors affect the rate of diffusion: 1- thickness of the alveolar-capillary membrane or surface area of the membrane: An increase in the thickness of the alveolar-capillary membrane (e.g., pulmonary edema, fibrosis) or a decrease in the surface area of the membrane (e.g., pneumonectomy , lobectomy , pulmonary embolus, emphysema)decreases the rate of diffusion. Physiology of pulmonary system 2- diffusion coefficient of the gas: - The diffusion coefficient of each gas is determined by its solubility. - The higher the diffusion coefficient, the faster the gas diffuses. Carbon dioxide has a much higher diffusion coefficient than oxygen, and carbon dioxide diffuses 20 times more rapidly than does oxygen. Physiology of pulmonary system Physiology of pulmonary system GAS TRANSPORT - Gas transport refers to the movement of oxygen and carbon dioxide to and from the tissue cells. The transportation vehicle is the bloodstream, which is moved by the pumping action of the heart (cardiac output). - At the tissue level, oxygen and carbon dioxide move into and out of the cell by diffusion. Physiology of pulmonary system - Oxygen diffuses into the cell because of the pressure gradient that exists between oxygen in the capillary and oxygen in the cell - Carbon dioxide diffuses into the capillary because of the pressure gradient that exists between carbon dioxide in the cell and carbon dioxide in the capillary. Physiology of pulmonary system Physiology of pulmonary system Oxygen Content - Oxygen is transported to the tissues by the blood in two ways: 1- It is dissolved in plasma (Pao2) 2- bound to hemoglobin molecules (oxygen saturation [Sao2]). - Most of the oxygen is transported by hemoglobin, with the portion of oxygen dissolved in plasma equal to approximately 3% of the total oxygen within the blood. Physiology of pulmonary system - The pressure exerted by the oxygen dissolved in plasma is important because this oxygen diffuses across the capillary membrane into the cells first and serves as the vehicle for the unloading of the oxygen from the hemoglobin molecule. Physiology of pulmonary system - As dissolved oxygen leaves the plasma and diffuses into the cells, the molecules of oxygen move off the hemoglobin molecule, dissolve into the plasma, and diffuse into the cells. - For this process to begin, a pressure gradient must exist between the oxygen level in the capillary and the oxygen level in the cell. Physiology of pulmonary system Oxygen Content Formula - The amount of oxygen in the arterial blood can be calculated using the arterial oxygen content (Cao2) formula. - The amount of oxygen in the venous blood can be calculated using the venous oxygen content (Cvo2) formula