Pulmonary System Anatomy & Physiology II 2019 PDF

Pulmonary System Anatomy & Physiology II BIOL2220 Version 08.1 Pulmonary System Nasal Cavity Anatomy - Introduction The first portion of the respiratory tract is made up o...

Pulmonary System Anatomy & Physiology II BIOL2220 Version 08.1 Pulmonary System Nasal Cavity Anatomy - Introduction The first portion of the respiratory tract is made up of the nose and an open inner chamber called the nasal cavity (1). The nose serves as a vent for air exchange. Two openings called anterior nares (3) (or nostrils; exterior nares) allow air to enter the nose and pass into the nasal cavity After circulating over the nasal cavity structures, air passes into the pharynx through two posterior nares (2) (or choanae; internal nares). 2 Pulmonary System Nasal Cavity-Turbinates Anatomy - Introduction There are three (3) turbinates on each side of the nasal cavity, and all are covered by a thick layer of mucous membrane Air “swirls” across the mucosa when breathing in. It is warmed, humidified, and cleaned. 3 Pulmonary System Sinuses Anatomy - Introduction Two frontal sinuses (1) are just above the orbits, and several small ethmoid sinuses (2) are between the orbits. There are two large maxillary sinuses (3), and and two sphenoid sinuses (4). -Mucus produced in the sinuses normally drains out of small apertures (or ostia) and adds to the mucus in the nasal cavity. -The open sinuses also help lighten the skull and resonate the voice sounds. 4 Pulmonary System Pharynx Anatomy - Introduction The pharynx is a fibromuscular tube that conducts air from the nasal cavity to the larynx. It is divided into three anatomical regions: Nasopharynx (1), Oropharynx (2), and Laryngopharynx (3) 5 Pulmonary System Eustachian Tube Anatomy - Introduction Along the lateral walls of the nasopharynx are the openings to the Eustachian tubes (pharyngotympanic tubes). Each tube connects the nasopharynx with the middle ear The tubes are used to equalize the pressure on both sides of the eardrum (or tympanic membrane), making it easier for the eardrum to vibrate in response to sound waves. 6 Pulmonary System Larynx Anatomy - Introduction There are nine (9) laryngeal cartilages, three paired and three single. Together, they form a supportive skeletal framework for the vocal cords. 7 Pulmonary System Trachea Anatomy - Introduction The trachea (or windpipe) is a vertical tube that runs through the neck and chest, just anterior to the esophagus. The trachea functions to conduct air between the larynx and the mainstem (primary) bronchi. Embedded in the wall of the trachea are 16 to 20 tracheal C-rings made of hyaline cartilage. 8 Pulmonary System Bronchi Anatomy - Introduction Near the sternal angle, the trachea bifurcates (or splits) at the Carina, into the right and left primary bronchi. Each bronchus runs freely for a few centimeters, then enters its respective lung. Air flows in and out of each lung through the primary bronchi. After entering a lung, each primary bronchus divides into secondary bronchi. The secondary bronchi are also known as lobar bronchi because each one directly conducts air to and from one of the lung’s five lobes. Within a lobe, tertiary bronchi branch from the secondary bronchi. The tertiary bronchi give rise to bronchioles (shown on slide 12). Carina 9 Pulmonary System Lung Lobes & Bronchopulmonary Segments Anatomy - Introduction Each of the five lung lobes is divided by connective tissue walls (= septa) into anatomical compartments called bronchopulmonary segments. Typically, there are 10 segments in both the right & left lung. Each segment functions independently and is supplied by its own tertiary bronchus (or segmental bronchus) artery, vein, lymph vessels, and autonomic nerves. Thus, if one segment is infected or damaged, others in the same lobe may not be affected. Basically, each bronchopulmonary segment is an anatomical and functional subdivision of a lobe. 10 Pulmonary System Secondary Pulmonary Lobules Anatomy - Introduction Walls of connective tissue (or septa) partition the bronchopulmonary segments into many polygonal-shaped secondary pulmonary lobules (or pulmonary lobules). The secondary pulmonary lobules measure approximately 1-3 centimeters in diameter and contain 3-5 terminal bronchioles (the smallest conducting tubules) and many respiratory bronchioles, alveolar ducts, and alveoli (where gases are exchanged with surrounding blood vessels). 11 Pulmonary System Terminus of the Airway Anatomy - Introduction The respiratory bronchioles (1) inside a secondary pulmonary lobule gives rise to two or more alveolar ducts (3). Protruding from the walls of the alveolar ducts and respiratory bronchioles are many bubble shaped alveoli (2), each measuring about 0.2 – 0.5 mm in diameter. At the distal end of an alveolar duct, the alveoli are arranged into grape-like clusters called alveolar sacs (4). The alveoli share a common opening to the alveolar duct. All alveoli are covered by a capillary sphere to facilitate gas exchange with the blood. 12  Pulmonary System Pleura Anatomy - Introduction Each lung is enveloped in its own double-membrane pleural sac. The inner membrane adheres to the outer surface of the lung and is called the visceral pleura. The outer membrane is called the parietal pleura and is an extension of the visceral pleura, which doubles back on itself at the hilum (hilus) and runs along the surfaces of the rib cage, diaphragm, and mediastinum. The parietal pleura secretes a thin layer of pleural fluid into the pleural cavity. An open space does not normally exist in the pleural cavity because the pleural fluid loosely attaches the two membranes. During breathing movements, this seal allows the two membranes to slide past one another. The pleurae also form a barrier that helps protect the lungs from infections that can occur elsewhere in the thoracic cavity. Important Pressure Terms Involving Pleura: Intra-Pulmonary Pressure – Inside Of Lungs/Inside the Visceral Pleura Intra-Pleural Pressure – Outside the Lungs/Inside Of Pleural Cavity. Pressure here is always less than Intra-Pulmonary, regardless of the phase of breathing Trans-Pulmonary Pressure – Pressure difference between Intra-Pulmonary and Intra-Pleural 13 Pulmonary System Tracking Important Tissues Anatomy - Introduction Nose (Nasal Cavity) Anterior: Stratified Squamous (nonkeratinized) Epithelium Posterior: Pseudo-Stratified Ciliated Columnar Epithelium NasoPharynx Pseudo-Stratified Ciliated Columnar Epithelium OroPharynx Stratified Squamous (nonkeratinized) Epithelium. LaryngoPharynx Stratified Squamous (nonkeratinized) Epithelium Pseudo-Stratified Ciliated Columnar Epithelium Submucosal Mucous Glands Trachea C-Shaped Cartilage “Rings”. Smooth Muscle. Columnar Epithelium Bronchi Submucosal Mucous Glands O-Shaped Cartilage Rings. Smooth Muscle. Bronchioles Changes as they get smaller from Columnar to Cuboidal to Simple Squamous. Smooth Muscle disappears as they get smaller Mainly Simple Squamous Epithelium. Note Type I Pneumocytes (Squamous), Type II Pneumocytes Alveoli (modified Cuboidal) & Macrophages 14 Pulmonary System Radiographic Anatomy of the Chest Anatomy - Overview Note the following: The darkness of the lung fields (filled with air) The “cloudy” appearance of each hilum (blood & lymph vessels) The margins around the lung, and the base & apex 15  Radiographic Anatomy of the Lungs Pulmonary System Right lung—3 lobes Anatomy - Overview 16  Radiographic Anatomy of the Lungs Pulmonary System Left lung—slightly smaller than right (Why?), 2 lobes Anatomy - Overview 17 Pulmonary System Important Microanatomy Anatomy Trachea At Higher Magnification, Showing Pseudo-Stratified Ciliated Columnar Epithelium Lining The Lumen. A Wide Blood Vessel Lies In The Lamina Propria Below. Hyaline Cartilage Is At The Bottom Of The Picture. Lung: B= Respiratory Bronchiole With Alveolus (A) In Its Wall. Most Of The Wall Of The Bronchiole Has A Definite Line Of Dark Along It, Signifying A Cuboidal Or Columnar Epithelium (Simple, Rather Than Pseudostratified). D&C= Alveolar Duct. Its Wall Consists Almost Entirely Of Alveoli, Which Have Only A Simple Squamous Lining, Too Flat To Be Visible Here. E= Alveoli (The Smallest Respiratory Units) F= Blood Vessel (Likely a Branch Of Pulmonary Artery/Vein) 18 Pulmonary System Gas Exchange Tissue Anatomy - Overview Respiratory Segment: Respiratory Bronchioles : – Give Off Alveoli. – Give Off Alveolar Ducts. Alveolar Ducts: – Give Off Alveoli Only. Alveolar Sacs: – Spaces Surrounded By Clusters Of Alveoli. Important Cells of the Alveoli: Type I Pneumocytes (Epithelial Cells). Type II Pneumocytes (Surfactant Cells). – Secrete Surfactant – Maintain Openings. – BIG, At Corners Of Alveoli. Macrophages: – Within The Alveolar Space. 19 Pulmonary System Blood Flow Through Lungs Anatomy - Overview Pulmonary Arteries Carries Deoxygenated Blood From The Right Ventricle Of Heart To Lungs. Pulmonary Capillaries Site For Gas Exchange. Pulmonary Veins Carries Oxygenated Blood From The Lungs To Left Atrium Of Heart. Bronchial Arteries Main Blood Supply To The Tissues Of The Lung. Enter Through Hilum Of Each Lung. 20 Pulmonary System Important Muscles Of Ventilation Anatomy - Overview Internal Intercostals Muscles Of External Internal Transversus Rectus Expiration Abdominal Abdominal Abdominis Abdominis Oblique Oblique Parasternal External Intercostals Sternocleidomastoid Intercostals Muscles Of Diaphragm Inspiration Scalenes 21 Pulmonary System Functions Physiology Processes: Functional Zones: 1. Pulmonary Ventilation: 1. Conducting Air In/Out Of Lungs. Trachea. AKA Breathing. Bronchi. Large, Small & Terminal 2. External Respiration: Bronchioles. Pulmonary Capillaries Blood – Air Gas Exchange 3. Transport Of Respiratory Gases: Review info from CV system. RBC & Hb 4. Internal Respiration: 2. Respiratory Systemic Capillaries. Respiratory Bronchioles. Blood – Tissue Gas Alveolar Ducts. Exchange. Alveoli. Key Operations: 1.Remove CO2 – Metabolic Waste: Hypercapnic Drive 2.Remove H+ - Acid/Base Balance: Acidotic Drive 3.Provide O2 – Metabolic Requirement For Aerobic Respiration: Hypoxemic Drive 22 Pulmonary System Respiratory Control Mechanisms Physiology General: You don't have to think about breathing because your body's Nervous System controls it, as it does many other functions in your body. If you try to hold your breath, your body will override your action and force you to let out that breath and start breathing again. The Respiratory Centers that control your rate of breathing are in the Pons Or Medulla. The nerve cells that live within these centers automatically send signals to skeletal muscles such as the Diaphragm And Intercostal Muscles, which then contract and relax at regular intervals. However, the activity of the respiratory centers can be influenced by several factors: Oxygen: Specialized nerve cells within the aorta and carotid arteries called Peripheral Chemoreceptors monitor the Oxygen Concentration Of The Blood and feed back on the respiratory centers via CN IX and X. If the oxygen concentration in the blood decreases, they tell the respiratory centers to increase the rate and depth of breathing. Carbon Dioxide: Peripheral Chemoreceptors also monitor the Carbon Dioxide Concentration In The Blood. In addition, a Central Chemoreceptor In The Medulla monitors the Carbon Dioxide Concentration In The Cerebrospinal Fluid (CSF) that surrounds the brain and spinal cord; carbon dioxide diffuses easily into the CSF from the blood. If the carbon dioxide concentration gets too high, then both types of chemoreceptors signal the respiratory centers to increase the rate and depth of breathing. The increased rate of breathing returns the carbon dioxide concentration to normal and the breathing rate then slows down. Hydrogen ion (pH): The Peripheral And Central Chemoreceptors are also sensitive to the pH Of The Blood And CSF. If the H+ Concentration increases (that is, if the fluid becomes more acidic), then the chemoreceptors tell the respiratory centers to speed up. H+ concentration is heavily influenced by the Carbon Dioxide Concentration in the blood and CSF. 23 Pulmonary System Respiratory Control Mechanisms Physiology Stretch: Stretch Receptors in the lungs and chest wall monitor the Amount Of Stretch in these organs. If the lungs become over-inflated (stretch too much), they signal the respiratory centers to exhale and inhibit inspiration. This mechanism (Herring-Breuer) prevents damage to the lungs that would be caused by over-inflation. Signals From Higher Brain Centers: Nerve cells in the Hypothalamus And Cortex also influence the activity of the respiratory centers. During pain or strong emotions, the Hypothalamus will Tell The Respiratory Centers to speed up. Nerve centers in the Cortex can Voluntarily Tell The Respiratory Center to speed up, slow down or even stop (holding your breath). Their influence, however, can be overridden by chemical factors (oxygen, carbon dioxide, pH). Chemical Irritants: Nerve Cells In The Airways sense the presence of Unwanted Substances In The Airways such as pollen, dust, noxious fumes, water, or cigarette smoke. These cells then signal the respiratory centers to contract the respiratory muscles, causing you to sneeze or cough. Coughing and sneezing cause air to be rapidly and violently exhaled from the lungs and airways, removing the offending substance. Summary: Of these factors, the Strongest Influence Is The Carbon Dioxide Concentration In Your Blood And CSF, then the Hydrogen ion concentration, followed by the oxygen concentration. 24 Pulmonary System Respiratory Control Physiology “Ondine’s Conscious Cortex Curse” Contol Pain, Strong Hypothalamus Emotion, Etc. Respiratory Centers CO2 In CSF Central Pons pH Of CSF Chemoreceptors Medulla Oblongata Regulated Volume Pattern Generator Reflex Expulsion Regulated Rate Inflation Reflex Hering-Breuer Cough, Sneeze, Etc. CO2 In Blood pH Of Blood Peripheral Chemoreceptors Foreign O2 In Blood Substance Recognition Circuit Priority Stretch 1. CO2 Receptors 2. H+/pH 25 3. O2 Pulmonary System Respiratory Control Physiology Nucleus Pons Parabrachialis Pneumotaxic Breathing Rate (-) Apneustic Stop Breathing In Exertive Is Linked To Exercise – Need Both Forced Inspiration & Expiration Modulation Nucleus Nucleus Tractus Solitarus Ambiguous Medulla Oblongata Expiration & Ventral Dorsal Inspiration Inspiration (Exertive) (Normal) Only Nucleus Respiratory Centers RetroAmbiguous Vagus Peripheral Central Chemoreceptors Chemoreceptors CO2, H+ & Glossopharyngeal CO2 & H+ O2 (Aorta/Carotid) (Direct Connect) 26 Pulmonary System Respiratory Control: Adapting to the Environment Physiology Now that some breathing control mechanisms have been detailed, let’s look at what happens to your breathing under different circumstances. For example, what happens to your breathing rate during exercise? It increases, right? But why? Here’s the flow chart: Medullary Breathing Exercise Metabolic Demand Kreb’s Cycle CO2 Rate In blood Activation This is an example of hypercapnic drive. Here’s another. What happens to your breathing rate when you are at altitude? It increases, right? But why? Here’s the flow chart: O2 in Diffusion of O2 O2 Medullary Breathing Air at Into the Body in blood Activation Rate Altitude This is an example of hypoxemic drive. 27 Pulmonary System Basic Principles Of Breathing Physiology 3 Basic Steps 1.Ventilation Is Mechanical – Air In/ Air Out. 2.Lungs Inflate/Deflate Due To Pressure Changes. 1. Ventilation Of Lungs. 3.The Pressure Changes Occur Because of Volume Changes (See Boyle’s Law) Inspiration Air Pressure > Intra- Pulmonary Pressure. 2. Gas Exchange: Expiration Air Pressure < Intra- Pulmonary Pressure. Pressure Changes As A Function Of External Respiration Lung Volume. Lung Volume Changes As A Function (Air To Capillaries In Of Thoracic Volume. This is driven by skeletal muscles, the Lungs). most important being the diaphragm Internal Respiration 1.Concentration Of O2 In Air Is Higher Than O2 Of (Capillaries To Tissues Blood. (Diffusion in) 2.Concentration Of CO2 In Blood Is Higher Than Air. Of Body). (Diffusion out) 1.Concentration Of O2 In Blood Is Higher Than 3. O2 Utilization (Cellular O2 Of Tissues. (Diffusion in) 2.Concentration Of CO2 In Tissues Is Higher 28 Respiration) Than Blood. (Diffusion out) Pulmonary System How Volume Affects Pressure: Boyle’s Law Physiology In the 1700's Robert Boyle investigated the relationship between the volume of a dry ideal gas and its pressure. Since there are four variables that can be altered in a gas sample, in order to investigate how one variable will affect another, all other variables must be held constant or fixed. Boyle fixed the amount of gas and its temperature during his investigation. He found that when he manipulated the pressure that the volume responded in the opposite direction. For example, when Boyle increased the pressure on a gas sample the volume would decrease. Boyle’s Law P1xV1 = P2xV2 29 Pulmonary System How Volume Affects Pressure: Boyle’s Law Physiology A life dependent example of Boyles Law is the action of the ventilatory muscles on the movement of air into and out of the lungs. When we inhale the chest expands allowing the lungs an increased volume. This decreases the pressure inside the lungs so that the pressure is less than the outer pressure. In other words, the Atmospheric Pressure would now be greater than the Intrapulmonary Pressure. This results in forcing air into the lungs. When we exhale the chest compresses and decreases the volume of the lungs. This increases the pressure inside the lungs (Intrapulmonary Pressure) above the pressure on the outside of the lungs (Atmospheric Pressure) so that gases are forced out of the lungs. Boyle’s Law Relationship of Variables éVèêP êVèéP 30 Pulmonary System Inspiration/Expiration Physiology Inspiration Expiration Quiet Inspiration Results From Contraction Of The Diaphragm & External 1 Diaphragm Contracts & Flattens 1 Diaphragm Relaxes & Rises Intercostal Muscles. Quiet Expiration Is Passive w/ Muscles Relaxing & 2 Diaphragm Moves Down 2 Thoracic Volume Decreases Thoracic Cage Recoils. 3 Thoracic Volume Increase 3 Lungs Recoil – Lung Volume Forced Inspiration Includes Decreases The Scalenes, Pectoralis Minor & Sternocleido- mastoid Muscles. 4 4 Lungs Stretched Down – Volume Up Lung Pressure Increases Forced Expiration Involves Contraction Of Internal Intercostals & Abdominal 5 5 Muscles. Lung Pressure Decreases Air Flows Out Of Lungs Via Passive Transport Until Pressure Is Equalized 6 Air Rushes In To Lungs Until Pressure Is Equalized 31 Pulmonary System Physiology The Law of LaPlace: Properties That Affect Lung Function Pressure In Alveoli Is Directly Proportional To Surface Tension And Inversely Proportional To Its Radius. Surface Tension: The Cohesion of Water On Its’ Surface Pressure In Smaller Alveoli Would Be Greater If Surface Tension Is Held Constant=Which It Would Be Unless We Add Something To It. Surfactant (Made By Type II Pneumocytes) Lowers Surface Tension By Intervening In The Attraction Between Water Molecules. In Other Words, Surfactant Reduces Cohesion. As The Radius Of Alveoli Decreases The Surfactant’s Ability To Lower Surface Tension Increases. We do this by Concentrating Surfactant in the Smaller Spaces of Smaller Alveoli. Law Of Laplace Relationship of Variables Law Of Laplace éRèêP êRèéP éTèéP P = (2 x T)/R êTèêP Pulmonary System Properties That Affect Physiology Lung Function If we apply Laplace's law to each of the fluid-lined alveoli, then we find a remarkable discrepancy in the pressure gradients across the walls of the two alveoli, alveolus B (lower) and alveolus A (higher). This surely means that air will move from the small to the big alveolus, as the pressure in the smaller alveolus is higher! The small alveolus will get smaller, the large one will get larger, and so on until the small alveolus collapses completely! Why does this not happen in real life? The answer is that, because we can’t change the radius of the alveoli, we have to change the surface tension so this it is equal in each alveolus. We do this by lowering the surface tension with surfactant! Surfactant, composed of mainly dipalmitoyl phosphatidyl choline, with a touch of phosphatidyl glycerol thrown in, not only lowers the surface tension of the alveolar fluid, but it lowers the surface tension more A as the alveolar radius decreases! B Pulmonary System The Classic Spirometer Volumes Physiology 6 5 Normal Tidal Volume = ½ Liter IRV 4 FVC TLC Tidal 3 Volume (TV) 2 ERV FRC 1 Residual Volume (RV) 0 TV = Tidal Volume IRV = Inspiratory Reserve Volume RV = Residual Volume FRC = Functional Residual Capacity ERV = Expiratory Reserve Volume FVC = Forced Vital Capacity TLC = Total Lung Capacity 34 Pulmonary System Modern Spirometry Physiology Blowing forcefully into a Spirometer tube provides a quick, easy measure of both FEV1 and FEV6 (FVC). The Spirometer measures two important numbers; FEV1 and forced vital capacity FEV6 (FVC). These numbers are simple expressions of complex processes ( just like blood pressure measures a complex process). The numbers obtained for FEV1 (air flow) and FEV6 (FVC) (air volume) by a spirometer are important to help diagnose lung & airway diseases and to monitor the course of these diseases and their response to treatment. During testing, patients are asked to hold the tube of a spirometer in their mouth, inhale as much air as possible, then exhale forcefully into the spirometer for six seconds or more. It is now known that the forced expiratory volume in six seconds (FEV6) is an excellent surrogate for FVC. 35 Pulmonary System Laws that Influence Diffusion Physiology Dalton’s Law…… Total Pressure = Sum Of All Partial Pressures PDry Air = PN2 + PO2 + PCO2 = 760mmHg Air ~78% N2 21% O2