Respiratory System & Pulmonary Function PDF

RESPIRATORY SYSTEM PULMONARY FUNCTION (Faculty of Dentistry and Health Science) Prof. Dr. Lamia Pınar Okan Üniversitesi Tıp Fakültesi Fizyoloji Anabilim Dalı The main functions of respiration are to provide oxygen to the tissues by inspiration (inhalation) and remove carbon dioxide from the body by...

RESPIRATORY SYSTEM PULMONARY FUNCTION (Faculty of Dentistry and Health Science) Prof. Dr. Lamia Pınar Okan Üniversitesi Tıp Fakültesi Fizyoloji Anabilim Dalı The main functions of respiration are to provide oxygen to the tissues by inspiration (inhalation) and remove carbon dioxide from the body by expiration (exhalation) Gas exchange O2 CO2 3 Respiratory Physiology O2 External respiration: - transport of O2 from atmosphere  cell’s mitochondria - transport of CO2: CO2 lung from the cell’s mitochondria  atmosphere Internal respiration: heart Cell metabolism by using Oxygen and releasing Carbon dioxide +Water + ATP O2 CO2 tissues (Oxidative Phosphorylation) 4 The function of the respiratory system (in detail) Exchange of oxygen (O₂) and carbon dioxide (CO₂) between the air and the cells of the body. During inspiration, fresh air (O₂) is brought into the lungs through the respiratory passage (respiratory pathway) CO₂, as a waste product of tissue metabolism, is carried to the lungs and is expelled from the respiratory passage CO₂ and O₂ are carried by the capillaries to the alveoli of the lungs and exchanged in the alveoli Other functions of the respiratory system The lung also plays a role in: Provide a defensive mechanism to viruses, bacteria, and foreign particles. A primary barrier between the outside world and the inside of the body. The lung is also a metabolic organ that synthesizes and metabolizes numerous compounds. Circuitry of the Cardiovascular system The heart has right and left atriums and right and left ventricles. All the vessels coming from the body and lungs flow into the atriums, All the vessels carry the blood to the body, and lungs emerge from the ventricles As a rule; All the vessels that return to the heart are called veins. All the vessels that eject the blood from the heart to the body are called arteries. Veins and Arteries of the Cardio-Respiratory system Vena Cavae sup and inf carry venous blood (high amount of CO₂) from the organs, and flows into the right atrium then, the blood flows into the right ventricle (through the tricuspid valve). From the right ventricle, the dirty blood (having high CO₂) is pumped to the lungs by way of the pulmonary artery. Left and Right Sides of the Heart Oxygenated blood (having high O₂) in the lungs turns to the left atrium by way of the pulmonary veins. Then flows into the left ventricle. Left ventricle pumps blood to all organs of the body except the lungs. Left heart and the systemic arteries, capillaries, and veins constitute systemic circulation. The rate at which blood is pumped from either ventricle is called the cardiac output (CO). The blood flowing from the left atrium to the left ventricle passes through the mitral valve (bicuspid valve). When the left ventricle contracts (systole), blood is ejected into the aorta via the aortic semilunar valve and goes to the organs. When the right ventricle contracts (systole) blood is ejected through the pulmonary semilunar valve and goes to the lungs The pumping amount of blood from both ventricles are same and is called cardiac output (CO) CO= stroke volume x heart rate in 1 minute Stroke volume, is the volume of blood pumped from each ventricle per beat. CO= 70 ml x 70-80beats/per min CO (at resting)= 4900-5000ml= 5 L In the capillary beds of the lungs Oxygen (O₂) is transferred to the blood from the alveolus, and Carbondioxide (CO₂) is removed from the blood and transferred to the alveoli then, it is expelled out of the lungs. Thus, the blood leaving the lungs has more O₂ (clear blood) and less CO₂ The RESPIRATORY SYSTEM Respiratory Passage (Respiratory Airway) Structure and Function of Airways (Respiratory Passage) Respiratory Airways Nose, Larynx Trachea Right and left primary bronchus Bronchioles Terminal bronchioles FUNCTION: Filtration, Conduction, Moistening, and Heating of air Mucociliary cells trap the foreign particles and throw them out of the respiratory passage RESPIRATION (Gas Exchange) begins in the: Respiratory bronchioles, Ductus alveolaris and Alveoli (plural of alveolus) There are also macrophages in the alveoli to scavenge (remove) the bacteria and viruses The right primary bronchus is wider and vertical. For this reason, foreign bodies escaping into the respiratory passage are mostly stuck in this bronchus. alveoli Bronchial tree Ankara, Oct. 2006 Blood vessels 18 Capillaries of Pulmonary arteries carry dirty blood (deoxygenated) from de Right ventricle, Capillaries of Pulmonary veins carry the clean (oxygenated) blood from the alveoli. Respiratory mechanics depends on Boyle Marriot Law means that the pressure of a given quantity of gas varies inversely with its volume at a constant temperature. It means that, if the volume of the gas filled in an area increases, the pressure of the gas decreases, or if the volume of the gas decreases, the pressure of the gas increases. Lung Membranes (Pleuras) There are 2 membranes around the lungs. These are called Pleura. The inner Visceral pleura surrounds the lungs, The outer Parietal pleura surrounds the thoracic cavity. The 2 pleura are connected. Between the two membranes, there is negative pressure as they attract each other in opposite directions. Also, there is a very little amount of liquid that facilitates the sliding of the membranes over each other. In the resting state between the inspiration and expiration this negative pressure is about (- 4mmHg or, even -5mmHg). You can refer to it as water pressure (-4 or -5 H2O). During inspiration, intrapleural pressure becomes - 6mmHg or - 7mmHg If one or both of these membranes are punctured, air enters the intrapleural space, and the positive pressure puts pressure on the lung, deflating it. This is called Pneumothorax. Mechanics of breathing: Pleura intrapleural pressure 24 Mechanics of breathing: Inspiration begins with the contraction of the diaphragm and external intercostal muscles. This increases the negative pressure in the chest wall and causes the lungs to be expanded. Expiration occurs passively by elastic recoil (deflation) of the lungs. 26 The mechanics of breathing (continue) Auxiliary muscles of respiration During the forced inspiration (stronger than normal); Neck and Shoulder muscles (sternocleidomastoid and pectoralis) contract and Enlarges the thorax. During the forced expiration Abdominal, internal intercostal muscles contract and decrease thorax volume. exspiration inspiration 28 Muscles of Respiration The accessory muscles Exercise of inspiration are not involved during normal quiet breathing but may be called into play during exercise; during the inspiratory phase of coughing or sneezing; or in a pathologic state, such as asthma. Alveoli 300 millions of alveoli Total surface area 85 m2 Each alveolus has a very little amount of water in it. Surface tension occurs due to collapsing (shrivel, shrink) aim of the water molecules When a liquid interfaces with air, it tends to make its shape spherical. Such as seen in rain droplets. Thus, the very small amount of liquid in the alveoli, interfacing with air, tends to minimize its surface area (surface tension). This can cause difficulty to inflate the lungs. Fortunately, a substance secreted from the alveolar cells, called Surfactant prevents this surface tension Lung structure Alveoli: Function: Gas exchange Structure: Alveolar epithelial cells (type I) Surfactant (type II) Around alveoli, there is Capillary endothelium Ankara, Oct. 2006 33 ALVEOLUS ” Neonatal respiratory distress syndrome (RDS)” In the gestational period, the fetus’s lungs complete producing surfactant by 35. week, in the intrauterine life. If a baby is born before 26 weeks of the normal period, this premature infant (early born) will have a lack of surfactant and suffer respiratory distress syndrome. It is called Neonatal RDS. They exhibit atelectasis (lung collapse) and cannot inflate their lungs so the baby will suffer hypoxemia. TYPES of BREATHING Epnea: Normal breathing Apnea – Absence of breathing. e.g., Sleep apnea Dyspnea – Difficult or labored breathing Orthopnea - Changing of the breath due to positions (During congestive heart failure, asthma, and lung failure, Dyspnea mostly occurs when recumbent (lying), but can be relieved by sitting or standing. Dead Space Anatomic dead space is the normal volume of the conducting airways and approximately 150 ml. This volume of the pulmonary system does not participate in Gas Exchange. Physiologic dead space constitutes some of the nonfunctional alveoli due to some pathologies. It is defined as a volume of the lungs that does not participate in gas exchange. Differences between Pulmonary Ventilation and Alveolar Ventilation PULMONARY VENTILATION: the amount of air moved in and out of the lungs in one minute. We breathe about 12-20 times in one minute We get about 500mL air in each breath Pulmonary Ventilation = 500 x 12 = ~ 6000 mL/min (6 L/min) air ALVEOLAR (MINUTE) VENTILATION: the amount of air that moves in and out of the ALVEOLUS in one minute. We get 500 mL of air in one breath. 150 mL of it stays in the Anatomic Dead Space. In the alveoli 500 -150 =350 mL of air participate in gas Exchange. Alveolar minute ventilation = 350 x 12 = ~ 4200 mL/min (4,2 L/min) Alveolar ventilation alveolar ventilation = total ventilation minus ventilation of dead space The proportion of alveolar ventilation  increases with increasing tidal volume  decreases with increasing respiratory frequency an constant ventilation condition tidal frequency total dead alveolar of volume minute space ventilation breathing ventilation ventilation --------------------------------------------------------------------------------------------------shallow 150ml 40 6000ml 150 x 40 0ml normal 500ml 12 6000ml 150 x 12 4200ml deep 1000ml 6 6000ml 150 x 6 5100ml  deep breaths = large alveolar ventilation = improvement of gas exchange 40 Physics of Gases: Gas diffusion - Diffusion requires a concentration gradient - Diffusion goes from higher to lower concentration (“downhill”) O2 O2 consumes oxygen 42 Partial Atmospheric Pressures of Air Atmospheric pressure of air: 760 mm Hg in sea level Oxygen makes up 21% of atm pressure - Partial Oxygen pressure (PO₂): 760 x 0.21 = 160 mmHg Nitrogen makes up 78% of atm pressure - Partial nitrogen pressure: 760 x 0.78 = 600 mmHg Carbon Dioxide makes up 0.04% of atm pressure - Partial CO2 pressure (PCO₂): 760 x 0.0004=0.3 mmHg Bronchodilatation depends on; Airway resistance, When bronchus diameter increases, airway resistance decreases Physiologic Factors that cause bronchodilation Sympathetic nervous system activation (β₂ adrenergic receptors) – Adrenaline – Increased CO2 pressure – Nitric oxide (NO) Normal lung Smokers die 10 years early A British long-term study indicates that smokers die 10 years earlier than non-smokers. However, it’s worth stopping smoking at any time. Smoker‘s lung Some results were surprising: Those who stopped smoking at the age of 30 lived as long as nonsmokers. Men, who stopped before age 40 lived only one year less than non-smokers. Institute of Plastination, Heidelberg, 2004 46 Lung Volume and Capacities (Static Evaluation) EVALUATION of LUNG’S VOLUME and CAPACITIES by SPIROMETRY Volumen Volumen Volume Pulmonary ventilation: TIDAL VOLUME per each Breathing time Tidal volüme: 500 mL in each breathing Breathing frequency: 12-20 times/min 49 Pulmonary Volumes 1-The tidal volume (VT) is the volume of air inspired or expired with each normal breath; it is about 500 ml in the average adult male. 2- The inspiratory reserve volume (IRV) is the extra volume of air that can be inspired over and above the normal tidal volume when the person inspires with full force; it is about 3000 ml 3- The expiratory reserve volume (ERV) is the maximum extra volume of air that can be achieved by forceful expiration after the end of a normal tidal expiration; It is about 1100 ml 4- The residual volume (RV) is the volume of air remaining in the lungs even after the most forceful expiration. It is about 1200 ml Pulmonary Capacities 1 1-The inspiratory capacity (IC) equals the tidal volume plus the inspiratory reserve volume (IC=TV+IRV). The person begins to inspire from a normal expiratory level and continues to inspire forcefully. It is about 3500 ml 2. The functional residual capacity (FRC) is the amount of air that remains in the lungs at the end of normal expiration. FRC = expiratory reserve volume + the residual volume (FRC=ERV+RV). It is about 2300 ml Pulmonary Capacities 2 3. The vital capacity (VC) is the maximum amount of air a person can expel from the lungs after a forceful inspiration. VC consists of the inspiratory reserve volume and the tidal and expiratory reserve volumes. VC is about 4600 ml 4. The total lung capacity (TLC) is the maximum volume to which the lungs can be expanded with the greatest effort. TLC is equal to the vital capacity plus the residual volume. TLC is about 5800 ml IRV IC VC VT TLC ERV FRC RV DYNAMIC LUNG CAPACITIES (used to diagnose Lung Disease) It refers to the amount of air that can be expelled in one second. Normally 80% of the inspired air should be expelled in one second : Forced Expiratory Volume in one second/Forced Vital Capacity should be 80% (FEV1/FVC=80%) If the expiration is late, (