Respiratory System Lecture PDF

RESPIRATORY SYSTEM Dr. Maria Criselda M. Bonifacio-Uy, RN, AFPAAAMMI  Anatomy Oxygen is required for the body’s cells to synthesize the chemical energy molecule, ATP Carbon dioxide is a by-product of ATP production and must be removed from the blood Inc...

RESPIRATORY SYSTEM Dr. Maria Criselda M. Bonifacio-Uy, RN, AFPAAAMMI  Anatomy Oxygen is required for the body’s cells to synthesize the chemical energy molecule, ATP Carbon dioxide is a by-product of ATP production and must be removed from the blood Increased levels of CO2 will lower the pH of the blood Blood pH must be maintained within relatively narrow limits to maintain homeostasis  Anatomy STRUCTURES OF THE RESPIRATORY SYSTEM 1. External nose. The external nose encloses the chamber for air inspiration. Although air can be inspired through the mouth, the mouth is part of the digestive system rather than the respiratory system. 2. Nasal cavity. The nasal cavity is a cleaning, warming, and humidifying chamber for inspired air. 3. Pharynx. The pharynx is commonly called the throat. It serves as a shared passageway for food and air. 4. Larynx. The larynx is frequently called the voice box. Its rigid structure helps keep the airway constantly open, or patent.  Anatomy STRUCTURES OF THE RESPIRATORY SYSTEM 5. Trachea. The trachea is commonly known as the windpipe. It serves as an air- cleaning tube to funnel inspired air to each lung. 6. Bronchi. The bronchi are tubes that direct air into the lungs. 7. Lungs. Each lung is a labyrinth of air tubes and a complex network of air sacs, called alveoli, and capillaries. The air sacs are separated by walls of connective tissue containing both collagenous and elastic bers. Each air sac is the site of gas exchange between the air and the blood. fi  Anatomy THE NOSE The only externally visible part of the respiratory system Air enters the nose by passing through the nostrils/nares Interior nose consist of the NASAL CAVITY; divided by the NASAL SEPTUM Olfactory receptors -located in the mucosa in the slitlike superior part of the nasal cavity just beneath the ethmoid bone Respiratory mucosa - lining of the nasal cavity; rest in the rich network of think walled veins that warms the air as it ows Sticky mucus produced by this mucosa’s glands moisten the air and traps incoming bacteria and other foreign debris, and lysozyme enzymes in the mucus destroy bacteria fl  Anatomy THE NOSE Ciliated cells - moves contaminate mucus to the throat (pharynx) and swallowed and digested by stomach juices Conchae - mucosa-covered projections; increase the air turbulence in the nasal cavity Palate - separates the oral cavity and nasal cavity Hard palate - anterior part; supported by bone Soft palate - unsupported posterior part Paranasal sinuses - frontal, sphenoid, ethmoid and maxillary Ligthen the skull and act as resonance chambers for speech Produce mucus, which drains into the nasal cavities  Anatomy THE NOSE Rhinitis - caused by cold viruses and various allergens; in ammation of the nasal mucosa Excessive mucus produced results in nasal congestion and postnasal drip Sinusitis - sinus in ammation; di cult to treat and can cause marked changes in voice quality. fl ffi fl  ANATOMY PHARYNX A muscular passageway about 13cm (5inches) long Common passageway for food and air Continuous with the nasal cavity anteriorly via the posterior nasal aperture  ANATOMY PHARYNX 3 regions NASOPHARYNX OROPHARYNX LARYNGOPHARYNX  ANATOMY PHARYNX Food enters the mouth then travels the same route as air through the oropharynx and laryngopharnx —> directed towards the esophagus posteriorly by a ap called EPIGLOTTIS Pharyngotympanic tube - drains the middle ears, opens into the nasopharync fl  ANATOMY PHARYNX Pharyngeal tonsil/ Adenoid - located high in the nasopharynx Palatine Tonsils - paired, at the end of the soft palate in the oropharynx Lingual tonsils - lie at the base of the tongue Tubal tonsils - protect the openings of the pharyngotympanic tube Tonsils play a role in protecting the body from infections ANATOMY PHARYNX ANATOMY PHARYNX  ANATOMY LARYNX Voice box Routes air and food into the proper channels Plays a role in speech Located inferior to the pharynx Formed by 8 rigid hyaline cartilages and spoon-shaped ap of elastic cartilage - EPIGLOTTIS THYROID CARTILAGE - shield-shaped largest hyaline cartilage, protrudes anteriorly; aka the Adam’s apple fl  ANATOMY LARYNX Voice box Routes air and food into the proper channels Plays a role in speech Located inferior to the pharynx Formed by 8 rigid hyaline cartilages and spoon-shaped ap of elastic cartilage - EPIGLOTTIS THYROID CARTILAGE - shield-shaped largest hyaline cartilage, protrudes anteriorly; aka the Adam’s apple fl  ANATOMY LARYNX Epiglottis - spoon shaped ap of elastic cartilage Guardian of the airway Protects the superior opening of the larynx Allows the passage of air into the lower respiratory passage - during regular breathing During deglutition - the larynx is pulled upward and the epiglottis tips forwards covering the larynx’s opening Cough re ex - triggered to prevent substances other than air from entering the lungs DO NOT GIVE WATER TO AN UNCONSCIOUS PERSON fl fl  ANATOMY LARYNX Vocal folds/ True vocal cords - paired folds; vibrates with expelled air; allows us to speak Glottis - slitlike passage way between the vocal folds  ANATOMY TRACHEA Trachea or windpipe - 10 -12 cm (4 inches) in length Travels from the larynx down at the level of the fth thoracic vertebra Rigid, its walls is made up of C shaped rings of hyaline cartilage The open part of the rings abut the esophagus and allows it to expand anteriorly when we swallow a large piece of food The solid portions support the trachea walls and keep it patent or open fi  ANATOMY RESPIRATORY ZONE STRUCTURES and RESPIRATORY MEMBRANE  ANATOMY TRACHEA Trachea or windpipe - Trachealis muscle lies next to the esophagus and completes the wall of the trachea posteriorly Lined with ciliated mucosa Cilia beat continuously in a superior direction Surrounded by goblet cells that produce mucus Propels mucus loaded with dust particles away from the lungs to the throat  ANATOMY THE MAIN BRONCHI Right and Left Main (Primary) Bronchi Formed by the division of the trachea. Runs obliquely before it plunges into teh medial depression or hilum of the lungs on its own side Right main bronchus - is wider, shorted and straighter Most common site for an inhaled foreign object to become lodged ANATOMY THE MAIN BRONCHI ANATOMY THE MAIN BRONCHI  ANATOMY THE LUNGS Fairly large organ Weighs about 2 1/2 pounds; soft and spongy Occupy the entire thoracic cavity Apex - the narrow superior portion of each lung Just deep to the clavicle Base - broad area resting on the diaphragm Each lung is divided into lobes by ssues; left lung has two lobes and right lung has 3 lobes fi  ANATOMY THE LUNGS Pulmonary pleura/visceral pleura - covers the surface of the lungs Parietal pleura - covers the walls of the thoracic cavity Pleural uid - produced by the pleural membrane; slippery serous uid, allows the lungs to glide easily over the thorax wall Pleural space - more of a potential space than an actual one fl fl  ANATOMY THE LUNGS Pulmonary pleura/visceral pleura - covers the surface of the lungs Parietal pleura - covers the walls of the thoracic cavity Pleural uid - produced by the pleural membrane; slippery serous uid, allows the lungs to glide easily over the thorax wall Pleural space - more of a potential space than an actual one fl fl  ANATOMY THE BRONCHIAL TREE The main bronchus subdivide into smaller and smaller branches (secondary and tertiary bronchi and so on) ending on the conducting passageways the BRONCHIOLES Bronchial/Respiratory tree - the network from from the branching and rebranching of the respiratory passageways within the lungs  ANATOMY RESPIRATORY ZONE STRUCTURES and RESPIRATORY MEMBRANE Alveoli/ Air sacs - tiny air sacs at the ends of terminal bronchioles; are respiratory zone structures Respiratory zone - includes respiratory bronchioles, alveolar ducts, alveolar sacs and alveoli - the ONLY site for gas exchange Conducting zone structures - the rest of the respiratory passages; serves are conduits to and from the respiratory zone  ANATOMY RESPIRATORY ZONE STRUCTURES and RESPIRATORY MEMBRANE  ANATOMY RESPIRATORY ZONE STRUCTURES and RESPIRATORY MEMBRANE  ANATOMY RESPIRATORY ZONE STRUCTURES and RESPIRATORY MEMBRANE There are millions of the clustered alveoli, which resemble bunches of grapes, and they make up the bulk of the lungs The balance of the lung tissue, its stroma, is mainly elastic connective tissue that allows the lungs to stretch and recoil (spring back) as we breathe The walls of the alveoli are composed largely of a single, thin layer of simple squamous epithelial cells.  ANATOMY RESPIRATORY ZONE STRUCTURES and RESPIRATORY MEMBRANE Alveolar pores connect neighboring air sacs and provide alternative routes for air to reach alveoli whose feede bronchioles have been clogged by mucus or otherwise blocked. The alveolar and capillary walls, their fused basement membranes, and occasional elastic bers construct the respiratory membrane (air-blood barrier) Gas exchange occurs by simple di usion through the respiratory membrane-oxygen passes from the alveolar air into the capillary blood, and carbon dioxide leaves the blood to enter the alveoli ff fi  ANATOMY RESPIRATORY ZONE STRUCTURES and RESPIRATORY MEMBRANE  ANATOMY RESPIRATORY ZONE STRUCTURES and RESPIRATORY MEMBRANE The nal line of defense for the respiratory system is in the alveoli. Remarkably e cient alveolar macrophages, sometimes called "dust cells" wander in and out of the alveoli picking up bacteria, carbon particles, and other debris. Also scattered amid the epithelial cells that form most of the alveolar walls are cuboidal surfactant-secreting cells, which look very di erent from the squamous epithelial cells. These cells produce a lipid (fat) molecule called surfactant, which coats the gas-exposed alveolar surfaces and is very important in lung function fi ff ffi  PHYSIOLOGY Major function: supply the body with oxygen and to dispose of carbon dioxide 4 events of Respiration 1. Pulmonary ventilation. Air must move into and out of the lungs so that the gases in the alveoli of the lungs are continuously refreshed. This process of pulmonary ventilation is commonly called breathing.  PHYSIOLOGY 4 events of Respiration 2. External respiration. Gas exchange (oxygen loading and carbon dioxide unloading) between the pulmonary blood and alveoli must take place. Remember that in external respiration, gas exchanges are being made between the blood and the body exterior.  PHYSIOLOGY 4 events of Respiration 3. Respiratory gas transport. Oxygen and carbon dioxide must be transported to and from the lungs and tissue cells of the body via the bloodstream. 4. Internal respiration. At systemic capillaries, gas exchange occurs between the blood and cells inside the body. This time, oxygen is unloaded from blood and CO, is loaded.  PHYSIOLOGY MECHANISM OF BREATHING Breathing or pulmonary ventilation - is a mechanical process that depends on teh volume changes occurring in the thoracic cavity Volume changes lead to pressure changes, which lead to the ow of gases to equalize the pressure. fl  PHYSIOLOGY MECHANISM OF BREATHING Inspiration When the inspiratory muscles, the diaphragm and external intercostals, contract, the size (volume) of the thoracic cavity increases. As the dome-shaped diaphragm contracts inferiorly, the superior-inferior dimension (height) of the thoracic cavity increases Contraction of the external intercostals lifts the rib cage and thrusts the sternum forward, which increases the anteroposterior and lateral dimensions of the thorax.  PHYSIOLOGY MECHANISM OF BREATHING Inspiration / Inhalation The lungs adhere tightly to the thorax walls and are stretched to the new, larger size of the thorax. As intrapulmonary volume increases, the gases within the lungs spread out to ll the larger space. The resulting decrease in gas pressure in the lungs produces a partial vacuum (lung pressure is less than the atmospheric pressure) causes air ow to the lungs; air continues to move into the lungs until intrapulmonary pressure equals atmospheric pressure fi fl  PHYSIOLOGY MECHANISM OF BREATHING Expiration (exhalation) A passive process that depends more on the natural elasticity of the lungs than on muscle contraction Inspiratory muscles relax and resume resting length, the rib cage descends, the diaphragm relaxes superiorly and the lungs recoil Both the thoracic and intrapulmonary volumes decrease.  PHYSIOLOGY MECHANISM OF BREATHING Expiration (exhalation) As the intrapulmonary volume decreases, the gases inside the lungs are forced more closely together, and the intrapulmonary pressure rises to a point higher than atmospheric pressure This causes the gases to passively ow out to equalize the pressure with the outside. fl  PHYSIOLOGY MECHANISM OF BREATHING if the respiratory passageways are narrowed by spasms of the bronchioles (as in asthma) or clogged with mucus or uid (as in chronic bronchitis or pneumonia), expiration becomes an active process. In such cases of forced expiration, the internal intercostal muscles are activated to help depress the rib cage, and the abdominal muscles contract and help to force air from the lungs by squeezing the abdominal organs upward against the diaphragm. fl  PHYSIOLOGY MECHANISM OF BREATHING Normally the pressure within the pleural space the intrapleural pressure, is always negative (meaning it is lower than the pressure inside the lungs). This is the major factor preventing lung collapse. If for any reason the intrapleural pressure becomes equal to the atmospheric pressure, the lungs immediately recoil and collapse.  PHYSIOLOGY MECHANISM OF BREATHING Atelectasis or lung collapse - the lung is useless for ventilation Occurs when air enters the pleural space through a chest wound or a rupture of the visceral pleura Pneumothorax- air in the intrapleural space, pushes in on the lung, disrupting the uid bond between the pleurae Reversed by drawing air out of the intrapleural space with a chest tube; which allows the lungs to rein ate and resume normal function fl fl  PHYSIOLOGY RESPIRATORY VOLUMES AND CAPACITIES Normal quiet breathing moves approximately 500ml of air into and out of the lungs with each breath Tidal Volume (TV) - respiratory volume Inspiratory reserve volume (IRV) - the amount of air that can be taken in forcibly above the TV; approx: 3,100ml Expiratory reserve volume (ERV) - the amount of air that can be forcibly exhaled beyond tidal expiration; approx 1,200ml Residual Volume - the amount of air that remained in the lungs and cant voluntarily be expelled; approx 1,200ml; allows gas exchange to go on continuously even between breath and helps to keep alveoli open  PHYSIOLOGY RESPIRATORY VOLUMES AND CAPACITIES Vital Capacity - total amount of exchangeable air; approx 4,800ml in healthy men and 3,100ml in healthy women VC = TV + IRV + ERV Dead space volume - the air that enter the respiratory passageways and never reacher the alveoli to participate in gash exchange; about 150ml The functional volume-air that actually reaches the respiratory zone and contributes to gas exchange is about 350 ml.  PHYSIOLOGY RESPIRATORY VOLUMES AND CAPACITIES Spirometer - measures respiratory capacities Useful for evaluating losses in respiratory function and in following the course of some respiratory disease  PHYSIOLOGY RESPIRATORY VOLUMES AND CAPACITIES Nonrespiratory Air Movements  PHYSIOLOGY RESPIRATORY VOLUMES AND CAPACITIES Respiratory Sounds Bronchial sounds - are produced by air rushing through the large respiratory passageways (trachea and bronchi). Vesicular breathing sounds occur as air lls the alveoli. The vesicular sounds are soft murmurs that resemble a mu ed breeze. ffl fi  PHYSIOLOGY RESPIRATORY VOLUMES AND CAPACITIES  PHYSIOLOGY RESPIRATORY VOLUMES AND CAPACITIES Abnormal Lung Sounds Crackle/Rales - bubbling sound Wheezing - whistling sound Rhonchi - resemble snoring Stridor - wheeze-like sound heard Pleural Friction Rub - nonmusical, short sound, creaking or grating  PHYSIOLOGY RESPIRATORY VOLUMES AND CAPACITIES  PHYSIOLOGY EXTERNAL RESPIRATION, GAS TRANSPORT AND INTERNAL RESPIRATION Blood returning from the body delivers CO2 to the lungs as it picks up O2 In the systemic circuit, blood delivers O to body tissues and picks up CO2. External respiration is the actual exchange of gases between the alveoli and the blood (pulmonary gas exchange), and internal respiration is the gas exchange process that occurs between the blood and the tissue cells (systemic capillary gas exchange).  PHYSIOLOGY EXTERNAL RESPIRATION, GAS TRANSPORT AND INTERNAL RESPIRATION Gas exchanges obey the laws of di usion; that is, movement occurs toward the area of lower concentration of the di using substance. The relative amounts of O and CO, in the alveolar tissues, and in the arterial and venous blood ff ff PHYSIOLOGY  PHYSIOLOGY EXTERNAL RESPIRATION, GAS TRANSPORT AND INTERNAL RESPIRATION External Respiration Dark red blood (reduced oxygen) owing through the pulmonary circuit is transformed into the scarlet (high in oxygen) river that is returned to the heart for distribution to the systemic circuit. Body cells continually remove oxygen from blood, there is always more oxygen in the alveoli than in the blood Oxygen tends to di use from the air of the alveoli through the respiratory membrane into the more oxygen poor blood of the pulmonary capillaries ff fl  PHYSIOLOGY EXTERNAL RESPIRATION, GAS TRANSPORT AND INTERNAL RESPIRATION External Respiration as tissue cells remove oxygen from the blood in the systemic circulation, they release carbon dioxide into the blood. Because the concentration of carbon dioxide is much higher in the pulmonary capillaries than it is in the alveolar air, it will di use from the blood into the alveoli and be ushed out of the lungs during expiration. fl ff  PHYSIOLOGY EXTERNAL RESPIRATION, GAS TRANSPORT AND INTERNAL RESPIRATION Gas Transport in the Blood Oxyhemoglobin (HbO2) - oxygen attaches to hemoglobin inside the RBC; very small amount of O2 is carried dissolved in the plasma CO2 is 20 times more soluble in plasma; is transported in plasma as bicarbonate ion (HCO3) - which plays an important role in bu ering blood pH Is enzymatically converted to bicarbonate ion within RBC ff  PHYSIOLOGY EXTERNAL RESPIRATION, GAS TRANSPORT AND INTERNAL RESPIRATION Gas Transport in the Blood A smaller amount of the transported CO2 (between 20 and 30 percent) is carried inside the RBCs bound to hemoglobin. Carbon dioxide binds to hemoglobin at a di erent site from oxygen, so it does not interfere with oxygen transport. Bicarbonate ions (HCO3) must enter the red blood cells, where they combine with hydrogen ions (H+) to form carbonic acid (H2CO3). Carbonic acid quickly splits to form water and carbon dioxide, and carbon dioxide then di uses from the blood into the alveoli. ff ff  PHYSIOLOGY EXTERNAL RESPIRATION, GAS TRANSPORT AND INTERNAL RESPIRATION  PHYSIOLOGY EXTERNAL RESPIRATION, GAS TRANSPORT AND INTERNAL RESPIRATION Internal Respiration The exchange of gases between the blood and the tissue cells, is the opposite of what occurs in the lungs. Oxygen leaves and carbon dioxide enters the blood In the blood, carbon dioxide combines with water to form carbonic acid (H2CO3), which quickly releases bicarbonate ions  PHYSIOLOGY EXTERNAL RESPIRATION, GAS TRANSPORT AND INTERNAL RESPIRATION Internal Respiration Most of the conversion of carbon dioxide to bicarbonate ions occurs inside the RBCs, where a special enzyme (carbonic anhydrase) speeds up this reaction. Bicarbonate ions di use out into plasma, where they are transported. Oxygen is released from hemoglobin, and the oxygen di uses quickly out of the blood to enter the cells. Venous blood in the systemic circulation is much poorer in oxygen and richer in carbon dioxide than blood leaving the lungs. ff ff  PHYSIOLOGY CONTROL OF RESPIRATION Neural Regulation Neural centers that control respiratory rhythm and depth are located mainly in the medulla oblongata and pons Impulses from the Ventral Respiratory Group maintain a normal quiet breathing rate of 12 to 20 respirations/ minute, a rate called eupnea Hyperpnea - vigours and deep breathing  PHYSIOLOGY CONTROL OF RESPIRATION Non Neural Factors Physical Factors - increase in temperature, exercise, talking, coughing Volition (Conscious control) - singing, swallowing, swimming Emotional Factors Chemical factors - levels of CO2 and O2 in the blood Hyperventilation - is an increase in the rate and depth of breathing that exceeds the body’s need to remove CO2  PHYSIOLOGY CONTROL OF RESPIRATION Non Neural Factors Physical Factors - increase in temperature, exercise, talking, coughing Volition (Conscious control) - singing, swallowing, swimming Emotional Factors Chemical factors - levels of CO2 and O2 in the blood Hyperventilation - is an increase in the rate and depth of breathing that exceeds the body’s need to remove CO2  PHYSIOLOGY READ ON RESPIRATORY DISORDERS COPD CHRONIC BRONCHITIS EMPHYSEMA LUNG CA AdenoCA Squamous Cell CA Small Cell CA ASTHMA SLEEP APNEA  PHYSIOLOGY DEVELOPMENTAL ASPECTS In the fetus, the lungs are lled with uid, and all respiratory exchanges are made by the placenta. At birth, the uid- lled pathway is drained, and the respiratory passageways ll with air. The alveoli in ate and begin to function in gas exchange, but the lungs are not fully in ated for 2 weeks. The success of this change--that is, from nonfunctional to functional respiration- depends on the presence of surfactant, a fatty molecule made by the cuboidal alveolar cells. Surfactant lowers the surface tension of the lm of water lining each alveolar sac so that the alveoli do not collapse between each breath. Surfactant is not usually present in large enough amounts to accomplish this function until late in pregnancy (between 28 and 30 weeks). fl fl fl fi fi fl fi fi  PHYSIOLOGY DEVELOPMENTAL ASPECTS Respiratory rate Newborn: 40-80 cpm 5 years: 25 cpm Adults: 12-20 cpm  PHYSIOLOGY DEVELOPMENTAL ASPECTS Infant respiratory distress syndrome (IRDS) - infants who are born prematurely before 28 weeks or in whom surfactant production is inadequate Cystic Fibrosis - a lethal genetic birth defect; causes oversecretion of a thick mucus that clogs the respiratory passages and puts the child at risk for fatal respiratory infections. Sudden Infant Death Syndrome (SIDS) - crib death; apparently healthy infants stop breathing and die in their sleep.