Respiratory System

1. Respiratory System Mr. Neuberger

2. Overview Breath represents life. The two most dramatic moments of the human experience are the first breath of a new born baby and the last gasp of a dying person The need to breath is driven by cellular demands for energy in the form of ATP; most ATP synthesis requires oxygen and generates carbon dioxide

3. Overview • The Respiratory System is an organ system specialized primarily to provide oxygen to the blood and remove carbon dioxide from it • It has a broader range of functions as well: • 1. Provides for oxygen and carbon dioxide exchange between blood and the air • 2. Serves for speech and other vocalizations • 3. Provides a sense of smell • 4. Controls pH of the body fluids (eliminates carbon dioxide) • 5. Lungs carry out a step in synthesis of vasoconstrictior • 6. Breathing creates pressure gradients between thorax and abdomen that promote blood flow of lymph and venous blood • 7. Taking a deep breath and holding it while contracting the abdominal muscles help expels wastes

4. Principle Organs Nose, Pharynx, Larynx, Trachea, Bronchi, and Lungs Within the lungs, air flows along a dead-end pathway consisting of bronchi-> bronchioles-> alveoli Incoming air stops in the alveoli, exchange gases with the bloodstream across the alveolar wall, and then flows back out

5. Divisions and Tracts Conducting Division- Consists of the passages that serve only for airflow, from the nostrils to the bronchioles Respiratory Division- Consists of the alveoli and other gas-exchange regions Upper Respiratory Tract- Airway from the nose through the larynx Lower Respiratory Tract- Airway from the trachea through the lungs

6. The Upper Respiratory Tract: Nose • The Nose has several functions • It warms, cleanses, and humidifies inhaled air • It detects odors in the airstream • Serves as a resonating chamber that amplifies the voice • Extends from a pair of anterior openings called the nostrils (nares)to a pair of posterior openings called the choanae (posterior nasal apertures) • The facial part of the nose is shaped by bone and hyaline cartilage, flared portion of the lower end is called the alanasi • The nasal cavity begins with a small dialated chamber called the vestibule, has stiff guard hairs or vibrissae • Divided into left and right halves called nasal fossae, divided by septum • The roof of the nasal cavity is formed by the ethmoid and sphenoid bones, and the hard palate forms the floor. Allows you to breathe while you chew • The nasal cavity receives drainage from the paranasal sinuses and the nasolacrimal ducts of the orbits

7. Nose • Most of the area in the nasal cavity is occupied by 3 folds of tissue, superior, middle, inferior nasal conchae, project from the lateral walls • Beneath each concha is a narrow air passage called a meatus • Odors are detected by the sensory cells in the olfactory epithelium which covers a small area of the roof of the nasal fossa and adjacent parts of the septum and superior concha • The rest of the nasal cavity is lined with respiratory epithelium • Both are ciliated pseudostratified columnar epithelia, • Olfactory is immobile, respiratory is mobile • Lamina propria (connective tissue layer beneath the epithelium) is well populated by lymphocytes that mount immune defenses against inhaled pathogens • Also contain large blood vessels that help to warm the air • The inferior concha has erectile tissue • Every 30-60 minutes, the erectile tissue on one side becomes engorged with blood to restrict airflow to that fossa, prevents drying

8. The Pharynx • The pharynx is a muscular funnel extending about 5in from the choanae to the larynx, it has 3 regions- nasopharynx, oropharynx, and laryngopharynx • Nasopharynxlies posterior to the choanae and soft palate. • It receives the auditory tubes from the middle ears and houses the pharyngeal tonsil. Inhaled air turns 90º as it passes through the nasopharynx • Passes only air • Lined with pseudostratified columnar epithelium • Oropharynx is a space between the soft palate and root of the tongue, contains the palatine and lingual tonsils • Passes food, air, and drink • Lined with stratified squamous epithelium • Laryngopharynx begins with the union of the nasopharynx and oropharynx at the level of the hyoid bone • Passes food, air and drink • Lined with stratified squamous epithelium

10. Warm Up 3.5.12 1. 6 principle organs of the Respiratory system 2. Define conducting and respiratory division 3. Provide 4 facts about the nose

11. The Larynx • The Larynx or “voice box” is a cartilaginous chamber about 4.5 cm long • Primary function is to keep food and drink out of the airway, but evolved an additional role of sound production (phonation) • Superior opening of the larynx is guarded by a flap of tissue called the epiglottis, at rest it stands almost vertically • The framework of the larynx consists of 9 cartilages, first 3 are solitary and relatively large • Most superior one is the epiglottic cartilage- a spoon-shaped supportive plate • The largest is the thyroid cartilage- named for its sheild-like shape, the “Adam’s apple” is called the laryngeal prominence • Cricoid Cartilage- connects the larynx to the trachea

12. The Larynx • The remaining cartilages are smaller and occur in three pairs • Posterior to the thyroid cartilage are two arytenoid cartilages, attached to their upper ends are a pair of little horns, corniculate cartilages • The arytenoid and corniculate cartilages function in speech • A pair of cuneiform cartilages support the soft tissues between the arytenoids and the epiglottis • There is a group of fibrous ligaments that bind the cartilages of the larynx together and to adjacent structures in the neck • Superiorly, a broad sheet called the thyrohyoid ligament joins the thyroid cartilage to hyoid bone • Inferiorly, the cricotracheal ligament joins the cricoid cartilage to the trachea

13. The Larynx • The walls of the larynx are also quite muscular • Deep intrinsic muscles operate the vocal cords, and the superficial extrinsic muscles connect the larynx to the hyoid bone and elevate the larynx during swallowing • Two pairs of intrinsic ligaments, vestibular and vocal ligaments, extend from the thyroid cartilage in front to the arytenoid cartilages in back • Support the vestibular folds and vocal cords, respectively • The inferior vocal cords produce sound when air passes between them • Covered with stratified squamous epithelium, best suited to endure vibration and contact between the cords • The vocal cords and the space between them are collectively called the glottis

14. How the Vocal Cords Work • The intrinsic muscles control the vocal cords by pulling on the corniculate and arytenoid cartilages, causing the cartilage to pivot • Depending on their direction of rotation, the arytenoid cartilages abduct or adduct the vocal cords • Air forced between the adducted vocal cords vibrates them, producing a high-pitched sounds when the cords are taught, and a low-pitched sound when they are relaxed • Male vocal cords are longer and thicker, vibrates slower, and produce lower-pitched sounds than in females • Loudness is determined by the force of the air passing through the vocal cords • Words are formed by actions of the pharynx, oral cavity, tongue, and lips

16. Lower Respiratory Tract Below the larynx, just above the beginning of the sternum, your lower respiratory tract starts It is located entirely within your thoracic region Extends from the trachea to the pulmonary alveoli

17. The Trachea and Bronchi • The trachea or “wind pipe” is a tube about 11cmlong and 1 inch in diameter, lying anterior to the esophagus • It is supported by 16-20 C-shaped rings of hyaline cartilage • The inner lining of the trachea is pseudostratified columnar epithelia composed mainly of mucus-secreting goblet cells, ciliated cells, and short basal stem cells • The mucus traps inhaled particles, the cilia moves it up towards the pharynx where it is swallowed • This mechanism of debris removal is called the mucociliary escalator

18. The Trachea and Bronchi • The connective tissue beneath the tracheal epithelium contains lymphatic nodules, mucous and serous glands, and the tracheal cartilages • The open part of the C faces posteriorly • Allows the esophagus room to expand as swallowed food passes by • The gap is spanned by smooth muscle tissue called the trachealis • Contraction of this muscle narrows or widens the trachea to adjust airflow • The outermost layers of the trachea, adventitia, is fibrous connective tissue that blends into the adventitia of other organs of the mediastinum

19. The Trachea and Bronchi At vertebra T5, the trachea forks into a left and right main bronchi The lowermost tracheal cartilage has an internal median ridge called the carina that directs the airflow to the right and left

20. The Lungs • Each lung is a conical organ with a broad, concave base resting on the diaphragm and a blunt peak called the apex projecting slightly above the clavicle • The broad costal surface is pressed against the rib cage, the smaller concave mediastinal surface faces medially • MS also has a small slit called the hilum- where the lung receives the main bronchus, blood vessels, lymphatic vessels, and nerves • Root of the lung

21. Positioning and Size • The right lung is shorter than the left because the liver rises higher on the right • The left lung is narrower than the right because the heart tilts towards the left and occupies more space • The left lung has a cardiac impression where the heart presses against it • Rt. Lung has 3 lobes- superior, middle, and inferior • Has a groove called horizontal fissure separates the sup. lobe from the mid lobe. Oblique fissure separates the mid. from inf. lobe • Left lung only has oblique fissure

22. The Bronchial Tree • Each lung contains a branching system of air tubes called the bronchial tree, extending from the main bronchus to the terminal bronchioles • Larger than the left, consequently more objects get lodged in there • Gives off a superior lobar bronchus as well, projects into the superior lobe of the lung • Main continues down and branches into the middle and inferior lobar bronchi • In each lung, each lobar bronchus branches into segmental (tertiary) bronchi • Each one of these ventilates one functionally independent unit of lung tissue called a bronchopulmonary segment. 10 in right lung, 8 in left

23. The Bronchial Tree • The main bronchi are supported by C-shaped hyaline cartilages • Lobar and segmental bronchi are supported by overlapping crescent-shaped cartilaginous plates • Lined with the same epithelia as the trachea but the cells grow shorter and thinner as you progress distally • Lamina propria beneath, contains mucus glands and lymphocytes • All divisions of the bronchial tree have a substantial amount of elastic connective tissue • Contributes to the recoil that expels air from the lungs in each respiratory cycle • The mucosa also has a well-developed layer of smooth muscle, which regulates airway diameter and airflow

24. The Bronchial Tree • Bronchioles are continuations of the airway that lack supportive cartilage • Portion of the lung that is ventilated by one bronchiole is called a pulmonary lobule • Lack mucus glands and goblet cells, although they are ciliated throughout • Continue past where mucus is produced, ensures clearing • Mucosa of the bronchioles consist mainly of smooth muscle • Each bronchiole divides into 50-80 terminal bronchioles, final branches of the conducting division, 65,000 in each lung

25. The Bronchial Tree • Each terminal bronchiole gives off two or more respiratory bronchioles, which have alveoli budding from their walls • Beginning of the respiratory division • Each RB divides into 2-10 elongated, thin-walled passages called alveolar ducts, which also have alveoli on their walls • The ducts end in alveolar sacs, which are grape-like clusters of alveoli arrayed around a central space called the atrium

26. The Bronchial Tree • Air in the CD of the respiratory tract cannot exchange gasses with the blood, therefore it’s called dead air • The lumen of the CD is called the anatomic dead space • In a state of relaxation, parasympathetic nerve fibers stimulate muscularis mucosae and keep the airway partially constricted. • Minimizes dead space so that a greater percentage of inhaled air goes to the alveoli where it can oxygenate the blood

27. The Bronchial Tree • During exercise, sympathetic nerves relax the smooth muscle and dilate the airway • Increases dead space, however it enables air to flow more easily and rapidly so the alveoli can be ventilated in proportion to exercise • The bronchioles exert the greatest control over airflow for two reasons • (1) They are the most numerous component of the conducting division • (2) With their well-developed smooth muscle and lack of confining cartilage, they can change relative diameter more than the larger air passages can • Bronchoconstriction • Bronchodilation

28. The Bronchial Tree The lungs receive a blood supply from the pulmonary arteries and bronchial arteries Branches of the pulmonary artery closely follow the bronchial tree on their way to the capillaries surrounding the alveoli Lungs are the only organs to receive both a pulmonary and systemic blood supply

29. Alveoli • Each lung is a spongy mass with about 150 million little sacs, or alveoli, which provide 70m² of surface for gas exchange • An alveolus is a pouch about 0.2 to 0.5 mm in diameter • Thin, broad cells called squamous (type I) alveolar cells cover about 95% of the alveolar surface area • Their thinness allows for rapid gas diffusion • Great (type II) alveolar cells cover the other 5%, they have 2 functions • (1) Repair the alveolar epithelium when the squamous alveolar cells are damaged • (2) They secrete pulmonary surfactant, prevents alveoli and smallest bronchioles from collapsing during an exhale

30. Alveoli • The most numerous cells in the lung are the alveolar macrophages (dust cells), wander the lumens of the alveoli and the connective tissue between them • These cells keep the alveoli free of debris by phagocytizing dust particles that escape entrapment by mucus in the higher parts of the RT • In lungs that are infected or bleeding, the macrophages also phagocytize bacteria and loose blood cells • 100 million perish each day and ride up the mucociliary escalator

31. Alveoli • Each alveolus is surrounded by a basket of blood capillaries supplied by the pulmonary artery • The barrier between them is called the respiratory membrane, it consists only of the squamous alveolar cell, the squamous endothelial cell of the capillary, and their shared basement membrane • Alveoli must be kept dry, easier to diffuse gasses that way • Lungs have a more extensive lymphatic drainage system than any other organ in the body

32. The Pleurae • The surface of the lung is covered by a serous membrane, the visceral pleura, which extends into the fissures • At the hilum, the visceral pleura turns back on itself and forms the parietal pleura, which adheres to the mediastinum, inner surface of the rib cage, and superior surface of the diaphragm • Pulmonary ligament attaches it to the diaphragm

33. The Pleurae The space between the parietal and visceral pleurae is called the pleural cavity The two membranes are normally separated by a film of slippery pleural fluid, the pleural cavity is a potential space, normally no room between the membranes

34. The Pleurae • The pleurae and pleural fluid have 3 functions • 1. Reduction of friction- pleural fluid acts as a lubricant that enables the lungs to expand and contract with minimal friction • 2. Creation of a Pressure Gradient-During inspiration, the rib cage expands and draws the parietal pleura outward along with it. The air pressure within the lung drops below the atmospheric pressure outside the body, and outside air flows down its pressure gradient into the lung • 3. Compartmentalization- The pleurae, mediastinum, and pericardium compartmentalize the thoracic organs and prevent infections of one organ from spreading easily to neighboring organs

35. The Respiratory Muscles • The lungs do not ventilate themselves. The only muscle they contain is smooth muscle in the walls of the bronchi and bronchioles, which does not create the airflow but only affects its speed • The Prime mover is the diaphragm, muscular dome that separates the thoracic cavity from the adominal cavity, accounts for 2/3 of the pulmonary airflow • When relaxed, it bulges upwards to its farthest extent, pressing the base of the lungs, lungs at minimum volume • When the diaphragm contracts, it tenses and flattens, enlarges the thoracic cavity and the lungs and causes an inflow of air

36. The Respiratory Muscles • Several other muscles aid in the diaphragm as synergists. Internal and external intercostal muscles • Their primary function is to stiffen the thoracic cage during respiration and prevent it from caving inward when the diaphragm descends • Attributes to the enlargement and contraction of the thoracic cage, adds 1/3 of the air that ventilate the lungs

37. Respiratory Physiology • The pressure in the air in the atmosphere is 760 mmHg. Air in the alveoli at the end of one expiration and before the beginning of another inspiration also exerts a pressure of 760 mmHg • When atmospheric pressure is greater than pressure within the lung, air flows down this gas pressure gradient, inspiration • When pressure in the lungs becomes greater than atmospheric pressure, air again moves down a gas pressure gradient, moves outward, expiration

38. Inspiration Diaphragm contracts, makes the thoracic cavity longer. Contraction of the external intercostal muscles pull the anterior end of each rib up and out. Elevates the attached sternum, expands thoracic cavity side-to-side and front-to-back The tendency of the thorax and lungs to return to their pre-inspiration volume is called elastic recoil

39. Expiration Inspiratory muscles relax and thus make the thoracic cavity smaller, pushes air out The ability of the lungs and thorax to stretch, or compliance, is essential to normal respiration During expiration, the negative intrapleural pressure must overcome the “collapse tendency of the lungs” caused by the surface tension of the fluid lining the alveoli and the stretch of elastic fibers

40. Pulmonary Volumes Spirometer is used to measure the volume of air exchanged in breathing Tidal Volume (TV)- The volume of air exhaled normally after a typical inspiration, 500 ml in adults Expiratory Reserve Volume (ERV)- The largest additional volume of air that one can forcibly expire after expiring tidal air, 1,000-1,200 ml Inspiratory Reserve Volume (IRV)- The amount of air that can be forcibly inspired over and above a normal inspiration, 3,300 ml Residual Volume (RV)- The amount of air that cannot be forcibly expired, 1,20o ml Vital Capacity (VC)- IRV + TV + ERV

41. Transport of Oxygen • Oxygen will combine with hemoglobin to form oxyhemoglobin. It will also be present in the blood plasma as well • Normal arterial blood will have about 20 vol% Oxygen • 20ml of oxygen per 100ml of blood • The more hemoglobin the capillaries in the lung contain, the more oxygen they can carry • 97% absorption rate in hemoglobin

42. Transport of Carbon Dioxide Only about 10% is carried in dissolved form in plasma 25% attaches to amine groups of the amino acids that make up the polypeptide chains of hemoglobin, and proteins as well The rest is carried in the form of bicarbonate ions