RESPIRATORY SYSTEM

1. RESPIRATORY SYSTEM

2. FUNCTIONAL ANATOMY OF THE RESPIRATORY SYSTEM • Respiratory System: • Pulmonary ventilation: movement of air into and out of the lungs so that gases there are continuously changed and refreshed (commonly called breathing) • External respiration: movement of oxygen from the lungs to the blood and of carbon dioxide from the blood to the lungs • Circulatory System: • Transport of respiratory gases: • Transport of oxygen from the lungs to the tissue cells of the body • Transport of carbon dioxide from the tissue cells to the lungs • Accomplished by the cardiovascular system using blood as the transporting fluid • Internal respiration: movement of oxygen from blood to the tissue cells and of carbon dioxide from tissue cells to blood

3. FUNCTIONAL ANATOMY OF THE RESPIRATORY SYSTEM • Respiratory and circulatory systems are closely coupled, and if either system fails, the body’s cells begin to die from oxygen starvation • Because it moves air, the respiratory system is also involved with the sense of smell and with speech

4. RESPIRATORY ORGANS • The respiratory system includes: • Nose • Nasal cavity • Pharynx • Larynx • Trachea • Bronchi • Bronchioles • Lungs • Alveoli

5. RESPIRATORY SYSTEM • Two Zones: • Conducting: • Includes all the passageways that provide rigid conduits for air to reach the gas exchange locations • Cleanses, humidifies, and warms incoming air • Respiratory: • Actual site of gas exchange, is composed of the respiratory bronchioles, alveolar ducts, and alveoli • All microscopic structures

6. RESPIRATORY ORGANS

7. EXTERNAL NOSE

8. NOSE • The nose is divided into the external nose, which is formed by hyaline cartilage and bones of the skull, and the nasal cavity, which is entirely within the skull

9. INTERNAL NASAL CAVITY • Divided by a midline nasal septum • Anteriorly cartilage • Posteriorly vomer and ethmoid bone • Continuous posteriorly with the nasal portion of the pharynx through the posterior nasal apertures (internal nares) • Roof of the nasal cavity is formed by the ethmoid and sphenoid bones of the skull • Floor is formed by the palate, which separates the nasal cavity from the oral cavity • Anterior: maxillary processes and palatine bone • Posterior: muscular and soft

10. INTERNAL NASAL CAVITYVESTIBULE • The part of the nasal cavity just superior to the nostrils • Lined with skin containing sebaceous and sweat glands and numerous hair follicles • Hairs (vibrissae) filter coarse particles (dust, pollen) from inspired air

11. INTERNAL NASAL CAVITYTWO TYPES OF MUCOSA • Olfactory: • Lines the slitlike superior region • Contains smell receptors • Respiratory: • Mucous glands: secrete mucus • Serous glands: secrete a watery fluid containing enzymes • Epithelial cells: secrete defensins (natural antibiotics that help get rid of invading microbes) • The sticky mucus traps inspired dust, bacteria, and other debris, while lysozyme attacks and destroys bacteria chemically • High water content of the mucus film acts to humidify the inhaled air

12. INTERNAL NASAL CAVITYRESPIRATORY MUCOSA • Ciliated cells create a gentle current that moves the sheet of contaminated mucus posteriorly toward the throat, where it is swallowed and digested by stomach juices • Cold air causes them to become sluggish • Mucus accumulates and dribbles out the nostrils • Richly supplied with sensory nerve endings: • Contact with irritating particles triggers a sneeze reflex—forcing air outward in a violent burst

13. INTERNAL NASAL CAVITYRESPIRATORY MUCOSA • Rich plexuses of capillaries and thin-walled veins underlie the nasal epithelium and warm incoming air as it flows across the mucosal surface

14. INTERNAL NASAL CAVITY • Protruding medially from each lateral wall of the nasal cavity are three curved scroll-like mucosa-covered projections: increase the mucosal surface area exposed to the air and enhance air turbulence in the cavity • Superior conchae • Middle conchae • Inferior conchae • Groove inferior to each concha is a meatus

15. THE NOSE AND PARANASAL SINUSES • The nose provides a resonance chamber for speech • The nasal cavity is surrounded by paranasal sinuses within the frontal, maxillary, sphenoid, and ethmoid bones that serve to lighten the skull, warm and moisten air, and produce mucus which drains into the nasal cavity • The suctioning effect created by nose blowing helps drain the sinuses

16. HOMEOSTATIC IMBALANCE • Rhinitis: inflammation of the nasal mucosa accompanied by excessive mucus production, nasal congestion, and postnasal drip • Caused by cold viruses, streptococcal bacteria, and various allergens • Sinusitis: inflamed sinuses • Since the nasal mucosa is continuous with the sinuses infections can easily spread to the sinuses • Sinus headache: when the passageways connecting the sinuses to the nasal cavity are blocked with mucus or infectious material, the air in the sinus cavities is absorbed resulting in a partial vacuum (localized over the inflamed areas)

17. THE PHARYNX • The pharynx connects the nasal cavity and mouth superiorly to the larynx and esophagus inferiorly • Commonly called the throat • Muscular pharynx is composed of skeletal muscle

18. Nasopharynx • Serves as only an air passageway • During swallowing, the soft palate and its pendulous (hanging loosely) uvula move superiorly, an action that closes off the nasopharynx and prevents food from entering the nasal cavity • Contains the pharyngeal tonsil (adenoids), which traps and destroys airborne pathogens

19. HOMEOSTATIC IMBALANCE • Infected and swollen adenoids (pharyngeal tonsils) block air passage in the nasopharynx, making it necessary to breathe through the mouth • Air is not properly moistened, warmed, or filtered before reaching the lungs

20. HOMEOSTATIC IMBALANCE • The pharyngotympanic (auditory) tubes, which drain the middle ear cavities and allow ear pressure to equalize with atmospheric pressure, open into the lateral walls of the nasopharynx • A ridge of pharyngeal mucosa, referred to as a tubal tonsil, arches over each of these openings • Help protect the middle ear against infections likely to spread from the nasopharynx • The pharyngeal tonsil also plays this protective role

21. NASOPHARYNX

22. OROPHARYNX • Is an air and food passageway that extends inferiorly from the level of the soft palate to the epiglottis • Air and food mix • Both swallowed food and inhaled air pass through • Epithelium is adapted for increased frictional and greater chemical trauma accompanying food passage • Two kinds of tonsils lie embedded in the mucosa: • Paired palatine tonsils lie in the lateral walls • Lingual tonsil covers the base of the tongue

23. LARYNGOPHARYNX • Is an air and food passageway that lies directly posterior to the epiglottis, extends to the larynx, and is continuous inferiorly with the esophagus • The esophagus conducts food and fluids to the stomach • Air enters the larynx anteriorly • During swallowing, food has the “right of way”, and air passage temporarily stops

25. MIDSAGITAL SECTION OF THE HEAD AND NECK

26. UPPER RESPIRATORY TRACT

27. THE LARYNXBASIC ANATOMY • The larynx (or voice box) attaches superiorly to the hyoid bone, opening into the laryngopharynx, and attaches inferiorly to the trachea • From 4th to 6th vertebra • Three functions: • Provide an open airway • Switching mechanism to route air and food into the proper channels • Because it houses the vocal cords. The 3rd function is voice production

28. THE LARYNX • The larynx consists of hyaline cartilages: • Thyroid:shield-shaped • Midline laryngeal prominence (Adam’s Apple) • Cricoid: ring shaped • Paired arytenoid, corniculate, and cuneiform • Epiglottis, which is elastic cartilage • Covered by mucosa-containing taste buds

29. LARYNX

30. POSTERIOR ASPECT OF LARYNX

31. CARTILAGINOUS FRAMEWORK OF LARYNX • During swallowing, the larynx is pulled superiorly and the epiglottis tips to cover the laryngeal inlet

32. VOCAL CORDS • Vocal ligaments attach the arytenoid cartilages to the thyroid cartilage • These ligaments composed largely of elastic fibers form the core of mucosal folds, called the vocal folds (true vocal cords) • Which vibrate as air passes over them to produce sound • Superior to the vocal cords are the false vocal cords • No part in sound production but help to close the glottis when we swallow

33. VOCAL CORDS

34. VOCAL CORDS • Below the vocal folds the epithelium is a pseudostratified ciliated columnar type that acts as a dust filter • The power stroke of its cilia is directed upward toward the pharynx so that mucus is continually moved away from the lungs • We help to move mucus up and out of the larynx when we “clear our throats”

35. VOICE PRODUCTION • Voice production involves the intermittent release of expired air and the opening and closing of the glottis • The length of the true vocal cords and the size of the glottis change with the action of the intrinsic laryngeal muscles that clothe the cartilage • As the length and tension of the cords change, the pitch (depends on the frequency and loudness: height of wave) of the sound varies • The tenser the cords, the faster they vibrate and the higher the pitch • (b) the glottis is wide when we produce deep tones and narrows to a slit for high-pitched sounds • Male larynx enlarges during puberty • Vocal cords become longer and thicker causing them to vibrate slower (voice becomes deeper)

36. VOICE PRODUCTION • Loudness of the voice depends on the force with which the airstream rushes across the vocal cords: • The greater the force, the stronger the vibration and the louder the sound • The power source for creating the airstream is the muscles of the chest, abdomen, and back • Vocal folds actually produce buzzing sounds • The perceived quality of the voice depends on the coordinated activity of many structures above the glottis • The entire length of the pharynx acts as a resonating chamber, to amplify and enhance the sound quality • Oral, nasal, and sinus cavities also contribute to vocal resonance • Good enunciation depends on the shaping of sound into recognizable consonants and vowels by muscles in the pharynx, tongue, soft palate, and lips

37. HOMEOSTATIC IMBALANCE • Laryngitis • Inflammation of the vocal folds • Vocal folds swell, interfering with their vibrations • Produces a change in the voice tone, hoarseness, or in severe cases inability to speak above a whisper

38. THE LARYNX • The vocal folds and the medial space between them are called the glottis • Under certain conditions, the vocal folds act as a sphincter that prevents air passage • Valsalva’s maneuver is a behavior in which the glottis closes to prevent exhalation and the abdominal muscles contract, causing intra-abdominal pressure to rise • Defecation: helps empty the rectum and can also stabilize the body trunk when one lifts a heavy load

40. THE TRACHEA • The trachea, or windpipe, descends from the larynx through the neck into the mediastinum, where it terminates by dividing into the two primary bronchi at midthorax • Cilia continually propel debris-laden mucus toward the pharynx

41. Cross-sectional view of the trachea, illustrating its relationship to the esophagus and the position of the supporting cartilage rings

42. TRACHEA • 16-20 C-shaped cartilage rings: • Prevents the trachea from collapsing despite the pressure changes in breathing

43. HOMEOSTATIC IMBALANCE • Smoking inhibits and ultimately destroys cilia, after which coughing is the only means of preventing mucus from accumulating in the lungs • For this reason, smokers with respiratory congestion should avoid medications that inhibit the cough reflex

44. HOMEOSTATIC IMBALANCE • Tracheal obstruction is life threatening • Heimlich maneuver, a procedure in which air in the victim’s lungs is used to “pop out”, or expel, an obstructing piece of food • Cracked ribs are a distinct possibility when done incorrectly

45. BRONCHIAL TREEBRONCHI and SUBDIVISIONS • Site where conducting zone structures give way to respiratory zone structures

46. THE BRONCHIAL TREE • The conducting zone consists of right and left primary bronchi that enter each lung and diverge into secondary bronchi that serve each lobe of the lungs • The right primary bronchus is wider, shorter, and more vertical than the left and is the more common site for an inhaled foreign object to become lodged • By the time incoming air reaches the bronchi, it is warm, cleansed of most impurities, and saturated with water vapor

47. Conducting Zone Structures • Once inside the lungs, each primary bronchus subdivides into secondary (lobar) bronchi—three on the right and two on the left—each supplying one lung lobe • Secondary bronchi branch into several orders of smaller tertiary bronchi, which ultimately branch into bronchioles • Cilia are sparse, and mucus-producing cells are absent in the bronchioles • Thus, most airborne debris found at or below the level of the bronchioles is removed by macrophages in the alveoli • Amount of smooth muscle in the walls increases as the passageways become smaller • A complete layer of circular smooth muscle in the bronchioles and the lack of supporting cartilage (which would hinder constriction) allows the bronchioles to provide substantial resistance to air passage under certain conditions

48. CONDUCTING RESPIRATORY PASSAGES

49. THE BRONCHIAL TREERESPIRATORY TREE • The respiratory zone begins as the terminal bronchioles feed into respiratory bronchiolesthat terminate in alveolar ducts within clusters of alveolar sacs, which consist of alveoli • Approximately 300 million gas-filled alveoli in the lungs account for most of the lung volume and provide a tremendous surface area for gas exchange

50. RESPIRATORY ZONE STRUCTURES