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Respiration: Anatomy • Respiration = process of gas exchange between the organism and environment. Oxygen taken in during inspiration; waste products (e.g., CO2) expelled during expiration. • 1. RESPIRATORY PASSAGE • Composed of nasal and oral cavities, pharynx, larynx, trachea, and bronchi • Functions: trachea Trachea • For a simple video of how respiration works, click on the button from argosymedical.com http://science.nationalgeographic.com/science/health-and-human-body/human-body – A. Larynx: specialized valvular mechanism; can open or close the air passageway. – Biological function: • Protective device Google “Vocal folds and cough” • Thoracic fixation: needed to increase abdominal pressure to evacuate visceral contents. – When is fixation used? – B. Trachea: muscular tube • extends from larynx to bronchi • 11 to 12 cm in length and between 2-2.5 cm in diameter • composed of 16 to 20 horseshoe-shaped rings of hyaline cartilage – Each ring separated by sm. space of fibroelastic membrane. – Each ring is incomplete posteriorly where trachea lies in contact with esophagus-fibrous tissue and muscle are in space between ends – Cartilaginous structure allows for rigidity to prevent collapse, while posterior structure (muscle & membranes) provide flexibility & mobility that permit it to be stretched (e.g., during inhalation), twisted, or compressed. Trachea cont. http://www.youtube.com/watch?v=sU_8juD3YzQ http://video.google.com/videosearch?q=cilia&hl=en&emb=0#q=human% 20respiration&hl=en&emb=0&start=20 – Functions: » How are these accomplished? » Hyaline rings stiffen structure to help keep it open. » Trachea lined with ciliated epithelial mucous membrane, secretes mucous to moisten incoming air; cilia are in constant motion, beat @ 10X-20X per second, at first downward, then slowly upward – Clinical note: One of major causes of lung infection is reduced ciliary action. Normally the mucous blanket lining trachea is propelled toward larynx at rate of 5mm per minute. Smoke from a single cigarette can cause cilia to be non-motile for several hours. At the same time cigarette smoke stimulates mucus secretion. – Cilia begin to repair and regenerate only 3 days after smoking ceases, although the complete process takes @ 7 years. Some damage can be permanent. – CLINICAL NOTE: An emergency operation called tracheostomy (tome = cutting) is sometimes performed because of such things as obstruction of upper airway due to inflammatory disease or food lodged in larynx. Incision is made in anterior neck, usually between 2nd and 3rd tracheal cartilages. Opening into trachea called tracheostoma (stoma = mouth). See next slide – C. Bronchi: tubes extending from trachea to lungs where they arborize (branch) to form bronchial tree. – Bronchi divided into three groups: • 1. main or main stem bronchi • 2. lobar or secondary bronchi (supply lobes of lungs) • 3. segmental or tertiary bronchi (supply segments of lobes) • 1. Main bronchi: is larger than • Structure similar to trachea (e.g., imperfect cartilaginous rings, lined with ciliated epithelial lining). Right bronchus divides into three secondary bronchi (one for each lobe) and into 10 tertiary bronchi. Left divides into 2 secondary and then 8 tertiary. • 2. Bronchioles: In adult there are about 24 generations of divisions in the bronchial tree. Final division gives rise to bronchioles, tubes are 1 mm or less in diameter. Repeated divisions of bronchioles give rise to terminal bronchioles which communicate with alveolar ducts, which open into minute air sacs. • 3. Alveoli: The terminal bronchioles and air sacs are pitted with around 7,000,000 small depressions call alveoli. The alveolar wall is invested with capillary network (about 1,000 miles of capillaries—e.g., from Dayton, OH to Orlando). Capillaries separated from air by barrier of less than 1/3 diameter of red blood cell. Total alveolar area in contact with capillaries is @ size of tennis court. Thin barrier and immense area facilitate rapid exchange of oxygen and carbon dioxide. • Alveoli cont. • Alveoli contain Type I (simple squamous epithelium) cells and Type II cells (produce surfactant). Lining also contains Phagocytic cells, also called alveolar macrophages (ingest dust, bacteria, and other debris--are also injured by smoke). • Simple squamous epithelial cells permit: • Exchange of gases between the air in the lungs and the blood in the capillaries occurs across the walls of the alveolar ducts and alveoli. • Surfactant: any substance that reduces the surface tension. See next slide. • Alveoli properties: Epithelial lining keeps tissue moist thru secretions. Surface tension exists due to attraction of molecules for one another. The force causes liquid lining to behave like stretched elastic, it tries to shorten and resist further stretching. • Surface tension accounts for tendency of alveoli to collapse, and this tendency to collapse is responsible for 2/3 of elasticity of lungs. The Type II cells produce surfactant which acts like detergent, decreasing surface tension. Surfactant proteins have also been found to be part of the defensive mechanism that helps fight pathogens (infections) and inflammation.* • CLINICAL NOTE: Consequences of insufficient surfactant production is respiratory distress syn. or infant respiratory distress syndrome (formerly called hyaline membrane disease) which affects premature babies. Type II cells are too immature to produce enough surfactant in these cases. Infant able to inspire only by exhaustive efforts due to lung resistance to expansion. Can result in respiratory failure, lung collapse and death. Medical Tx: administer cortisol to pregnant women OR surfactant replacement tx. FYI – D. Lungs www.innerbody.com (cardiovascular system; animations) – Biological Function: breathing for life, protection for heart and for removal of wastes and toxins.+ – located in thoracic cavity (chest). • Thorax houses lungs, heart, great blood vessels, esophagus. – 2 irregularly cone-shaped structures--composed of spongy, porous, highly elastic material. – When handled in a cadaver, sound like crumpling tissue paper (due to presence of air within the alveoli). – White in color at birth, become progressively darker.* See next slide – R lung larger, but shorter and broader (due to liver occupying R abdominal cavity forcing dome of diaphragm higher on R side). Heart occupies L side of thorax, thus smaller L lung lobe. – Contains few muscle fibers. Thus lung tissue is passive, cannot exert force except by elastic properties. 1/4-1/3 of elasticity of lung due to lung tissue properties. Remainder of elasticity due to alveoli. Normal lung Filter before and after particulate testing, Italy cancer emphysema Non-smoker, smoker – Each day you breathe about 25,000 times, and by the time you're 70 years old, you'll have taken at least 600 million breaths. * – The Pleurae: inner surface of thoracic cavity, thoracic surface of diaphragm, & mediastinum (space between R and L lungs; median partition of thoracic cavity) are lined with a membrane called parietal or costal pleura. The visceral pleura lines the lungs. SEE NEXT SLIDE • 2 types of pleurae 1. costal (parietal) 2. Visceral NOTE: liquid located between pleurae to form bond. • FUNCTION: (a) provides friction-free lung and thoracic surfaces. The two moist surfaces glide on one another with every breathing cycle. The R and L pleural sacs are completely separated. The mediastinum between them contains heart, blood vessels, and esophagus. Blue = costal; pink = visceral pleura CLINICAL NOTE: pneumothorax-puncture of one lung, resulting in collapse. Done medically for Tx of tuberculosis or similar illnesses. Collapsed lung benefits from rest received. After closing the opening, the lung slowly expands. • Pleurae mechanics: Lungs have tendency to collapse and pull away from thoracic walls due to: – (a) inherent elasticity of lung tissue+ (b) surface tension in fluid lining of alveoli produces tendency to collapse. • -Through pleural linkage (of pleural membranes-negative pressure created in intrapleural spaces by absorption of gases and fluids and bounds two pleurae by intrapleural fluid pressure) to thoracic walls, lung surfaces are held tightly in contact with inner surface of thoracic walls. • Inhalation: lungs expand due to chest cavity enlarging; during exhalation elasticity of lungs takes over, creating increased recoil, and lungs return to unexpanded state. Using your knowledge about pleural mechanisms, what would be the symptoms of the individual who has lungs as shown on the right? • www.getbodysmart.com; look at tutorials on respiration, trachea through lungs, and take quizzes on these sections. • Please go through the video presentation as shown below and as listed on Webcourses in the file Respiration Website. • http://lgfl.skoool.co.uk/content/keystage4/biology/ pc/lessons/uk_ks4_breathing_and_respiration/hframe-ie.htm Respiratory Framework • Principle framework: – – – – – spinal or vertebral column Ribs Pectoral girdle Sternum Pelvic girdle http://www.anatomy.wright.edu/QTVR/index.html – A. Spinal column: 32-33 vertebrae joined together by intervertebral cartilage and ligaments (fibrous connective tissue which connects bones or holds organs in place). – Types of vertebrae: often identified by letter (type) & number (position) C5, L4 • • • • 7 cervical (cervix = neck) 12 thoracic (chest) 5 lumbar (loin) 5 sacral (sacred)--fit together, appear to be one bone called sacrum • 3-4 coccygeal (cuckoo--suppose to resemble the beak of a cuckoo)-vestigial (sm. degenerate or incompletely developed structure which was more fully dev. in previous stage of species)-usually thought of as individual structure called coccyx. • See next slide • www.apparelyzed.com/spinalcord.html • Myotomes and disability FYI • Myotomes - Relationship between the spinal nerve & muscle • Dermatomes - Relationship between the spinal nerve & skin. • Each muscle in the body is supplied by a particular level or segment of the spinal cord and by its corresponding spinal nerve. The muscle, and its nerve make up a myotome. This is approximately the same for every person and are as follows: C3,4 and 5 supply the diaphragm (the large muscle between the chest and the belly that we use to breath). C5 also supplies the shoulder muscles and the muscle that we use to bend our elbow . C6 is for bending the wrist back. C7 is for straightening the elbow. C8 bends the fingers. T1 spreads the fingers. T1 –T12 supplies the chest wall & abdominal muscles. L2 bends the hip. L3 straightens the knee. L4 pulls the foot up. L5 wiggles the toes. S1 pulls the foot down. S3,4 and 5 supply the bladder. bowel and sex organs and the anal and other pelvic muscles. • • • • • • • • • • • • • – Types of vertebrae: • cervical vertebrae: – Atlas (C1) = skull rests on atlas (Greek mythology giant Atlas had to bear the wt. of sky-punished by Zeus)-shaped like ring--anterior and posterior tubercles=imp. landmarks in radiographic exam of sp. mech. – Axis (C2) = forms pivot @ which altas and skull rotate--landmark dens (tooth) or odontoid (toothlike) process--is projecting cranially (see next slide) – C7 = conspicuous spinous process which can usually be palpated at base of neck • thoracic vertebrae: provide pts. of attachment for ribs--increase in size from T1 to T12 • lumbar = very lg.--Wt. bearing function – Spinal curves: discs which are between vertebrae in the cervical and lumbar regions are thicker anteriorly than posteriorly, creating concave curvature of the spine in those areas. In thoracic region, discs are same thickness, however, bodies of vertebrae are slightly thinner in front than in back creating a convex curvature. • CLINICAL NOTE: Abnormal curvatures of spine – kyphosis: hunchback--increased convex curvature in thoracic verte.--sometimes caused by tuberculosis in vertebral bodies, bodies become eroded, weakened, and distorted by wt. of body. Poor posture and m. imbalance may also be contributing factors. Kyphosis can inhibit rib cage movement and reduce pulmonary compliance. – lordosis: swayback--caused by TB, poor posture, or prolonged wearing of excessively high heels. – scoliosis: abnormal lateral curvature--caused by muscle imbalance, poor posture, diet, paralysis. • Respiratory framework cont. – B. Sternum or breastbone--3 parts: manubrium (handle), body, xiphoid process (sword) • manubrium: articulates with clavicle (collarbone) and with 1st costal cartilages of ribs – C. Ribs: The rib cage = 12 pair of ribs--ribs designated by numbers--First 7 ribs course obliquely downward from the vertebral column (in infant ribs are more horizontal). At their lowest pt., the osseous ribs give way to costal cartilages which course upward to articulate with the sternum. In old age, the cartilages ossify superficially, reducing the compliance of the rib cage.* – CLINICAL NOTE: extra ribs, esp. on C7, are not uncommon and may cause discomfort and pain. A rib on L1 may cause back problems. • Ribs cont. – First 7 ribs articulate with sternum = true ribs or vertebrosternal – Next 3 pairs (8, 9, 10) are connected indirectly with sternum by long costal cartilages = false ribs or vertebrochondral ribs (chrondral = pertaining to cartilage) – Last 2 have vertebral attachments, but anterior extremeties are free = vertebral or floating ribs – Movements in breathing: During inhalation, the dimensions of the thoracic cavity increases in 3 planes: vertically (diaphragm contracts), transverse (raising of curved ribs), anteroposterior (simultaneous forward and upward movement of sternum) – D. Pelvic girdle: hip bone (or coxal bone), sacrum and coccyx – Function for speech = abdominal wall muscles attach to hip bone and pelvis is "floor" for abdominal viscera. – CLINICAL NOTE: for most pts. with cerebral palsy, proper positioning of the pelvis is crucial to maintanence of breath support for speech. – E. Pectoral (breast) girdle: clavicle and scapula MUSCULATURE OF BREATHING MECHANISM • Muscles of inhalation are mainly in the thorax; muscles of exhalation primarily in abdomen. 1. Muscles of thorax: (A) diaphragm (B) external intercostals (C) internal intercostals (D) transversus thoracis (E) costal elevators, and (F) serratus posterior, superior, and inferior • A. Diaphragm: (means = partition, wall, barrier). It is the main muscle for breathing (inspiration). Separates thorax (lungs, heart, structures in mediastinum) from abdomen (filled with digestive tract). Thin but very strong Dome-shaped, like inverted bowl May be most important muscle in body next to heart. Unpaired muscle • • • • • • www.kidshealth.org/kid/body • Origin at xiphoid process of sternum, inner surface of ribs 7 - 12, upper lumbar vertebrae posteriorly. Fibers course upward and inward, inserting into central tendon. • When we inhale, the diaphragm moves downward toward the abdomen, and the rib muscles pull the ribs upward and outward, enlarging the chest cavity and pulling air in through the nose or mouth. • When we exhale, the diaphragm moves upward (relaxes), forcing the chest cavity to get smaller and pushing the gases in the lungs up and out of the nose and mouth. • Air pressure : • ACTION=when rim contracts, pulls diaphragm downward and slightly forward, thus increasing thorax in vertical direction. Contraction compresses abdominal contents. There may be expansion of abdominal wall-sometimes called abdominal or diaphragmatic breathing. Contraction also increases circumference of thoracic cavity through elevation of lower ribs. • B. External Intercostal muscles: • More prominent and stronger than internal intercostals • 11 in number • Originate at lower surface of a rib; course downward and laterally; terminate near chondro-osseous union of ribs and cartilage • ACTIONS= elevate rib below, thus increasing the anteroposterior and transverse dimensions, during inspiration. • They tense rib interspaces, preventing them from being sucked inward during inspiration. • Are inactive during expiration on quiet breathing, however, are active during forced exhalation. • Conclusion: They are active mainly during inspiration. • / • • • • • • • C. Internal Intercostal muscles lie deep to external 11 Course from anterior limits of intercostal space (immediately lateral to the sternum) to angle of rib posteriorly (pt. where rib abruptly changes direction). Originate on the superior portion of a rib; course medially; and insert on the next rib above. – This course is opposite to external intercostals. THUS, area lateral to vertebral column is devoid of internal intercostals and the area lateral to the sternum is devoid of external intercostals. ACTION= – Intercartilaginous portion = inspiratory in function (elevating ribs, especially during forced inspiration). – Interosseous portion= pull ribs downward and stiffen rib interspaces--aids in exhalation--probably active during speech production. CONCLUSION: Aid prolonged and forced exhalation Note the lack of external intercostals near the sternum and the termination of the internal intercostals (they never reach the vertebral column) Which arrows are pointing to the ending points or terminations of the internal intercostals? Which are pointing to the end point of the external intercostals? – Summary of intercostal action • Intercostal muscles are major contributors to inspiration. One can still produce an adequate level of pulmonary ventilation with just intercostal muscles, if the diaphragm is paralyzed. • In general, they produce rib movements during inhalation, and contribute to the rigidity of the thoracic wall by preventing intercostal spaces from being pulled in and out during breathing. Also help control the amount of space between ribs; and they couple ribs, one to another, so that movement of one rib will influence position of adjacent ribs. • Both are active during non-passive/active expiration (forced = external; prolonged = internal) • D. Transversus Thoracis muscles (deep to intercostals) • Located on inner surface of anterior thoracic wall. Originate from posterior body of sternum & post. surface of xiphoid process & post. surfaces of chrondral portions of ribs 5 - 7. Insert into lower borders and inner surfaces of ribs 2-6. • ACTION: Depress ribs to aid in exhalation • E. Costal Elevators: 12 on ea. side--arise from C7 and upper 11 thoracic vertebrae-course obliquely downward and laterally--insert at angle of rib--ACTION: elevate ribs during inhalation (see below) • F. Serratus posterior superior: Arises from spinous process of C7 & T1,2--courses downward & obliquely--inserts on ribs 2-5-ACTION: may elevate ribs • G. Serratus posterior inferior: Arises from spinous process of T11& T12, & L1,2,3--courses upward & obliquely--inserts on ribs 8-12-ACTION: probably exerts downward press. on lower ribs during forced exhalation. • 2. Muscles of neck: • Sternocleidomastoid and scalenes [means “uneven”] • A. Sternocleidomastoid • originates from 2 heads— – sternal head= anterior surface of manubrium of sternum; – clavicular head= superior surface of sternal end of clavicle--fibers course upward, 2 heads unite. – Inserts as single m. into mastoid process of temporal bone – ACTION: unilateral contraction= draws side of head toward shoulder and rotates it. Bilateral contraction tends to flex neck toward thorax. When head in fixed position, muscle may raise sternum and clavicle to assist in inhalation (increases anteroposterior dimension of thorax). • B. Scalene muscles: • Origin= transverse processes of cervical vertebrae to insertion on two uppermost ribs • ACTION: supplementary m. of inhalation-raise first two ribs. • CLINICAL NOTE: excessive use of the neck musculature is freq. in patients with chronic lung disease. Pronounced use of upper thoracic and neck muscular during inhalation is termed clavicular breathing, and usually regarded as inefficient and undesirable. May be used as compensation in patients. with paralysis of principle breathing muscles. • 3. Abdominal muscles are flexors of the vertebral column & enclose and lend support to abdominal contents. • RESPIRATORY FUNCTION = may limit the depth of inspiration, and are active in forced exhalation. • A. External oblique: most superficial of abdominal muscles • Origin = exterior surfaces of ribs 5-12. Course medially and downward. Insert on iliac crest. • Largest and strongest of abdominal muscles. • ACTION: compresses abdominal contents, thus raises intra-abdominal & intrathoracic pressure. Used for emesis, defecation, and forced expiration. • B. Internal oblique: lie just deep to external oblique--form middle layer of abdominal musculature. Course just opposite to external oblique. Arise from iliac crest, spread over lateral wall of abdomen, insert into linea (linea = stripe or streak) alba (white) (fibrous band extending from xiphoid process to pubic symphysis). • ACTION: compress abdominal contents, assists in expelling abdominal contents and in forced exhalation. • C. Transversus Abdominis: deepest abdominal m.--as name implies, course is horizontal. Arise on inner surfaces of ribs 6 12, and from iliac crest, and inguinal (pertaining to groin) ligament. Insert into abdominal aponeurosis (broad sheet of connective tissue, connecting m. to bone). ACTION: compresses abdominal contents--may be most effective m. for forced exhalation. • D. Torso muscles (upper limb & back)