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ANP1105 (101)
Chapter 22

ANP1105 Chapter 22: The Respiratory System (p. 801-816) Functional Anatomy of the Respiratory System

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Department
Anatomy and Physiology
Course
ANP1105
Professor
Jacqueline Carnegie
Semester
Winter

Description
Major function of respiratory system is to supply body with oxygen and dispose of CO2. To achieve this, four processes must happen called respiration: I. Pulmonary ventilation (breathing):Air is moved in & out of lungs (inspiration and expiration); gases are continually refreshed II. External respiration: oxygen diffuses from lungs to blood; CO2 diffuses from blood to lungs III. Transport of respiratory gases: Oxygen is transported from lungs to tissues of body; CO2 is transported from tissues of body to lungs. Uses blood as transporting fluid (cardiovascular system) IV. Internal respiration: oxygen diffuses from blood to tissue cells; CO2 diffuses from tissue cells to blood *Respiratory handles first two processes, CV (cardiovascular) handles last two processes Respiratory system consists of two zones: respiratory zone & conducting zone • Respiratory zone: actual site of gas exchange. Composed of bronchioles, alveolar ducts and alveoli (all microscopic) • Conducting zone (respiratory passageways): includes: nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles o also cleanses, humidifies and warms incoming air Nose: • functions: o provides an airway for respiration o moistens and warms entering air o filters and cleans inspired air o serves as resonating chamber for speech o houses olfactory (smell) receptors • structures are divided into external nose and internal nasal cavity External nose: • difference in shape and size due to differences in nasal cartilage • includes: o root: area between eyebrows o bridge o dorsum nasi: terminates in apex (tip of nose) o nostrils: external openings; bound by flared alae • skin covering nose is thin & contains many sebaceous glands • Pathway:Air enters nasal cavity via external nares (nostrils): divided by midline nasal septum (formed anteriorly by cartilage and posteriorly by bone).Air then goes via internal nares to nasopharynx. Nasal cavity: • Roof of nasal cavity (area between eyebrows) is formed from ethmoid and sphenoid bones • Floor of nasal cavity is formed by palate (anterior is hard; posterior is soft): separates nasal cavity from oral cavity below • Vibrissae: Hair follicles that filter coarse particles (ex: dust and pollen) from inspired air • Nasal cavity lined by two types of mucosa: olfactory mucosa and respiratory mucosa o Olfactory mucosa: contains receptors for smell o Respiratory mucosa: pseudostratified ciliated columnar epithelium with goblet cells; lamina propria has mucous & serous glands (1 L/day sticky mucus containing lysozyme: antibacterial enzyme)  Respiratory mucosa cilia move contaminated mucus posteriorly to throat where it is swallowed and digested  Cold air makes cilia sluggish and mucus accumulates = runny nose  Veins underlie the nasal epithelium and when inspired air is cold, the vein is engorged with blood. Due to the vein’s thin walls, they burst and nosebleeds occur. • Nasal conchae: o Mucus-covered projections protruding from the nasal cavity o Increase mucosal surface area exposed to air and enhance air turbulence in the cavity o Air must twist and turn to avoid the mucus, and large particles are not likely to pass through • nasal mucosa richly supplied with sensory nerves, so irritants trigger sneeze reflex Paranasal sinuses: • surround nasal cavity • located in frontal, sphenoid, ethmoid and maxillary bones • they lighten the skull, produce mucus & warm and moisten air • nasal mucosa is continuous with sinus mucosa increasing spread of infection • sinus headache: passageways connecting sinuses to nasal cavity blocked > air in sinus absorbed > partial vacuum Pharynx: • commonly called the throat: common pathway for food and air • extends 13 cm, composed of skeletal muscle; mucosal lining varies • divided into three regions: nasopharynx, oropharynx and laryngopharynx Nasopharynx: • above soft palate & below sphenoid bone • serves only as an air passageway • Swallowing: the soft palate and its uvula move forward and close off the nasopharynx, preventing food from entering the nasal cavity • Nasopharynx is continuous with nasal cavity, so pseudostratified ciliated epithelium takes over the job of propelling mucus where the nasal mucosa leaves off • Pharyngeal tonsil: traps and destroys pathogens entering nasopharynx by air • Pharyngotympanic (auditory) tubes: drain the middle ear cavities and allow middle ear pressure to equalize with atmospheric pressure o Ridge of pharyngeal mucosa constitutes the tubal tonsil which helps protect the middle ear against infections likely to spread from the nasopharynx Oropharynx: • Isthmus of the fauces connect oral cavity to oropharynx • Extends from soft palate to epiglottis, so both swallowed food and air pass through • As nasopharynx blends into oropharynx, the epithelium changes from pseudostratified columnar to a more protective stratified squamous: accomadates the increased friction and chemical trauma accompanying food passage • Paired palatine tonsils + lingual tonsil Laryngopharynx: • Passageway for food and air • Lined with stratified squamous epithelium • Extends from epiglottis to larynx where respiratory and digestive pathways diverge (go separate ways) • During swallowing, food has “right of way” and air passage stops Larynx (voice box): • Extends 5 cm from 3 -6 cervical vertebra • Attaches to hyoid bone (above) and continuous with trachea (below) • 3 functions: o Produce an open airway o Act as a switching mechanism to route air and food into proper channels o Voice production: houses vocal cords • 9 cartilages connected by membranes and ligaments o Except for epiglottis, all nine are cartilaginous • Thyroid cartilage: formed by fusion of two cartilage plates o Adam’s apple marks the fusion point o Larger in males than females because male sex hormones stimulate its growth during puberty • Arytenoid cartilages (2): pyramid-shaped which anchor the vocal folds • Epiglottis: o 9 cartilage. o Flexible o Composed of elastic cartilage o Covered by taste-bud mucosa o Anchors to anterior rim of thyroid cartilage & extends up to base of tongue • True vocal cords: white (lack blood vessels); vibrate, producing sounds as air ruses up from the lungs o Opening between the vocal cords is called glottis • False vocal cords:
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