Respiratory System Lecture Notes PDF

RESPIRATORY SYSTEM EXCHANGE OF GASES  OVERVIEW OF RESPIRATORY SYSTEM Components – upper respiratory tract: nasal cavity to pharynx – lower respiratory tract: larynx to lungs Functional Zones – conducting zone: transports air – respiratory zone: si...

RESPIRATORY SYSTEM EXCHANGE OF GASES  OVERVIEW OF RESPIRATORY SYSTEM Components – upper respiratory tract: nasal cavity to pharynx – lower respiratory tract: larynx to lungs Functional Zones – conducting zone: transports air – respiratory zone: site of gas exchange FUNCTIONS OF THE RESPIRATORY SYSTEM gas exchange external respiration: exchange between air and blood internal respiration: exchange between blood and cells gas conditioning – gas is warmed – cleansed – moistened – this is done before gas reaches gas exchange zone FUNCTIONS OF THE RESPIRATORY SYSTEM sound production – sound is produced as air passes through the larynx olfaction – nasal mucosa is lined with olfactory cells UPPER RESPIRATORY TRACT  NOSE AND NASAL CAVITY conducts air external anatomy – nasal bones: superiorly – dorsum nasi: top of nose-inferior to bridge – paired nostrils – apex: tip of nose  NOSE AND NASAL CAVITY Made up of – Bone – Hyaline cartilage – Dense connective tissue INTERNAL STRUCTURES OF NASAL CAVITY nasal cavity: continuous with nasopharynx through internal nares vestibule: anterior region near nostril INTERNAL STRUCTURES OF NASAL CAVITY vibrissae: coarse hairs to trap particles in the air olfactory epithelium: superior lining of INTERNAL STRUCTURES OF NASAL CAVITY nasal septum – divides nasal cavity into R and L halves – septal nasal cartilage anteriorly – and vomer and perpendicular plate of ethmoid bone posteriorly INTERNAL STRUCTURES OF NASAL CAVITY conchae: along lateral walls of nasal cavity – 3 paired projections superior, middle, and inferior – divide nasal cavity into air passages called meatuses meatus force air to become turbulent also leads to moistening and warming  PARANASAL SINUSES contained within 4 skull bones: frontal, ethmoid, sphenoid, maxilla decrease weight of skull warm and moisten air connected to nasal cavity by  PHARYNX (THROAT) shared by respiratory and digestive systems begins behind nasal and oral cavities ends at splitting of larynx and esophagus Has three regions: nasopharynx, oropharynx and laryngopharynx  Choanae: entry of nasal cavity into nasopharynx only used by respiratory system soft palate (muscle) and uvula – prevents swallowed material from entering nasal cavity  Opening of auditory tubes – connect nasopharynx with middle ear – allows for pressure equilibration pharyngeal tonsil (adenoids) – on posterior surface – Traps and OROPHARYN X behind oral cavity used by respiratory and digestive system fauces: entry point of oral cavity into oropharynx palatine tonsil: found on lateral wall lingual tonsil: at base of tongue Both tonsils trap pathogens in food  LARYNGOPHARYNX extend from hyoid bone and ends at larynx and esophagus ends at cricoid cartilage of larynx allow for passage of food and air LOWER RESPIRATORY TRACT  LARYNX called the voice box sits between laryngopharynx and trachea functions – conduct air into lower respiratory tract – produce sound  CARTILAGES OF THE LARYNX thyroid cartilage – forms anterior and lateral wall – hyaline cartilage – thyrohyoid membrane attaches thyroid cartilage to hyoid bone – V-shaped laryngeal prominence “adam’s apple”  CARTILAGES OF THE LARYNX cricoid cartilage – sits below thyroid cartilage – hyaline cartilage – connects to trachea inferiorly – cricothyroid ligament: connects cricoid cartilage to thyroid cartilage Figure 25.4  CARTILAGES OF THE LARYNX epiglottis – elastic cartilage – attaches to thyroid cartilage but projects superiorly into pharynx – covers larynx during swallowing larynx actually raises up  CARTILAGES OF THE LARYNX arytenoid cartilage – paired hyaline cartilage – rest on top/posterior border of cricoid cartilage corniculate cartilage – paired hyaline cartilage – attaches to superior  CARTILAGES OF THE LARYNX cuneiform cartilage – paired hyaline cartilage – not directly attached to any other cartilage  SOUND PRODUCTION IN LARYNX Vocal cords – 2 pairs of ligaments extend from thyroid cartilage to arytenoid cartilage – true vocal cords refers to the inferior pair of ligaments produces sound as passing air causes vibration  SOUND PRODUCTION IN LARYNX vestibular ligaments (False Vocal Cords) – protects true vocal cords – attached to both corniculate and arytenoid cartilages – Helps to close glottis during swallowing rima glottidis – opening between vocal folds glottis – rima glottidis plus  created as air passes through rima glottidis causes vibration of vocal cords to produce sound  Lateral cricoarytenoid muscle – adducts the vocal cords Posterior cricoarytenoid muscle – Abducts the vocal cords Oblique arytenoid muscles  EXTRINSIC MUSCLES OF THE LARYNX Thyrohyoid muscle – Elevates the larynx and depresses the hyoid bone during swallowing and speech Cricothyroid muscle – Helps in tensing the vocal cords  range – longer cords produce lower sounds as we get older, vocal cords lengthen to deepen our voice pitch – based on tension or tightness of cords can vary by using intrinsic laryngeal muscles loudness – depends on force of air passing through the rima glottidis loud sounds -caused by large quantities of rushing air soft sounds - caused by small quantities of air  TRACHEA (WINDPIPE) lies anterior to esophagus inferior to larynx superior to primary bronchi  TRACHEA (WINDPIPE) tracheal cartilages – 15-20 C-shaped hyaline cartilages – reinforce the trachea so it always stays opened  TRACHEA (WINDPIPE) anular ligaments – connect C-shaped cartilages together trachealis muscle – covers opened ends of C-shaped cartilages – moves into trachea during swallowing – Contraction and relaxation narrows or widens trachea to adjust for airflow such as when coughing  PRIMARY BRONCHI trachea splits into R and L primary bronchi at sternal angle project inferiorly and laterally towards each lung carina – inferiomost tracheal cartilage – separate primary bronchi at origin Right primary bronchus – shorter and wider and more vertical more foreign material gets lodged in it  BRONCHIAL TREE system of branched tubal passages that originate from primary bronchi conduct air into thinner and thinner tubes progressively divide throughout the lungs end in terminal bronchioles  BRONCHIAL TREE primary bronchus enters at hilus of lungs then branches into lobar (secondary) bronchi – 3 on right and 2 on left – Enter each lobe secondary then branches into tertiary branching may occur 9 to 12  BRONCHIAL TREE bronchioles when diameter is less than a 1 mm the tubes are called bronchioles terminal bronchioles bronchioles continue to branch before finally ending as terminal bronchioles (0.5mm dia) final segment in the conducting zone Structural Changes in BRONCHIAL TREE As successive branching occurs – cartilage rings are replaced by irregular plates of cartilage – No cartilage present at the level of the bronchioles – Mucosal cells change from PSCC to columnar to cuboidal – Cilia sparse and mucous cells absent in bronchioles – Smooth muscle increases  RESPIRATORY ZONE Respiratory bronchioles – terminal bronchioles branch to form respiratory bronchioles – further branching forms smaller respiratory bronchioles  RESPIRATORY ZONE alveolar ducts – small respiratory bronchioles divide into thin airways called alveolar ducts alveolar sacs – alveolar ducts Figure 25.9  RESPIRATORY ZONE alveoli – Outpockets on respiratory bronchioles and alveolar ducts – lungs contain 300-400 million alveoli total – Very thin walls – alveolar pores connect alveoli together allow for collateral ventilation  RESPIRATORY ZONE Alveoli – Macrophages: to clear pathogens – Type I cells: form the respiratory membrane – Type II cells: secrete surfactant which prevents alveoli from collapsing (reduces surface tension of water)  RESPIRATORY MEMBRANE consist of thin alveoloar wall and juxtaposed capillaries gases must cross this membrane for gas exchange to take place  LUNGS houses bronchial tree and respiratory zone 2 lungs separated by mediastinum Pleura – covers outer lung surface – visceral pleura: hugs lung – parietal pleura: lines chamber – pleural cavity: between visceral and parietal pleura – pleural fluid: secretions within  surfaces of the lung – costal surface: contacts thoracic wall – mediastinal: faces mediastinum  Base – concave shaped – rest inferiorly on diaphragm apex – superior region – hilum on the mediastinal surface site where bronchi, blood vessels, nerve enter or leave lung – root: refers to all structures that pass through the hilum  RIGHT VS LEFT LUNG Left lung is slightly smaller than the right lung because heart projects into left cavity  LEFT LUNG cardiac impression: medial surface indentation formed by heart cardiac notch: anterior indented region lobes – superior and inferior lobes – separated by oblique fissure Figure 25.12 Figure 25.12  RIGHT LUNG 3 lobes: superior, middle, and inferior fissures – horizontal fissure: separates superior and middle lobes – oblique fissure: separates middle and inferior lobes Figure 25.12  CLINICAL CONDITIONS Chronic Bronchitis: form of COPD in which cilia is immomobilized while goblet cells overproduce mucus. Stagnant mucus provide growth medium for bacteria leading to infections Asthma: narrowing of brochioles to restrict airflow Tubercolosis (TB): bacterial infection of lungs. Stimulates lungs to form fibrous nodules called tubercles. Progressive fibrosis affects recoil and CLINICAL CONDITIONS Pneumonia: caused by bacterial, viral or fungal (a) Normal infection of lower respiratory tract. Fluid and Triggers filling of lungs blood cells in alveoli with fluid and dead Alveolar walls thickened WBCs which affects gas by edema exchange (b) Pneumonia Emphysema: form of Confluent COPD. alveolar walls alveoli breakdown and lungs (c) Emphysema  CLINICAL CONDITIONS Lung cancers: most commonly caused by smoking Squamous-cell carcinoma: – Most common type – basal cells of bronchial epithelium multiply and PSCC transforms to stratified squamous type. – Dividing cells invade bronchial wall to cause lesions – Dense keratin appears in lung to replace functional respiratory tissue  CLINICAL CONDITIONS Adenocarcinoma: – originates in mucous glands of respiratory wall – Nearly as common as squamous cell carcinoma Small cell carcinoma – Originates in main bronchi but invades mediastinum and quickly metastasizes. FIG. 22.27 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Tumors (a) Healthy lung, mediastinal surface (b) Smoker's lung with carcinoma a: © The McGraw-Hill Companies/Dennis Strete, photographer; b: Biophoto Associates/Photo Researchers, Inc.