BSC2086 A&P II Exam #4 Study Guide 1 Lesson 13: The Respiratory System Part I An Introduction to the Respiratory System • Respiratory system supplies cells with O2 & removes produced CO2 • Oxygen (O2) o Obtained from the air by diffusion across delicate exchange surfaces of lungs o Carried to cells by the cardiovascular system – also returns carbon dioxide to the lungs • Cells produce energy for maintenance, growth, defense, & division o Use mechanisms that use O2 & produce CO2 Components of the Respiratory System • Five (5) Functions of the Respiratory System o Provides extensive gas exchange surface area between air & circulating blood o Moves air to and from exchange surfaces of lungs o Protects respiratory surfaces from outside environment o Produces sounds o Participates in olfactory sense • Respiratory system is divided into: o Upper Respiratory System (URS) – above the larynx o Lower Respiratory System (LRS) – below the larynx • Respiratory Tract o Conducting Portion: Nasal cavity terminal bronchioles Respiratory Mucosa: Lines conducting portion • Epithelial layerBSC2086 A&P II Exam #4 Study Guide 2 • Lamina Propria: Areolar layer URS – trachea & bronchi contain mucous glands – secrete onto epithelial surface LRS – contains smooth muscle cells that encircle lumen of bronchioles. o Respiratory Portion: Respiratory bronchioles alveoli Alveoli: Air-filled pockets where ALL gas exchange occurs • Respiratory Epithelium o For efficient gas exchange… Alveoli walls must be very thin (<1 µm) Surface area must be very great (~35x the surface area of the body) o Alveolar Epithelium: Lines exchange surfaces of alveoli Simple Squamous Epithelium: Flat epithelial cells forming a single layer • Thin enough Very delicate • Respiratory Defense System – removes particles & pathogens o Consists of a series of filtration mechanisms: Mucous cells & mucous glands – produce mucus that bathes exposed surfaces Cilia – sweep debris trapped in mucus toward the pharynx • Mucus escalator Filtration in nasal cavity removes large particles Alveolar macrophages engulf small particles that reach lungs Upper Respiratory Tract • Nose: Where air enters the respiratory system o Nasal Hairs: First particle filtration systemBSC2086 A&P II Exam #4 Study Guide 3 • Nasal Cavity: Provides sense of smell (olfaction) o Mucous secretions & tears clean and moisten nasal cavity o Warms & humidifies air entering respiratory system Breathing through mouth bypasses this important step • Pharynx: Chamber shared by digestive & respiratory systems o Extends from internal nares entrances to larynx & esophagus o Divided into three (3) parts: Nasopharynx: Superior portion of pharynx Oropharynx: Middle portion of pharynx Laryngopharynx: Inferior portion of pharynx o Air goes from pharynx to larynx • Larynx: A cartilaginous structure that surrounds the glottis – narrow opening connecting the pharynx to larynx o Cartilages of the larynx: Thyroid Cartilage – Anterior surface called laryngeal prominence (Adam’s Apple) Cricoid Cartilage Epiglottis o Cartilage Functions Thyroid & cricoid cartilages support and protect: • Glottis • Entrance to trachea During swallowing: • Larynx is elevated • Epiglottis folds back over glottis – prevents entry of food into tracheaBSC2086 A&P II Exam #4 Study Guide 4 o Ligaments of the larynx: Vestibular Ligaments: Lie within vestibular folds – protect vocal folds (delicate) Sound production – air passing through glottis • Vibrates vocal folds o Slender, short folds = higher pitch o Thicker, longer folds = lower pitch • Vocal Cords: Vocal folds involved with sound production • Produces sound waves o Varied by tension on vocal folds o Controlled by voluntary muscles Lower Respiratory System • Trachea (windpipe) o Extends from cricoid cartilage into mediastinum Then branches into right & left pulmonary bronchi o Tracheal Cartilages 15-20 tracheal cartilages strengthen & protect airway Discontinuous where trachea contacts esophagusBSC2086 A&P II Exam #4 Study Guide 5 C shaped – allows distortion of tracheal wall for food passage in esophagus Ends of each tracheal cartilage are connected by: • An elastic ligament • Trachealis Muscle – contraction reduces diameter o Normally regulated by sympathetic division o Sympathetic stimulation causes relaxation of muscle • Right & Left Primary Bronchi o Separated by the carina – internal ridge o Right Primary Bronchus Larger diameter than the left Descends at a steeper angle • Most foreign objects that enter the trachea enter the right primary bronchus • Lungs o Left & right lungs are in left & right pleural cavities o The base – inferior portion of each lung rests on superior surface of diaphragm o Lobes of the lungs Lungs have lobes separated by deep fissures Right lung has three (3) lobes Left lung has two (2) lobesBSC2086 A&P II Exam #4 Study Guide 6 o Bronchial Structure Primary bronchus branches to form secondary bronchi (lobar bronchi) One secondary bronchus goes to each lobe & branches to form tertiary bronchi (segmental bronchi) o The walls of primary, secondary, and tertiary bronchi Contain progressively less cartilage & more smooth muscle Increased smooth muscle tension affects airway constriction & resistance • Bronchioles o Each tertiary bronchus branches into multiple bronchioles o Bronchioles branch into terminal bronchioles One tertiary bronchus forms about 6,500 terminal bronchioles o Bronchiole Structure Have NO cartilage Dominated by smooth muscle • Autonomic control regulates smooth muscle o Controls diameter of bronchioles o Controls airflow & resistance in lungs o Bronchodilation: Dilation of bronchial airways Caused by sympathetic ANS activation Reduces resistance o Bronchoconstriction: Constriction of bronchial airways Caused by: • Parasympathetic ANS activationBSC2086 A&P II Exam #4 Study Guide 7 • Histamine – released by mast cells & basophils in anaphylaxis (allergic reactions) • Asthma: Excessive smooth muscle stimulation & bronchoconstriction o Causes bronchiole mucosa to form folds o Stimulation severely
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