BSC2086 A P II Exam 4 Study Guide 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 to the lungs o Carried to cells by the cardiovascular system also returns carbon dioxide 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 layer 1 BSC2086 A P II Exam 4 Study Guide Lamina Propria Areolar layer URS trachea bronchi contain mucous glands secrete onto LRS contains smooth muscle cells that encircle lumen of epithelial surface 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 m 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 Cilia sweep debris trapped in mucus toward the pharynx exposed surfaces 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 system 2 BSC2086 A P II Exam 4 Study Guide 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 Thyroid Cartilage Anterior surface called laryngeal prominence connecting the pharynx to larynx o Cartilages of the larynx 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 trachea 3 BSC2086 A P II Exam 4 Study Guide 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 esophagus 4 BSC2086 A P II Exam 4 Study Guide 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 lobes 5 BSC2086 A P II Exam 4 Study Guide o Bronchial Structure bronchi Primary bronchus branches to form secondary bronchi lobar 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 activation 6 BSC2086 A P II Exam 4 Study Guide 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 restricts airflow Bronchitis Inflammation of bronchial walls during infection of bronchi bronchioles o Causes constriction breathing difficulty Each terminal bronchiole branches to form several respiratory bronchioles where gas exchange takes place o Alveolar Ducts Connect respiratory bronchioles to alveoli o Alveolar ducts end at alveolar sacs Common chambers connected to many individual alveoli o Each alveolus has an extensive network of capillaries Surrounded by elastic fibers 7 BSC2086 A P II Exam 4 Study Guide o Alveolar Epithelium Consists of simple squamous epithelium pneumocytes type I Patrolled by alveolar macrophages dust cells Contains pneumocytes type II
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