Respiratory System Anatomy of the Respiratory System continued 22 1 Upper Respiratory Tract 22 2 Nose Nose extends from nostirls nares to a pair of posterior openings the posterior nasal apertures choanae Functions warms cleanses humidifies inhaled air detects odors resonating chamber that amplifies the voice External Anatomy two upper nasal bones lower half several pieces of hyaline cartilage and dense connective tissue in Nasal septum divides internal chamber or nasal cavity into right and left chambers called nasal fossae Hard palate separates the nasal cavity from the oral cavity and allows one to breathe while you chew food 22 3 Nasal Cavity Just inside nostril find stratified squamous epithelium and vibrissae guard hairs block debris from entering the nose Three folds of tissue or conchae on lateral wall narrow air passage beneath each conchae called meatus narrowness of passages and turbulence ensures air contacts mucous membranes which is then cleansed warmed and humidified Olfactory epithelium lines roof of nasal fossa ciliated pseudostratified columnar epithelium in contact with basement membrane Cilia do not move but catch odor molecules odors are detected by sensory cells in olfactory epithelium 22 4 Nasal Cavity Mucosa Respiratory epithelium mucosa lines rest of nasal cavity with ciliated pseudostratified columnar epithelium traps inhaled particles mucus secreted from goblet cells and mucous glands cilia that propel the debris laden mucus posteriorly to be swallowed and digested has many macrophages lymphocytes and plasma cells and contains large blood vessels to help warm the air 22 5 Regions of Pharynx 22 6 Pharynx muscular funnel with three regions nasopharynx houses the pharyngeal tonsils As air passes through nasopharynx makes 90 degree turn downwards and large articles inhaled cannot make that turn Large particles are stuck in mucosa near tonsils 19 7 Larynx Voice box is a cartilaginous chamber with muscular walls Primary fxn prevent food and fluid from entering the airway but evolved additional role of sound production in many animals Epiglottis flap of tissue that guards glottis superior opening of larynx directs food and drink to esophagus drink out of the airway The folds of the larynx are even more important for keeping food and The inferior vocal cords on both sides of glottis produce sound when air passes between them vibrating them loudness is based on the force of the air passing through the cords Words are formed by the action of the oral cavity tongue and lips acting on the crude sounds of the larynx 22 8 Trachea Rigid tube anterior to esophagus Supported by C shaped hyaline cartilage rings opening in rings faces posteriorly towards esophagus trachealis spans opening in rings adjusts airflow by expanding or contracting The gap in the C covered y the trachealis also allows the esophagus to expand as swallowed food moves down through the esophagus moving along the relaxed trachealis parallel to trachea Trachea and larynx lined with ciliated pseudostratified columnar epithelium The mucus traps inhaled particles and the upward beating of the cilia moves mucus up and out mucociliary escalator 22 9 Lower Respiratory Tract 22 10 Lungs Surface Anatomy Conical with a broad concave base resting on the diaphragm above the clavicle A blunt peak called the apex projecting slightly Much of the space within the rib cage is occupied by the liver spleen and stomach inferior to the lungs and diaphragm The right lung has three lobes while left lung has two lobes 22 11 Pleurae and Pleural Fluid Visceral on outer surface of lungs a serous membrane producing lubricating serous fluid and parietal on inner surface of rib cage pleurae Pleural cavity space between pleurae filled with lubricating pleural fluid The cavity has normally little to no space between the membranes The pleural cavity does not contain a lung rather wraps around each lung Functions reduce friction for fluid acts as a lubricant that eases lung expansion and contraction create pressure gradient lower pressure than atmosphere assists lung inflation compartmentalization by pleurae mediastinum and pericardium prevents spread of infection 22 12 Bronchial Tree Branching system of air tubes within each lung it extends from the main bronchus to 1000s of terminal bronchioles Primary bronchi Secondary lobar bronchi one secondary bronchus for each lobe of lung Tertiary segmental bronchi Like the trachea the main bronchi are supported by C shaped rings of hyaline cartilage All bronchi are lined with pseudostratified columnar epithelium and contain lymphocyte nodules intensely forming clusters nodules Same composition and structure as in trachea and the same mucociliary escalator to remove trapped particles contain elastic connective tissue to provide recoil to expel air smooth muscle which contracts or relaxes to constrict or dilate the airway 22 13 Bronchial Tree Bronchioles no cartilage but layer of smooth muscle in wall less rigid than bronchial No mucus production but have cilia which drive mucus out from above divides into many terminal bronchioles end of air conducting division shift into gas exchange respiratory bronchioles divide into alveolar ducts end in alveolar sacs Alveoli bud from respiratory bronchioles alveolar ducts and alveolar sacs main site for gas exchange 22 14 Path of Air Flow nasal cavity pharynx larynx trachea R L main bronchus lobar bronchus segmental bronchus bronchiole terminal bronchiole respiratory bronchiole alveolar ducts alveolus 22 15 Alveoli In contrast to amphibians and reptiles which have simpler single sac lungs mammals have alveoli which provide er SA for gas exchange er metabolic rate in mammals compared to amphibians and reptiles which requires greater gas exchange in mammals to meet er oxygen demand in tissues An alveolus is a tiny sac 22 16 Alveoli Cells of the alveolus Squamous alveolar cells thin broad cells that allow for rapid gas diffusion between alveolus and bloodstream surrounding alveolus Great alveolar cells cuboidal cells that cover the remaining 5 of alveolar surface repair the alveolar epithelium secrete pulmonary surfactant mixture of phospholipids and proteins prevents the alveoli and smallest bronchioles from collapsing during exhaling supports surface Without surfactant the walls of deflating alveoli would cling together like wet sheets of paper Alveolar macrophages most numerous lung cells wander the lumen and the connective tissue between alveoli Keep