LECTURE EIGHTEEN RESPIRATORY SYSTEM HUMAN ANATOMY LECTURE EIGHTEEN RESPIRATORY SYSTEM

FUNCTIONS Gas exchange - (O2 and CO2) in lungs Regulation of blood pH - alters blood CO2 levels Voice production - movement of air past vocal cords Immunity - protection against microorganisms by preventing entry and removing them from respiratory surfaces Olfactory stimulation – airborne chemicals enter with inhalation

TERMINOLOGY Ventilation - movement of air into and out of lungs External respiration - gas exchange between air in lungs and blood stream Internal respiration - gas exchange between blood and tissues Cellular respiration – production of energy (ATP) in the cell

RESPIRATORY ANATOMY Upper tract Nose, nasal cavity, pharynx, and associated structures Lower tract Larynx, trachea, bronchi, and lungs Respiratory mucosa lines the conducting portion consists of epithelial cells with underlying areolar layer (lamina propria) upper tract layer contains mucosa glands lower tract layer contains bundles of smooth muscle cells Epithelial layer changes: pseudostratified ciliated columnar cells line nasal cavity and pharynx, and portions of lower tract smaller bronchioles become cuboidal with some cilia alveoli contain simple squamous epithelium

NOSE AND NASAL CAVITY External nose composed of cartilage with bone across the bridge Nasal cavity extends from nares through to choane (entrance to pharnyx) - hard palate makes up the floor and separates nasal from oral cavity - nasal septum divides left and right sides - conchae (3) are bony ridges on lateral walls to increase surface area - meatuses are areas between conchae - paranasal sinuses are air filled spaces within bone that open into the nasal cavity and are lined with mucus membrane (reduce weight of skull, produce mucus, influence voice tone)

FUNCTIONS OF NASAL CAVITY - nasolacrimal ducts (carry tears) also enter into cavity - olfactory receptors found in superior area of nasal cavity FUNCTIONS OF NASAL CAVITY passageway for air trap debris from air: - coarse hairs within epithelial lining (stratified squamous epithelium) - pseudostratified columnar epithelium containing cilia and mucus producing goblet cells - mucus traps debris and cilia sweep mucus to pharynx (to be swallowed) air is warmed by nasal capillaries and moistened by mucus smell resonating chambers for speech

PHARYNX Common passageway of respiratory and digestive systems Divided into three regions: Nasopharynx - internal nares to ulva - pseudostratified columnar epithelium with goblet cells - auditory tubes enter - contains pharyngeal tonsils Oropharynx - ulva to epiglottis - stratified squamous epithelium (protects against abrasion from food) - palatine and lingual tonsils Laryngopharynx - from epiglottis to esophagus - lined with stratified squamous and ciliated columnar epithelium

LARYNX

LARYNX Found below hyoid bone in throat Consists of nine cartilages (three are unpaired and six form three pairs) connected by muscles and ligaments epiglottis is attached to thyroid and has flap near base of tongue (elastic rather than hyaline cartilage) largest is the thyroid cartilage (Adam’s apple) most inferior is the cricoid cartilage – forms base of larynx Vocal Cords held together by paired ligaments - superior pair form the vestibular folds (false vocal cords) - inferior pair form the vocal folds (true vocal cords)

FUNCTIONS OF LARYNX Maintain an open passageway for air movement Epiglottis and vestibular folds prevent swallowed material from moving into larynx Vocal folds are primary source of sound production - greater amplitude of vibration, louder the sound - frequency of vibration determines pitch

VOCAL FOLDS

TRACHEA Extends from the cricoid cartilage of the larynx through the mediastium and divides into the right and left bronchi Membranous tube of dense connective tissue and smooth muscle (trachealis) supported by hyaline cartilage 16 to 20 C-shaped tracheal cartilage rings open posteriorly - provide protection and maintain open airway Lined with pseudostratified columnar epithelium with cilia and goblet cells that produce mucus – sweep mucus and debris upward so may be swallowed

BRONCHI Trachea branches in mediastium into right and left primary bronchi C-shaped cartilagenous rings maintain open airway Before branching each primary bronchus travels along the medial groove (hilus) of the lung

BRONCHIAL TREE Primary bronchi divide inside the lungs into smaller passageways - secondary bronchi (two in the left and three in the right lung) Secondary bronchi divide into tertiary bronchi extending to the bronchopulmonary area of the lungs Walls of secondary and tertiary bronchi have progressively less cartilage and more smooth muscle - diameter decreases - pseudostratified columnar epithelium with cilia and mucus producing goblet cells Tertiary bronchi branch into bronchioles and finally terminal bronchioles Terminal bronchioles branch into respiratory bronchioles ending in alveolar ducts - open into alveoli (small sacs) - thin simple squamous epithelium

ALVEOLI Each alveoli is surrounded by an extensive capillary network - capillaries are surrounded by a network of elastic fibers to hold alveoli and bronchioles and push air out Alveolar epithelium is simple squamous epithelium - thin and very delicate for gas exchange Roaming macrophages patrol epithelial surface for foreign particles Septal cells produce superfactant (phospholipids and proteins) - to keep sacs open

RESPIRATORY MEMBRANE Site of gas exchange in alveoli Composed of: (1) squamous cells lining alveoli (2) endothelial cells lining adjacent capillary (3) fused basal laminae between alveoli and endothelial cells Allows for quick exchange of O2 and CO2 across membrane

LUNGS Each is cone-shaped with: - base resting on diaphragm - apex extending beyond clavicle - hilus on medial surface is where bronchi, blood vessels, nerves, and lymphatics enter - form root Divided into lobes (right has three and left has two) separated by deep fissures Each lobe is divided into bronchopumonary segments separated by a connective tissue septa - supplied by tertiary bronchi - divided into lobules - supplied by bronchioles

PLEURA Lungs sit inside thoracic cavity Each lung is surrounded by a separate pleural cavity filled with pleural fluid (lubricant holds membranes close together) Each cavity is lined with a serous membrane called pleura visceral pleura - adheres to lung parietal pleura - adheres to thoracic wall

THORACIC WALL Thoracic vertebrae, ribs, costal cartilages, sternum and associated muscles Thoracic cavity is the space enclosed by the thoracic wall and the diaphragm Diaphragm separates thoracic cavity from abdominal cavity