The Respiratory System Structures

Function of the Respiratory System Filters, warms, and humidifies the air we breathe Ensures that oxygen is supplied TO… …and carbon dioxide is removed FROM… the body’s cells Influences speech production Makes olfaction possible

Structures Divided into Upper & Lower Respiratory Tracts Contains Respiratory mucosa: Specialized mucous membrane that lines the respiratory tract Secretes MUCUS air purification mechanism. traps irritants such as dust and pollen Cilia on mucosal cells beat upward, moving mucus to pharynx for removal.

Histology: Pseudostratified Ciliated Columnar Epithelium with Goblet Cells (secrete mucus)

UPPER RESPIRATORY TRACT Nose Nasal cavity Pharynx Naso- Oro- Laryngo- Larynx Mouth Eustachian tubes

Nose Air enters through external nares (nostrils) Nasal septum separates interior of nose into two cavities (composed of ethmoid, quadrangular cartilage, vomer bone) Nose warms and moistens inhaled air, contains organs of smell

Nasal Cavity Lined by bone, mucous membrane Ethmoid Maxilla Nasal bones Warms, moistens, cleans air Cilia trap microorganisms, materials  digestive system Turbinates/conchae direct air to olfactory gland

Sinuses Frontal, maxillary, sphenoidal, ethmoidal sinuses drain into the nose Provide resonance for speech Can become inflamed (sinusitis)

CT Scans Normal vs. Chronic Sinusitis

Pharynx 1. Nasopharynx Mucous-secreting Eustachian tubes Adenoids 2. Oropharynx Digestive component Tonsils 3. Laryngopharynx  larynx Laryngopharynx

Larynx (voice box) Composed mainly of cartilage Bound by ligaments and muscles Contains vocal cords that stretch across from arytenoid to cricoid cartilages Changes in tension changes pitch Superior/anterior to larynx= epiglottis (closes off larynx during swallowing) Anterior larynx=thyroid cartilage (largest, contains Adam’s apple) Inferior larynx=cricoid cartilage Hyoid bone located here

Pathology of the Larynx Vascular polyp w/ varices Laryngocele Leukoplakia & underlying carcinoma

LOWER RESPIRATORY TRACT Located within the thoracic cavity Includes the Trachea Bronchi Lungs Bronchioles Alveolar ducts Alveolar sacs Alveoli

Trachea 4 ½ inches long, from larynx to bronchi Held open by 15-20 C-shaped cartilaginous rings Posterior muscle Obstruction can cause death w/in minutes Ciliated to move mucus out - Smoking affects these   1 - Vocal cords 2 - Thyroid cartilage 3 - Cricoid cartilage 4 - Tracheal cartileges 5 - Balloon cuff

Remainder of Lower Respiratory Tract R & L bronchi  Contain cartilage, smooth muscle R is wider, shorter, more vertical Divide into secondary and tertiary bronchi  Bronchioles (terminal and respiratory)  Lungs (alveolar ducts and sacs)

Bronchi  Bronchioles  Lungs Terminal bronchioles can dilate, constrict Respiratory bronchioles split into 2-11 alveolar ducts each  5-6 alveolar sacs each (look like bunches of grapes)

Alveolar Ducts  Alveolar Sacs  Alveoli Alveolar sacs are microscopic and come in clusters Made up of alveoli: site of gas exchange b/w air and blood Coated with surfactant (reduces surface tension, prevents them from collapsing)

General Structure/Location of the Lungs Lungs: R—3 lobes, L—2 lobes (divide into lobules) Apex: under clavicle Base: above diaphragm Heart in cardiac notch

Lobes and Lobules Functional and structural: Conducting portion Terminal bronchioles Clara cells – remove toxins Type 1 alveolar cells – gas exchange Type II alveolar cells – secrete surfactant Surfactant – reduces surface tension of lungs, allows easier expansion; prevents collapse of alveoli Respiratory portion Gas exchange occurs here

X-Ray: Right apex tumor

More on Lung Structure Pleura: thin, moist, slippery (serous) membrane Visceral pleura: covers the outer surface of the lungs Parietal pleura: lines the inner surface of the rib cage Produces pleural fluid-intrapleural space must remain moist Pathology: Pleurisy (pleuritis) – painful inflammation of the pleura

Collapsed Lung A.k.a. = pneumothorax Caused when atmospheric pressure enters the thoracic cavity Normally a partial vacuum between ribcage and lungs Trauma introduces air, which removes “suction” that keeps lungs inflated Repaired by: chest tube