The Respiratory System Fall 2017 Anatomy and Physiology lab II Dr. Santos

Upper respiratory tract- consists of the passages superior to the thoracic cavity Lower respiratory tract- within the thoracic cavity Conducting zone- passages that carry air to the lower respiratory passages where gas exchange takes place. Respiratory zone- passages in which gas exchange occurs.

General structure of the respiratory system Respiratory tract- Series of highly branching passages that conducts air to the structures of gas exchange. Parietal pleura- Outer layer of the pleural membrane that lines the interior of the thoracic cavity and the superior surface of the diaphragm. Visceral pleura- Inner layer of the pleural membrane that adheres tightly to the lung. Pleural cavity- Very thin potential space between the parietal and visceral pleura that contains a thin layer of serous fluid. Lungs and lobes- Lungs are organs composed of elastic connective tissue and tiny air sacs called alveoli. Each lung is divided into sections (three in the right lung and two in the left lung) called lobes.

Right lobes- (upper, middle and lower) Left lobes- (upper and lower) Fissures-deep indentations that separate the lobes. Horizontal fissure-separates right upper lobe and right middle lobe Right oblique fissure-separates the right middle and right lower lobe Left oblique fissure- separates the left upper lobe and left lower lobe

Structures of the Respiratory Tract Nasal cavity- Area within the skull framed by cartilage and bone that extends from the anterior nares to the posterior nares; filters, warms, and moistens inhaled air. Pharynx- The area located posterior to the nasal cavity (the nasopharynx), the oral cavity (the oropharynx), and the larynx (the laryngopharynx) Larynx Cartilage-framed region of the respiratory tract within the neck that houses the vocal cords Trachea -Portion of the respiratory tract in the inferior neck and superior mediastinum that connects the larynx with the bronchial tree Primary bronchi- The initial branches off the trachea that each serve one lung Secondary bronchi- Branches off the primary bronchi that each serve one lobe of the lung Terminal bronchioles Passageways smaller than 0.5 mm in diameter that control airflow to the structures for gas exchange

Respiratory bronchioles- Small branches off the terminal bronchioles that have alveoli in their walls Alveolar ducts- Portion of the respiratory bronchiole made up exclusively of alveoli Alveoli- Terminal structures of the respiratory tract; consist primarily of thin simple squamous epithelium through which gases are exchanged with the blood

Larynx

Air passes from the pharynx to the larynx, a short passage framed by 9 cartilages. The lid- is a piece of elastic cartilage known as the epiglottis The thyroid cartilage- a large cartilage that forms the anterior and lateral walls of the larynx Cricoid cartilage- inferior to the thyroid cartilage Cricothyroid ligament- a soft ligament between the thyroid and cricoid cartilage Laryngeal prominence- “Adam's apple”

“Voice box” Common name for larynx Vocal folds/cords- 2 sets of elastic ligaments Superior set (false vocal cords)- play no role in sound production but serve sphincter function) Inferior set- they vibrate as air passes over it to produce sound.

Passage of air Start: nasal cavity ➜ nasopharynx ➜ oropharynx ➜ laryngopharynx ➜ larynx ➜ trachea ➜ primary bronchus ➜ secondary bronchus ➜ tertiary bronchus ➜ multiple smaller bronchi ➜ bronchiole ➜ terminal bronchiole ➜ respiratory bronchiole ➜ alveolar duct ➜ alveolus End

21.3 Lung inflation Cricrothyroidotomy- procedure used to unblock the air passageway 1- Place an incision in the cricothyroid ligament (soft spot) 2- insert a tube into the opening 3- ventilate patient artificially THIS RESTORES THE PATIENT’S AIRWAY BY BYPASSING THE UPPER RESPIRATORY SYSTEM.