Respiratory System 2

• Respiration


  Process in which oxygen is used to oxidize organic fuel molecules, providing a source of energy as well as carbon dioxide and water
• Processes included in respiration

  • Ventilation or breathing
  • Exchange of oxygen and carbon dioxide between the air in the lungs and the blood
  • Transport of oxygen and carbon dioxide in the blood
  • Exchange of oxygen and carbon dioxide between the blood and the tissues
• Functions of the respiratory system

  • Regulation of blood pH
  • Olfaction
  • Voice production
  • Innate immunity
• Divisions of the respiratory system

  • Upper Respiratory Tract - External Nose, Nasal Cavity, Pharynx, and associated features
  • Lower Respiratory Tract - Trachea, Bronchi, and Lungs
• Nose


  Consists of external nose and nasal cavity
• External nose


  • Most external nose is composed of hyaline cartilage
  • The bone and cartilage are covered by connective tissue and skin
  • Nares/Nostrils - external openings of the nose
  • Choanae - openings into the pharynx
• Nasal cavity


  • Extends from nares to the choanae
  • Nasal septum - partition dividing the nasal cavity into right and left parts
• Nasal cavity


  • Deviated nasal septum - occurs when the septum bulges on one side
  • Hard palate - forms the floor of nasal cavity
  • Conchae - three prominent bony ridges on the lateral walls
  • Paranasal sinuses - air-filled spaces within bone
  • Sinusitis - inflammation of the mucous membrane of a sinus
• Lining of nasal cavity


  • Stratified squamous epithelium containing coarse hairs
  • Pseudostratified columnar epithelial cells containing cilia and mucus-producing goblet cells
• Nasolacrimal ducts


  Carry tears from the eyes, also open into the nasal cavity
• Sneeze reflex


  Dislodges foreign substances from the nasal cavity
• Pharynx (throat)


  • Common passageway for both respiratory and digestive systems
  • Divided into three regions: Nasopharynx, Oropharynx, and Laryngopharynx
• Nasopharynx


  • Superior part of the pharynx
  • Soft palate - incomplete muscle and connective tissue partition separating nasopharynx from oropharynx, forms the floor of the nasopharynx
  • Uvula - posterior extension of the soft palate
  • Pharyngeal tonsil - posterior part of the nasopharynx that helps defend the body against infection
• Oropharynx


  • Extends from the uvula to the epiglottis, the oral cavity opens into the oropharynx
  • Palatine tonsil - located in the lateral walls near the border of the nasal cavity and oropharynx
  • Lingual tonsil - located on the surface of the posterior part of the tongue
• Laryngopharynx


  Passes posterior to the larynx and extends from the tip of the epiglottis to the esophagus, food and drink pass through it to the esophagus
• Larynx (voice box)


  • Located in the anterior throat and extends from the base of the tongue to the trachea
  • Has three main functions: maintains an open airway, protects the airway during swallowing, and produces voice
  • It is a passageway for air between the pharynx and trachea
• Larynx


  • Consists of nine cartilages connected to one another by muscles and ligaments (3 unpaired, 6 paired)
  • Thyroid cartilage (Adam's Apple) - attached superiorly to the hyoid bone
  • Cricoid cartilage - unpaired and most inferior cartilage of the larynx, forms the base of larynx
  • Epiglottis - third unpaired cartilage that consists of elastic cartilage rather than hyaline cartilage, helps prevent swallowed materials from entering the larynx
  • Cuneiform, corniculate, and arytenoid cartilages - six paired cartilages in the posterior part of the larynx
  • Vestibular folds/False vocal cords (superior) and vocal folds/True vocal cords (inferior) - two pairs of ligaments extending from the posterior surface of the thyroid cartilage to the paired cartilages
• Laryngitis


  Swelling of the vocal folds that inhibits larynx for voice production
• Trachea/windpipe


  • Membranous tube attached to the larynx
  • Consists of connective tissue and smooth muscle reinforced with C-shaped pieces of hyaline cartilage
  • Adult trachea is about 1.4-1.6 cm in diameter and about 10-11 cm long
  • Begins immediately inferior to the cricoid cartilage and divides into right and left primary bronchi at the level of the fifth thoracic vertebra
  • Esophagus lies immediately posterior to the trachea
• Posterior wall of trachea

  Has no cartilage and consists of ligamentous membrane and smooth muscle
• Cough reflex


  Dislodges foreign substances from the trachea
• Bronchi


  • The trachea divides into right and left main/primary bronchi, each connecting to a lung
  • Left main bronchus is more horizontal than the right main bronchus because it is displaced by the heart
  • Foreign objects usually lodge in the right main bronchus
  • Lined with pseudostratified ciliated columnar epithelium and supported by C-shaped cartilages
• Lungs


  • Principal organs of respiration
  • Each lung is cone-shaped, with its base resting on the diaphragm and its apex extending superiorly to 2.5 cm above the clavicle
  • The right lung has three lobes: superior, medial, and inferior
  • The left lung has two lobes: superior and inferior
  • Each lobe is divided into bronchopulmonary segments separated by connective tissue
• Tracheobronchial tree


  The main bronchi branch many times to form this structure
• Bronchial tree


  • Main bronchi divide into lobar bronchi as they enter their respective lungs
  • Lobar bronchi (secondary bronchi) - two in the left lung and three in the right lung, conduct air to each lobe
  • Segmental bronchi (tertiary bronchi) - extend to bronchopulmonary segments of the lung
  • Bronchioles - subdivide into numerous times to give rise to terminal bronchioles
• Terminal bronchioles


  Subdivide into respiratory bronchioles
• Alveolar ducts


  Long, branching hallways with many open doorways (alveoli)
• Alveoli


  Small air sacs where gas exchange between air and blood takes place
• Respiratory membrane


  • Thin layer of fluid lining the alveolus
  • Alveolar epithelium, composed of simple squamous epithelium
  • Basement membrane of the alveolar epithelium
  • Thin interstitial space
  • Basement membrane of the capillary endothelium
  • Capillary endothelium, composed of simple squamous epithelium
• Surfactant


  A chemical secreted by secretory cells within the walls of the alveoli that reduces the tendency of the alveoli to recoil
• Pleural cavities


  • Each lung is surrounded by a separate pleural cavity
  • Pleura - serous membrane lined in the pleural cavity, consists of parietal and visceral part
  • Parietal pleura - lines the wall of the thorax, diaphragm, and mediastinum
  • Visceral pleura - covers the surface of the lung
  • Pleural cavity - filled with a small volume of pleural fluid produced by pleural membranes
• Functions of pleural fluid

  • Acts as a lubricant, allowing the visceral and parietal pleurae to slide past each other as lungs and thorax change shape during respiration
  • Helps hold the membranes together
• Ventilation/breathing


  • The process of moving air into and out of the lungs
  • Two phases: inspiration/inhalation - movement of air into the lungs, and expiration/exhalation - movement of air out of the lungs
  • Regulated by changing the thoracic volume, which produce changes of air pressure within the lungs
• Muscles of inspiration


  • Include the diaphragm and the muscles that elevate the ribs and sternum, such as the external intercostals
• Diaphragm


  Large dome of skeletal muscle that separates the thoracic cavity from the abdominal cavity
• Muscles of expiration


  • Such as the internal intercostals, depress the ribs and sternum
• Changes in volume result in changes in pressure, and air flows from high pressure to low pressure
• Pleural fluid


  It acts as a lubricant, allowing the visceral and parietal pleurae to slide past each other as lungs and thorax change shape during respiration
• Pleural fluid


  It helps hold membranes together
• Ventilation/Breathing


  The process of moving air into and out of the lungs