Respiratory System

• General functions of the Respiratory System

  1. Air distribution
  2. Gas exchange
  3. Filters, warm, and humidifies air
  4. Regulates pH
• Division of the Respiratory Tract

  • Upper Respiratory Tract

  • Lower Respiratory Tract
• Structures in the upper respiratory tract:

  • Nose
  • Nasal cavity
  • Pharnyx (Naso, Oro, and Laryngo)
  • Larynx
• Structures of the lower respiratory tract:

  • Trachea
  • Bronchi
  • Bronchioles
  • Lungs
  • Alveoli
• Structure of the nose

  External nose/anterior nares -has two nasal bones and cartilage.
• Structure of the nose:

  Internal nose (bones)

  1. Palate (palatine bones, hard & soft palate)
  2. Cribriform plate of the ethmoid bone
  3. Septum (perpendicular plate of the ethmoid bone, the vomer, and cartilage.)
• Nasal cavity

  1. Anterior nares (external opening)
  2. Vestibule (cavity just inside anterior nares)
  3. Meati (below each turbinate bone-superior, middle, and inferior)
  4. Turbinate or conchae (superior, middle, and inferior)
  5. Vibrissae (hairs in the vestibule)
  6. Interior/posterior nares (open into the nasopharynx)
• Nasal mucosa

  1. Respiratory mucosa
  2. Below superior conchae
  3. Many goblet cells and ciliated epithelium
• Olfactory epithelium

  1. Superior conchae and up
  2. Many olfactory nerve cell
• Paranasal sinuses:

  Lined with respiratory mucosa

  Four groups of sinuses

  1. Frontal
  2. Maxillary
  3. Sphenoid
  4. Ethmoid
• Functions of the nose

  1. Passageway for air

  2. Filtering of air

  3. Warming of air

  4. Moistening of air (Lacrimal ducts drain into the inferior nasal meatus)

  5. Chemical examination of air
• The pharynx is divided into three parts: Nasopharynx Oropharynx Laryngopharynx
• Nasopharynx (above the soft palate)

  1. Auditory (eustachian) tubes opening into it
  2. Pharyngeal tonsils (adenoids) on the posterior wall
  3. Posterior nares
• Oropharynx (posterior to fauces)

  1. Fauces (arched opening at the back of the mouth)
  2. Palatine tonsils
  3. Lingual tonsils
• Laryngopharynx:

  Extends from the hyoid bone to the esophagus. It contains:

  1) Opening into larynx

  2) Opening into the esophagus
• Pharyngeal Tonsils

  Three pairs of organs are found in the oropharynx.

  1. Palatine tonsils - behind and below the pillars of the fauces.

  2. Lingual tonsils - at the base of the tongue

  3. Tubal Tonsils - opening of the Eustachian tubes (in the lateral walls of the nasopharynx.)
• Tonsils: Structure and function

  Consists of: ▪ Ring of individual aggregations of lymphoid nodules. Function: ▪ Immune protection of respiratory and digestive mucosa.
• Functions of the pharynx

  1. A common pathway for respiratory and digestive tracts
  2. Phonation (speech production)
• Larynx (voice box)

  Location: Extends from below the tongue to its attachment with the trachea.
• Structure of the Larynx

  a. Cartilage structure

  b. Ciliated mucous membrane lining

  c. Epiglottis (a flap that can close over the glottis)

  d. Vestibular folds (false vocal cords)
• Structure of the Larynx

  e.True vocal folds

  f. Glottis (the true vocal folds and the opening into the larynx)

  g. Vestibule (area above vestibular folds)

  h. Ventricle (area between the vestibular folds and true vocal folds)
• Cartilaginous structure of the Larynx

  Single cartilages

  1. Thyroid cartilage (largest; gives shape)
  2. Epiglottis (flap that can cover glottis)
  3. Cricoid cartilage (below thyroid cartilage)
• Paired laryngeal cartilages

  1. Arytenoid cartilages (move vocal folds)
  2. Corniculate cartilages (on top of arytenoid cartilages)
  3. Cuneiform cartilage (near the base of the epiglottis)
• Muscles of the larynx

  Intrinsic: Control vocal fold length and tension b.

  Extrinsic: Move larynx as a whole
• Functions of the larynx

  1. Air passageway
  2. Filtration, warming, and humidification of air
  3. Prevents the aspiration of solids and liquids
  4. Voice production
• The epiglottis:

  the first piece of cartilage of the larynx is a flexible flap that covers the glottis during swallowing to prevent the entrance of food.
• The thyroid cartilage:

  Protects the front of the larynx. A forward projection of this cartilage appears as the Adam's apple (anatomically known as the laryngeal prominence).
• The Bronchi:

  two tubes that branch from the trachea to the left and right lungs.
• Each primary bronchus divides repeatedly into branches of smaller diameters called bronchioles.
• Alveolar ducts are the final branches of the bronchial tree. Each alveolar duct has enlarged bubblelike swellings along its length. Each swelling is called an alveolus.
• The respiratory membrane consists of the alveolar and capillary walls. Gas exchange occurs across this membrane.
• • Type I cells of the respiratory membrane are thin, squamous epithelial cells that constitute the primary cell type of the alveolar wall. Oxygen diffusion occurs across these cells.
• Type II cells are cuboidal epithelial cells that are interspersed among the type I cells. They secrete pulmonary surfactant.
• Pulmonary surfactant reduces the surface tension of the moisture that covers the alveolar walls. A reduction in surface tension permits oxygen to diffuse more easily into the moisture. A lower surface tension also prevents the moisture on opposite walls of an alveolus or alveolar duct from cohering and causing the minute airway to collapse.
• • A dense network of capillaries surrounds each alveolus. The capillary walls consist of endothelial cells surrounded by a thin basement membrane. The basement membranes of the alveolus and the capillary are often so close that they fuse.
• The function of the respiratory system:

  To deliver air to the lungs. Oxygen in the air diffuses out of the lungs and into the blood, while carbon dioxide diffuses in the opposite direction, out of the blood and into the lungs.
• External respiration is the process of gas exchange between the atmosphere and the body tissues.
• 1. Pulmonary ventilation is the process of breathing—inspiration (inhaling air) and expiration (exhaling air).
• Gas transport, carried out by the cardiovascular system, is the process of distributing oxygen throughout the body and collecting CO 2 and returning it to the lungs.
• Internal respiration is the process of gas exchange between the blood, the interstitial fluids (fluids surrounding the cells), and the cells.