Paramedicine: Upper Respiratory System (HYBRID 1)

• PAR3615 stands for Paramedicine – Medical Physiology II W2025
• Lecture 6 is about Respiratory I – Hybrid I

Upper Respiratory System

• The nose is the only external portion of the respiratory system.
• The nose and paranasal sinuses provide an airway for respiration.
• They also moisten and warm the entering air.
• They filter and clean inspired air.
• The nose and paranasal sinuses serve as a resonating chamber for speech.
• They house olfactory receptors.
• The nose is divided into two regions: the external nose and the nasal cavity.

The Nose - External

• The external nose consist of:
  • Root (area between eyebrows)
  • Bridge
  • Dorsum nasi (anterior margin)
  • Apex (tip of nose)
• Nostrils (nares) are bounded laterally by alae.
• The external nose is formed by:
  • Nasal and frontal bones superiorly, forming the bridge and root.
  • Maxillary bones laterally
  • Plates of hyaline cartilage inferiorly.

The Nose and Paranasal Sinuses (cont.)

• The nasal cavity is found within and posterior to the external nose and is divided by a midline nasal septum.
• The nasal septum is formed anteriorly by septal cartilage.
• Posteriorly, the septum is formed by the vomer bone and the perpendicular plate of the ethmoid bone.
• The posterior nasal apertures (choanae) are the openings where the nasal cavity turns into the nasopharynx.
• The roof of the nasal cavity is formed by the ethmoid and sphenoid bones.
• The floor of the nasal cavity is formed by the hard palate (bone) and the soft palate (muscle).

Nasal Conchae

• Nasal conchae (kon'ke) are scroll-like, mucosa-covered projections that protrude medially from each lateral wall of the nasal cavity.
• There are three sections of nasal conchae: superior, middle, and inferior.
• Nasal meatus is the groove inferior to each concha.
• The shape of the conchae:
  • Increases mucosal area.
  • Enhances air turbulence.
• The nasal conchae functions include:
  • During inhalation, conchae and nasal mucosa filter, heat, and moisten air.
  • During exhalation they reclaim heat and moisture.

The Pharynx

• The pharynx is a funnel-shaped muscular tube that runs from the base of the skull to vertebra C6.
• It connects the nasal cavity and mouth to the larynx and esophagus.
• The pharynx is composed of skeletal muscle.
• There are three regions of the pharynx:
  • Nasopharynx
  • Oropharynx
  • Laryngopharynx

Lower Respiratory System

• The lower respiratory system consists of the:
  • Larynx
  • Trachea
  • Bronchi
  • Microscopic structures
  • Lungs
• The lower respiratory system is divided into two zones:
  • Conducting zone which transports gas to and from gas exchange sites, and also cleanses, warms, and humidifies air.
  • Respiratory zone which is the site of gas exchange.
  • Consists of all other respiratory structures such as respiratory bronchioles, alveolar ducts, and alveoli.

Lower Respiratory - Larynx

• The larynx (voice box) extends from the 3rd to 6th cervical vertebra and attaches to the hyoid bone.
• It opens into the laryngopharynx and is continuous with the trachea.
• Three functions of larynx:
  • Provides a patient airway
  • Routes air and food into proper channels
  • Voice production
• The larynx houses vocal folds.

Larynx - Structure

• Larynx framework consists of nine hyaline cartilages, excluding the epiglottis.
  • The thyroid cartilage which contains a laryngeal prominence is large and shield-shaped.
  • The cricoid cartilage is ring-shaped.
  • The paired arytenoid cartilages.
  • The paired cuneiform cartilages.
  • The paired corniculate cartilages.
  • Epiglottis
• These are all connected by membranes and ligaments.