Respiratory System

• Conducting portion (CP)


  • Respiratory portion (RP)
  • Pumping mechanism (PM)
• Structures of the external nose and nasal cavity

  • External nose and its associated nasal cartilages
  • Muzzle- facial and rostral portions
  • Nasal plane
  • Nostrils/cranial nares
  • Septum
  • Philtrum
  • Alar fold
  • Wing of the nostrils
  • Nasal cartilage

  
• Bony support of the nasal wall

  • Nasal bone
  • Maxillary bone
  • Incisive bone
  • Frontal bone
  • Lacrimal bone
  • Zygomatic bone
  • Palatine bone

  
• Floor of the nasal cavity


  • Parts of the incisive bone
  • Horizontal plate of palatine bone
  • Palatine process of maxillary bone

  
• Nasal cavity


  Opens externally at the nostrils and it communicates posteriorly with the naso-pharynx through the posterior nares, or choanae

  
• Nasal passageways


  • Narrow passageway between the dorsal nasal concha and nasal bone
  • Passageway between the dorsal nasal concha and ventral nasal concha
  • Narrow vertical space between median nasal septum and the conchae
  • Largest, located between the ventral nasal concha and hard palate

  
• Functions of the nasal cavity

  • Olfaction (Macrosmatic, Microsmatic, Anosmatic)
  • Filtration of Inspired Air
  • Warming and Humidifying Inspired Air
  • Frontal Sinus
  • Maxillary Sinus

  
• Functions of the paranasal sinuses

  • Impart resonance to the voice
  • Thermally insulate the nervous centers
  • Lighten the bones of the skull
  • Increase the area of the olfactory meatus
  • Protect the eyes, nasal passages and cranial cavity

  
• Larynx


  • Conducts inspired air from the nasal cavity to the larynx
  • Membranous-cartilaginous valvular apparatus
  • Connects the pharynx and the trachea
  • Caudal to the tongue and soft palate
  • Nine cartilage making up the larynx

  
• Laryngeal cartilages


  • Epiglottis (unpaired)
  • Thyroid (unpaired)
  • Arytenoid (paired)
  • Cricoid (unpaired)

  
• Laryngeal ligaments and membranes

  • Crico-thyroid membrane
  • Thyro-hyoid membrane
  • Hyo-epiglottic ligament
  • Thyro-epiglottic ligament
  • Transverse arytenoid ligament
  • Vocal ligament
  • Ventricular ligament
  • Crico-tracheal membrane
• Laryngeal muscles


  • Extrinsic: Sterno-thyro-hyoid, Thyro-hyoid, Hyo-epiglottic

  Intrinsic: Crico-thyroid, Dorsal crico-arytenoid, Lateral crico-arytenoid, Transverse arytenoid, Ventricular, Vocal

  
• Trachea


  Cartilaginous and membranous tube

  Extends from the larynx to the hilus of the lungs

  Cervical part runs from the larynx to thoracic inlet

  Thoracic part continues at the bifurcation

  Composed of cartilaginous C-shaped tracheal rings

  
• Bronchial tree


  • Right and left primary bronchi

  Secondary bronchi or lobar bronchi

  Tertiary or segmental bronchi

  Bronchioles

  Respiratory bronchioles

  Alveolar duct

  Alveolar sac
• Differences between bronchi and bronchioles

  • Bronchiole is smaller

  Cartilage is absent in bronchioles

  Epithelium in bronchioles is simple not pseudostratified (ciliated pseudostratified in bronchus)
• Lungs


  Paired structures

  Occupies greatly the thoracic cavity

  Organs where the oxygen from the atmosphere and carbon dioxide from the blood are exchanged

  
• Divisions of the lung

  • Apex

  Base

  Costal surface

  Mediastinal surface

  Dorsal border

  Ventral border
• Pleura


  Serous membranes which line the walls of the thorax and are reflected over the surface of the lungs

  Release small amounts of serum-like serous fluid or exudate

  Also known as pleural, pericardial or peritoneal fluid

  Fills the spaces between organs reducing friction between them (e.g. movement of lungs during respiration)
• Parts of the Pleura

  • Costal Pleura

  Diaphragmatic Pleura

  Mediastinal Pleura
• Parietal pleura reflections


  • Vertebral

  Sternal

  Diaphragmatic

  Precardial/ Cranial

  Cardial/ Middle

  Postcardial/ Caudal
• Muscles involved in respiration

  • Scalenus

  Pectoralis

  Latissimus dorsi

  Serratus ventralis

  Intercostal muscles

  Diaphragm

  Transversus thoracis

  Retractor costae

  Serratus dorsalis caudalis

  Abdominal muscles
• Diaphragm


  Forms a partition between the thoracic and abdominal cavities

  Thoracic surface is convex and covered by pleura

  Abdominal surface is concave and is covered by the peritoneum

  Costal part

  Sternal part

  Lumbar part

  Right crus

  Left crus
• A lung is soft and spongy to the touch, it crepitates when pressed, its color is bright pink in life and it floats in the water