Respiratory

• Ventilation


  Movement of air into and out of lungs - expiration and inspiration - controlled by diaphragm and ribcage
• Gas exchange


  Diffusion of oxygen and carbon dioxide between blood and respiring tissues - interface of alveoli
• Cell respiration


  Production of ATP in mitochondria - releases carbon dioxide, requires oxygen
• Breathing


  Movement of air into/out of lungs
• External respiration


  Exchange of oxygen and carbon dioxide between air and blood
• Internal respiration


  Exchange of oxygen and carbon dioxide between blood and tissue fluid
• Arrhythmia/dysrhythmia


  Irregular heart rate
• Dyspnoea


  Irregular breathing
• Apnoea


  Absent breathing
• Tidal volume

  Volume of air moving in and out of lungs - autonomic
• Inspiratory reserve volume


  Volume of air taken in during forced inhalation
• Expiratory reserve volume


  Volume of air forced out during expiration
• Residual volume


  Volume that can't be forced out
• Total lung capacity


  All volumes except residual
• Inspiratory capacity


  Tidal volume and inspiratory reserve volume
• Functional residual capacity


  All air left in lungs after expiration of tidal volume
• Vital capacity


  Inspiratory reserve + tidal + expiratory reserve
• Anatomic dead space


  Air which doesn't make it to alveoli - sits in conducting airway
• Alveolar dead space


  Air gets to alveoli - no gas exchange
• Total dead space


  Total air not involved in gas exchange
• Atmospheric pressure


  Pressure of gases in atmosphere
• Interalveolar pressure


  Pressure in alveoli
• Intrapleural pressure


  Negative pressure between pleura - more negative than alveolar
• Transpulmonary pressure


  Difference between intrapleural and interalveolar pressure
• Upper respiratory tract (conducting zone)


  • Nares, nasal passages, pharynx, larynx
• Upper respiratory tract


  • Immune defence
  • Humidify air
  • Thermoregulation
  • Phonation
• Nose


  • External nose, nares, paired nasal cavities and paranasal sinuses
• Nasal planum/nosepad/rhinarium


  Divided by philtrium, surrounded by hairless skin, secretions from lateral nasal glands within nasal mucosa (opens rostrally at nasolactrimal duct), serous gland (watery secretion), part of thermoregulation and moistened by tear drainage. Alar fold formed by ventrolateral nasal cartilage to flare nostrils. All made of cartilage
• Nasal cavities


  Moistens, warms, filters air, olfaction. Bored by facial bones (dorsolateral), oral cavity and hard palate (ventral), nares (rostrally) and pharynx/ethmoid bone separating nasal cavity and brain (caudal)
• Ethmoid bones


  Filter and moistens air
• Turbinate bones


  Restrict airflow - small channels (meatus)
• Paranasal sinuses


  Diverticular of nasal cavity - excavate skull - small openings into nasal cavity - limits airflow. Protects skull, thermoregulation, right shape for muscle attachment
• Cribriform plate of ethmoid bone

  Further divided into nasal meatuses by nasal conchae (turbinate) - lined with mucosa, increases nasal surface area, vascular, nerve extensions from olfactory bulb. Dorsal (olfactory), middle (sinus system), ventral (route to pharynx) meatuses branch
• Dogs - paired frontal sinus and maxillary recess
• Turbinate bones


  • Block large particles
• Goblet cells and ciliated epithelium

  • Produce mucous and move into pharynx to be swallowed
• Pharynx


  Large air filled cavity. Oropharynx and nasopharynx are divided by soft palate - join to form laryngopharynx. Nasopharynx begins at back of nasal cavity and more dorsal, oropharynx begins at back of oral cavity. Laryngopharynx - in front of larynx. Stratified squamous epithelium - resistant to abrasion.
• Prevent inhalation of food

  Epiglottis - covers entrance to larynx when swallowing - soft palate moves up. Hooks onto back of soft palate when breathing
• Trachea is ventral to oesophagus
• Larynx


  Voicebox. Stratified squamous epithelium - resistant to abrasion. Connects pharynx to trachea. Protects lower respiratory tract from food/water. Held in place by muscles. Air passes - vocal cords vibrate.