RESPIRATORY TRACT OF MAMMALS AND AVIANS

• Primary function is to deliver oxygen to the cells of the body’s tissues and remove carbon dioxide
• Main structure: nasal cavity, trachea , lungs
• Defense mechanisms

  > the respiratory tract is coated

  with mucus that is high in water

  › cilia propel a liquid layer of

  mucus that covers t h e airways

  > air picks up water and the

  mucus layer traps pathogens

  and other particles

  • particulates in the air are

  removed in the nasal passages.
• Trachea

  • Funnel the inhaled air to the lungs and the exhaled air out of the body
  • made of incomplete hyaline cartilage and smooth muscles
  • pharynx > larynx > trachea
• Nasal cavity t h e respiratory tract is coated

  with mucus that is high in water

  • cilia propel a liquid layer o f

  mucus t h a t covers t h e airways

  • air picks up water and t h e

  mucus layer traps pathogens

  and other particles

  • particulates in t h e air are

  removed in t h e nasal passages.
• Lungs

  • Lungs > two primary bronchi > secondary bronchi > tertiary bronchioles > alveoli
  • End of the trachea bifurcates to the right and left lungs
  • In the lungs there is bronchi , made up of cartilage and smooth muscles.
  • And then bronchioles, made up of elastic fibers, leads to small sacs called alveoli
• Bronchi are innervated by nerves of both parasympathetic and sympathetic nervous systems that control muscle contractions, relaxation, etc
• Bronchioles with a diameter than 0.5 mm are the respiratory bronchioles

  rely on inhaled air to support their shapes
• Alveolar ducts are attach to the end of each bronchioles; each ducts ends in approximately 100 alveolar sacs.
• • each alveolar sac contains 20 to 30 alveoli that are 200-300 microns in diameter.
  • alveoli are made of thin-walled parenchymal cells that are in direct contact with capillaries of the circulatory system.
  • oxygen will diffuse from alveoli into the blood and carbon dioxide will diffuse from blood to alveoli.
• mamalian respiratory cycle

  inhaled air > nasal cavity > pharyx > larynx > trachea > lungs > two primary bronchi > secondary bronchi > tertiary bronchioles > alveolar ducts > alveolar sacs > alveoli > oxygen from alveoli diffuse to blood and from blood carbondioxide diffuse into the alveoli and then the air goes up to exhale and repeat the process each breath
• Avian respiratory

  Birds have small lungs and nine air sacs

  have evolve into directional respiratory system that allows them to get oxygen at high altitudes
• (Avian)

  Defense mechanism

  • cillia - in trachea
  • mucus
  • Scavenging cells - ingest and eliminate bacteria stopping it from spreading
• avians

  their small lungs cannot inflate because they lack a diaphragm and pleural cavity
• avians

  Parabronchi - continous tube passage allows air to pass through the lungs in one direction. Laced with blood capillaries where gas exchange occurs.
• • Air sacs - balloon-like structures at the extremities of the bird’s airway
  • nine air sacs - an unpaired one in the cervical area, two interclavicular air sacs, two abdominal air sacs, two anterior thoracic air sacs and two posterior thoracic air sacs.
  • air flows - in one direction from the posterior air sacs to the lungs and out of the anterior air sacs. The flow of air is in the opposite direction from blood flow.
• Other organs of avians

  • trachea - made of cartiliginous rings that prevent its collapse from the negative pressure caused by inspiration of air when the bird breaths air.
  • glottis - closes when feed is passing down the throat so it does not enter the lungs
  • syrinx - voice box of avians
  • larynx - respiratory valve protects the airway
• avian respi cycle

  • 1st inhale - air > lungs > posterior air sac
  • 1st exhale - moves to lungs tissue
  • 2nd inhale - waste air moves to anterior air sacs
  • 2nd exhale - anterior air sacs > trachea > out of the body, repeat the process each breath
• related terms to respiratory system

  • Eupnea - normal, good unlabored breathing, quiet breathing.
  • Dyspnea - feeling of difficult, shortness of breathing
  • Hyperpnea - increase volume of air taken during breathing
  • Polypnea - excessively high rate of breathing
  • Tachypnea - abnormal rapid breathing