Respiratory

• Respiratory system ensure adequate supply of oxygen and eliminate carbon dioxide.
• External respiration: Oxygen and carbon dioxide exhanged between the external environment and the body cells.

  
  

  Internal respiration: Cells use oyxgen for ATP production (and produce carbon dioxide in the process)
• Adaptations for external respiration

  Primary organs in adult vertebrates are external and internal gills, swim bladders or lungs, skin, and buccopharyngeal mucosa.
• Less common respiratory devices are filamentous outgrowths of the posterior trunk and thigh (African hairy frog), lining of the cloaca, and lining of the esophagus.
• Ventilatory mechanism

  Cilia: tiny, hair-like structures found in the respiratory tract lining that helps to remove debris, dust, and mucus from the airways.

  In smaller animals with modest metabolic demands, such as some small mammals or reptiles, their respiratory systems are adapted to meet their specific needs.

  Surfactant: reduces surface tension at the water-air interface
• Inspiration: term for inhalation

  Expiration: term for exhalation
• Ventilation mechanism in fishes and amphibians depends on muscle action.
• Air exchanged via negative pressure ventilation, with pressures changing due to contraction & relaxation of diaphragm & intercostal muscles.
• Mammalian lungs

  • Aspiration pump ventilates the lungs
  • Air flow is bidirectional and involves the rib cage and diaphragm.
• Air sacs (diverticula of lungs) are extensively distributed in avian lungs.
• Two lungs are ventilated by aspiration pump in avian lungs
• Reptilian Lungs

  Snakes and lizards: single air chamber

  Lizards, crocodilians, and turtles: single chamber with numerous internal chambers

  Filling is based on aspiration pump mechanism
• Skin


  What is the major respiratory organ of Amphibians?
• Amphibian lungs

  • Two simple sacs
  • Internal lining may be smooth or have pockets
  • Air exchanged via positive pressure ventilation
• Trachea

  • Usually about as long as a vertebrates neck (except for a few birds such as cranes)
  • Reinforced by cartilaginous rings (or c-rings)
• Trachea splits into 2 primary bronchi & in birds only, forms the syrinx.
• Larynx

  • Tetrapods besides mammals: arytenoid and cricoid
  • Mammals: paired arytenoids, cricoid, thyroid, and epiglottis
  • Have vocal cords (amphibians, some lizards, and most mammals)
• T or F. Swim bladders may be paired or unpaired.

  T
• During development, swim bladders are usually connected to the esophagus:

  1. Physostomatous: the duct remains open in bowfins and lungfish
  2. Physoclistous: the duct closes off in most teleosts
• Swim bladders serve primarily as a hydrostatic organ (regulating a fish's specific gravity).
• Some freshwater teleosts 'hear' by the way of pressure waves transmitted via the swim bladder and small bones called Weberian ossicles.
• Aside from serving primarily as a hydrostatic organ, swim bladders may also play important roles in hearing, sound production, and respiration.
• Vertebrates without swim bladders or lungs include cyclostomes, cartilaginous fish, and few teleost (flounders and other bottom dwellers).
• Most vertebrates develop an outpocketing of pharynx or esophagus that becomes one or a pair of sacs (swim bladders or lungs).
• Larval gills

  External gills: outgrowths from the external surface of 1 or more gill archers

  Filamentous extensions of internal gills: project through gill slits
• Larval gills

  External gills: found in lungfish and amphibians

  Filamentous extensions of internal gills: occur in early stages of development of elasmobranchs
• Gas Bladders

  • sac filled with gases via pneumatic duct
  • connected to digestive tract
  • buoyancy and respiration
  • Actinopterygians (type of Osteichthyes)
• Cutaneous respiration


  Respiration through the skin can take place in air, water, or both
• Gills

  Cartilaginous fishes

  • 5 'naked' gill slits
  • Gill rakers: protrude from gill cartilage and 'guard' entrance into the gill chamber

  Bony fishes (Teleosts)

  • Usually have 5 gill slits
  • Operculum projects backward over gill chambers
  • Interbrachial septa are very short or absent.
• Dual pump

  • water ventilation that is common in water-breathing (gnathostome)
  • Two pumps: buccal and opercula
• Pump for air ventilation

  Air-breathing fishes: Buccal

  Reptiles: Aspiration

  Lungfishes: Buccal

  Birds: Aspiration

  Amphibians: Buccal

  Mammals: Aspiration
• Airflow is bidirectional? Yes or No.

  Buccal: Yes

  Aspiration: Yes
• Types of Air Ventilation

  Buccal pump: gulps atmospheric air

  Aspiration pump: air is sucked in by low pressure created around the lungs