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Respiratory System

Respiratory System. External respiration- gas exchange between environment & body by diffusion Internal respiration – gas exchange between blood & cells & usage of gas by cells Ventilation – bringing gas in contact with respiratory exchange surface Water through gills Air in & out of lungs.

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Respiratory System

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  1. Respiratory System • External respiration- gas exchange between environment & body by diffusion • Internal respiration – gas exchange between blood & cells & usage of gas by cells • Ventilation – bringing gas in contact with respiratory exchange surface • Water through gills • Air in & out of lungs

  2. Respiratory system • Cutaneous respiration • Amphibians

  3. Pharynx • External gills • Some urodeles, dipnoans • Form from skin ectoderm • Beginning function early in life

  4. Internal Gills • Within the contours of the body • Development • Internal pharyngeal pouches • External visceral grooves • Visceral arches for support • Aortic arches • Gill opening

  5. Pharyngeal gills Mouth Pharynx Gill filaments Cartilaginous support Gill arch

  6. Gill Bar • All gill structures between the openings, including visceral arches • Visceral Skeleton • Blood vessels (from aortic arch) and nerves • Branchial muscles • Respiratory epithelium – gill filaments with lamellae to increase surface area

  7. Gill surface

  8. Gill structure • Gill septae or interbranchial septum is between gills and the gill bar extends to body surface for more support

  9. Gill Structure • Gill rakers • Inner surface of gills • Keeps food out of gills

  10. Gill structure according to filaments • Holobranch – gill filaments on both sides of gill • Hemibranch – gill filaments on one side of gill • Pseudobranch – false gill, faces into spiracle and monitors oxygen requirements to eye

  11. Blood flow through gills • Afferent branchial artery • Capillary beds for diffusion • Efferent branchial artery • Countercurrent flow • Water flows inside to outside • Blood flows outside to inside

  12. Counter current exchange

  13. Blood Water 20% 100% 30% 35% 40% 45% 50% 55% 60% 90% 85% 80% 75% 70% 75% 60% NOT Countercurrentexchange • Fluids flow in the same direction • equilibrium between the two fluids occurs

  14. Blood Water 20% 20% 30% 40% 50% 60% 70% 80% 30% 40% 50% 60% 70% 80% 90% 100% Fluid flow in opposite direction Equilibrium never occurs

  15. Key Points • What does the term “countercurrent” actually mean. How does this relate to the water and blood flow? • What is the advantage of countercurrent flow?

  16. Misc. Gill functions • Sodium absorption & excretion • Nitrogen waste excretion

  17. Gill Classification • Pouched gills • 5-15 • Agnathans • External & internal branchial pores • Pulsations of branchial muscles move water in and out of same openings, as mouth is attached to prey

  18. Lampreys Gill slits

  19. Gill Classification • Septal gills • Septae support gills and look like a set of stacked plates = Elasmobranchs • Spiracle is modified first gill pouch for water intake • Ventilation of gills

  20. Gill Classification • Opercular gills • Little or no septum because • Operculum covers and protects gills • Most do not have spiracle, some do • Ventilation is similar to shark

  21. Opercular gills Gill arch Gill filaments Mouth Operculum

  22. Opercular gill

  23. Opercular gill

  24. Swim Bladder • Homology to lungs • Develops from endoderm • Swim bladder dorsal, lungs ventral • About ½ bony fish have swim bladders • 20 fish genera are air breathers • Seen in Devonian period 350-400 mya

  25. Swim Bladder • Pneumatic duct • Present during development • Connects pharynx and swim bladder • May stay open, may close

  26. Swim bladder • Physostomous • Bladder open – open pneumatic duct • Physoclistous • Bladder closed – closed pneumatic duct

  27. Swim bladder • Physoclistous swim bladder is hydrostatic • Gas gland – anterior area of bladder where gas is secreted from blood to bladder • Rete mirabile – marvelous network, red due to blood vessels • Countercurrent blood flow

  28. Key Points • What is the function of a hydrostatic swim bladder? • Why must the pneumatic duct be closed for a hydrostatic bladder?

  29. Swim Bladder • Physostomous Swim Bladder • Ventilation from mouth to pneumatic duct to swim bladder

  30. Misc. Swim Bladder functions • Resonance chamber for sound production • Sound & pressure reception • Weberian ossicles in some catfish, minnows, carp that transmit sound waves to inner ear ears

  31. Key Points • Weberian Ossicles are associated with swim bladders in some fish. However, they function like our middle ear ossicles. Name our middle ear ossicles. What is the term for describing nonrelated structures that function similarly?

  32. Tetrapod Respiratory Tree • Paired lungs (left & right) • More surface area than fish and more compartmentalization (e.g. lobes) • Trachea connects throat with bronchial tree • Blood flow is tremendous for gas exchange

  33. Amphibian Respiration • Air is moved by pulse pump or forcing it through gulping • Anurans • Larynx – cartilaginous entry into trachea • Glottis is opening in larynx • Arytenoid cartilages flank the glottis and support vocal cords; Cricoid is last part of larynx

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