Respiratory System

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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

• Cutaneous respiration
• Amphibians

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Pharynx

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

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Internal Gills

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

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Pharyngeal gills
Mouth
Pharynx
Gill filaments
Cartilaginous support
Gill arch
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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

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Gill surface
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Gill structure

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

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Gill Structure

• Gill rakers
• Inner surface of gills
• Keeps food out of gills

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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

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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

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Counter current exchange
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NOT Countercurrentexchange

• Fluids flow in the same direction
• equilibrium between the two fluids occurs

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• Fluid flow
• in opposite direction
• Equilibrium never
• occurs

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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?

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Misc. Gill functions

• Sodium absorption excretion
• Nitrogen waste excretion

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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

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Lampreys
Gill slits
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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

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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

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Opercular gills
Gill arch
Gill filaments
Mouth
Operculum
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Opercular gill
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Opercular gill
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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

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Swim Bladder

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

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Swim bladder

• Physostomous
• Bladder open open pneumatic duct
• Physoclistous
• Bladder closed closed pneumatic duct

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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

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Key Points

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

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Swim Bladder

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

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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

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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?

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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

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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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Anuran Respiration

• Trachea and bronchi
• Supported by cartilaginous rings
• Lungs are the location of gas exchange
• Ventilation involves gulping (pulse pump) and
  internal nares are functional for first time in
  evolutionary history

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Respiration gas exchange
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Amphibian Respiration

• Urodeles
• Lungs often of minor importance
• Respiration often through external gills and skin

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Reptile Respiration

• Similar to amphibians in anatomy
• Ventilation is by suction
• Inspiration involves creating negative pressure
  inside chest cavity via intercostal and abdominal
  muscles
• Expiration is passive

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Mammal Respiration

• Larynx
• Vocal cords
• Arytenoid cartilage supports vocal cords
• Cricoid cartilage
• New Thyroid cartilage
• New epiglottis

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Mammal Respiration

• Trachea
• Incomplete cartilaginous rings
• Cilia

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Mammal Respiration

• Bronchi
• Primary, secondary, tertiary
• Bronchioles tiniest of airways, lacking
  cartilage in walls

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Mammal respiration

• Lungs
• Alveoli
• Millions of tiny air sacs where gas exchange
  occurs

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Mammal Respiration

• Ventilation
• Diaphragm creates sucking or negative pressure
  for inspiration
• Expiration is passive

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Avian Respiration

• Very unique respiratory system
• Trachea delivers air to Bronchi
• The primary bronchi divided into
• Several Ventrobronchi
• Several Dorsobronchi
• Thousands of Parabronchi between

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Avian Respiration

• Air capillaries
• Open ended in the walls of parabronchi
• Form a honeycomb appearance
• Highly vascularized

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Avian Respiration

• Extremely efficient ventilation
• One way air flow
• Air sacs act as bellows to allow continuous
  ventilation
• Efficient diffusion between air capillaries and
  blood capillaries

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Avian Respiration

• Air sacs
• Abdominal 2
• Posterior thoracic 2
• Anterior thoracic 2
• Cervical 2
• Interclavicular - 1

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Air sacs
Trachea
Anterior air sac
Lungs
Posterior air sac
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Avian Respiration

• Air Sac Functions
• Penetrate some bones making them lighter (hollow)
• Ventilation continuous, but no exchange of
  gases
• Thermoregulatory
• Buoyancy in water fowl

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Key points

• Why do you suppose avian respiration is so
  efficient more so than in mammals?

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Avian respiration

• Unique syrinx
• In interclavicular air sac region
• Vocal apparatus

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Key Points

• Name two respiratory structures unique to birds.
• Name two respiratory structures unique to mammals.