gas exchange

• parts of human gas exchange system?

  alveoli , bronchioles , bronchi , trachea ,lungs
• what happens during inspiration?


  external intercostal muscles contract , internal relax , diaphragm contracts , air pressure drops, volume increases ,air moves in
• what happens during expiration?


  external intercostal muscles relax, internal contract , diaphragm relaxes , pressure higher than atm , volume decreases , air moves out
• adaptations for gas exchange in aveoli?


  large surface area to volume ratio

  one cell thick - small diffusion distance

  network of capillaries
• how do insects limit water loss?


  small surface area to volume

  waterproof exoskeleton

  spiracles which open and close
• how do insects gas exchange?

  through their trachea system
• how to insects move gas?


  1)diffusion between tracheoles and atmosphere

  2)contracting abdominal muscles

  3)respire anaerobically producing lactate
• adaptations of an insect for gas exchange?

  large surface area to volume

  short diffusion pathway

  steep gradients
• parts of the fish gas exchange system?

  gill arch , operculum , filaments , lamellae
• why is there a short diffusion distance?

  flattened cells in gill plates epithelium
• why is there a steep conc gradient?

  highly capillarised
• large surface are due to in fish ?

  gill filaments and lamellae
• what is countercurrent?


  water and blood flow in opposite directions , blood always flows next to water that has higher oxygen concentration so that diffusion goes across full length of lamellae
• Why can't fish simply diffuse oxygen across their surface?

  They have a small surface area to volume ratio
• What is the gas exchange surface in fish?

  The gills
• How much less oxygen does water contain compared to air?

  30 times less oxygen
• What are the three key features of every gas exchange surface?

  Large surface area, short diffusion distance, concentration gradient
• What adaptations do fish gills have for gas exchange?

  • Large surface area due to many gill filaments
  • Short diffusion distance from thin gill lamellae
  • Counter current flow to maintain concentration gradient
• How many layers of gills do fish have on each side of their head?

  Four layers
• What are the gill filaments in fish?

  Long parts sticking out from the gills
• How do gill lamellae contribute to gas exchange?

  They provide a large surface area for diffusion
• What is the orientation of gill lamellae in relation to gill filaments?

  They are positioned at right angles
• What happens to water as it flows over the gills?

  It rushes out through a gap in the head
• What provides a short diffusion distance in gill lamellae?

  The thin structure of the lamellae
• How is the concentration gradient maintained in fish gills?

  Through counter current flow of water and blood
• What is the difference between counter current flow and concurrent flow?

  Counter current flow prevents equilibrium
• What is the effect of concurrent flow on oxygen diffusion?

  It leads to equilibrium and reduced diffusion
• What is the saturation level of water entering the gills?

  100% saturation with oxygen
• Why is counter current flow advantageous for fish?

  It maintains a diffusion gradient across the lamellae
• What is the key reason for maintaining a diffusion gradient in fish gills?

  To ensure oxygen diffusion occurs continuously
• What are the three features of gas exchange surfaces in fish?

  • Large surface area to volume ratio
  • Short diffusion distance
  • Mechanism to maintain concentration gradients
• What is the primary function of gills in fish?

  To facilitate gas exchange
• What happens to the concentration of oxygen in water as it flows over the gills?

  It decreases from 100% to near 0%
• How does the structure of gills enhance gas exchange efficiency?

  By maximizing surface area and minimizing diffusion distance
• What is the purpose of the exoskeleton in terrestrial insects?

  To protect and prevent water loss
• What is the significance of the term "entire length" in gas exchange?

  It indicates diffusion occurs along the full length of lamellae
• What material is the exoskeleton of terrestrial insects made of?

  Chitin
• What is the role of capillary networks in gill lamellae?

  They provide a short diffusion distance for gases
• How does the counter current exchange principle benefit fish?

  It prevents equilibrium and maintains oxygen diffusion
• Why don't terrestrial insects have lungs?

  They have a tracheal system for gas exchange