Gas Exchange

• Name 3 organisms with a specialised system for gas exchange.

  Fish, insects, plants
• What are the components of an insects gas exchange system?

  Tracheae, spiracles, and tracheoles.
• How are insects adapted for gas exchange?

  Thin walls - decrease length of diffusion path - increased rate of diffusion

  Tracheoles branching - increases surface area + decreases diffusion path - increasing rate of diffusion

  Fluid is contained within the tracheoles - maintaining concentration gradient - increasing rate of diffusion
• How do insects reduce water loss?

  The spiracles can open and close

  Contain a waxy cuticle
• What are the components of a fish's gas exchange system?

  Gill fillaments

  Lamella

  Counter-current system
• What is the counter-current system in fish?

  When the water above flows in the opposite way to the bloodstream.
• How are fish adapted for gas exchange?

  Both the gills and lamellea are thin - decreasing length of diffusion path - increasing rate of diffusion

  Lamellea - increase surface area - increasing rate of diffusion

  Counter-current system - not limiting diffusion to 50% - increasing rate of diffusion
• What are the key parts of a plant's gas exchange system?

  Stroma

  Guard cells

  Mesophyll layer
• How are plants adapted for gas exchange?

  Stroma have the ability to open and close - helping counteract gas exchange

  Mesophyll layer - large surface area - increase rate of diffusion

  Waxy cuticle - keeps water in - reducing water loss

  Cacti have needles rather than leaves - reducing water loss
• How do stroma open

  When guard cells become turgid they open, when flusid they close.
• What is the site of photosynthesis for a leaf?

  Mesophyll layer
• Particulate matter is solid particles and liquid particles suspended in air.

  Polluted air contains more particulate matter than clean air. A high concentration of particulate matter results in the death of some alveolar epithelium cells.

  If alveolar epithelium cells die inside the human body they are replaced by non-specialised, thickened tissue.

  Explain why death of alveolar epithelium cells reduces gas exchange in human lungs

  Thick wall - reduces the rate of diffusion - reducing gas exchange

  Reduced SA - reducing gas exchange
• What are the 4 main parts of the human gas exchange system?

  Trachea

  Bronchi

  Alveoli

  Diaphragm
• What does the trachea split into?

  Bronchi
• What is the role of the trachea, bronchi and bronchioles?

  To remove air
• What is the role of the alveoli?

  Gas exchange
• How is the human gas exchange system adapted for gas exchange?

  Thin walls - decrease length of diffusion path - increased rate of respiration

  Millions of alveoli - increased surface area - increased rate of respiration

  A continuous blood flow - maintaining a concentration gradient - increased rate of respiration

  Narrow capillaries - shortens the diffusion path and and slows the rate of blood flow, allowing complete saturation - effective rate of diffusion
• Why is inspiration an active process but expiration a passive process?

  Inspiration requires the diaphragm to contract, requiring energy

  Expiration allows the diaphragm to relax, not requiring energy
• Describe the process of inspiration.

  The diaphragm contracts

  External intercoastal muscles contract, moving the ribcage up and out

  Increasing the volume of the thorax

  Decreases the pressure of the thorax and pulmenaries

  A pressure gradient is created allowing air to move in
• Describe the process of expiration.

  Diaphragm relaxes

  Internal intercoastal muscles contract moving the ribcage down and in

  Decreases the volume of the thorax

  Increasing the pressure of the thorax and pulmonary

  Concentration gradient is now too high and air is forced out
• What is boyles law?

  Pressure and volume are indirectly proportional. Making a pressure gradient.