3.2 Gas exchange Flashcards
What is Fick’s Law?
Rate of diffusion = S.A x Conc. gradient / Membrane thickness
Describe the counter-current system in fish
- Water passes over gills
- Blood capillaries in lamellae flow in opposite direction to direction of water
- Maintains a large concentration gradient between O2 in water and blood
- i.e conc. in blood always lower than that in water
Describe the gill structure
Gill composed of thin filaments = gill filaments
Gill filaments covered with tiny structures called lamellae
How do insects maintain flow of air in spiracles?
Rhythmic abdominal movements
Describe how air moves to get to respiring cells in an insect
Through pores in the insect exoskeleton called spiracles
Into microscopic air filled pipes called trachea
Which branch into smaller tracheoles
Tracheoles border individual cells and have thin permeable walls
What are the key features of tracheoles?
Thin, permeable walls
Describe adaptations of xerophytic plants
- Stomata sunk in pits
- Layers of hair on lower epidermis
- Curled leaves
- Reduced stomata numbers
- Thicker waxy cuticles
Why do xerophytic plants trap air around stomata
Trap moisture in air around stomata
Decrease conc. gradient of water between leaf and air
Divisions of human respiratory system
Trachea - bronchi - bronchioles - alveoli
Describe the process of inspiration
Inspiration is air moving into the lungs
- External intercostal muscles and diaphragm contract - Diaphragm flattens
- Ribcage moves up and out
- Increases volume of thoracic cavity
Is inspiration an active process?
Yes - requires energy unlike expiration
Describe adaptations of insects to reduce water loss
- Closed spiracles when dehydrated
- Waterproof waxy cuticle around spiracles and on body to reduce evaporation
What are spiracles?
Pores in an insects exoskeleton
What are trachea in insects?
Microscopic air filled pipes
