Adaptations in gas exchange Flashcards
What are the blood vessels connecting to the alveoli (1)
- to the alveoli - pulmonary artery
- away from the alveoli - pulmonary vein
State two important structural features of the alveoli (2)
- the alveoli in one cell thick
- large surface area / highly folded
- large number of capillaries
Briefly explain how inspiration is brought about (2)
- contraction of intercostal muscles and diaphragm
- ribcage moves up ant out
- diaphragm flatter / contract
- increase volume and decreased pressure so air moves into lungs
Describe three features of fish gills which allow them to achieve efficient fas exchange (3)
- large surface area
- short diffusion pathway
- permeable
- good blood supply
Explain how bony fish have overcome the problems of oxygen uptake in water (4)
- water is forced over the gill by continous sswimming
- counter current flow of blood and water
- diffusiongradient is maintaines
- over the entire gill surface
- haemoglobin has a high affinity for oxygen
Explain why large mult cellular organisms have evolved special surfaces for gaseous exchange (3)
- metabolic needs
- large organisms need more oxygen
- external surfae insufficieint for gas exchange
- diffusion is proportional to surface area
- surface area to volume ration is to small
- diffusion distances are too larfe
- oxygen cannot diffuse fast enough
Describe and explain how terrestrial mammals are adapated for gas exchange in air (7)
- large number of alveoli to increase surface area
- internal lungs
- to reduce heat loss
- thin walls reduce diffusion ditance
- gas exchange takes plac in the alveoli
- kayer of moisture - to allow gases todissolve
- good blood supply maintain concentration gradient
- haemoglobin in bloood transports oxygen
- ventilation mechanism
- enable continuous exchange of gases
Describe and explain the process of inspiration in a mammal (4)
- intercostal muscles contract aand ribs move up and out
- diaphragm contract and flattens
- volume of thorax increases
- pressure in lungs decreases
- higher air presure outside draws air into lungs
Explain how counter current flow works in the gills of bony fish (4)
- blood flows across gills in opposite direction to water
- water always has more oxygen than blood
- so concentration gradient is maintained
- oxygen passes from water into blood
- across entire gas exchange surface
Name the type of flow when percentage saturation with oxygen reaches equilibrium (1)
parallel flow
Explain why parallel flow is less efficient than counter current flow (2)
- equilibrium is reached part way across fill lamellae and gradient is not maintained
- percentage saturation can only reach 50% / equilibrium
Suggest why gill filaments/ gill laemellae would not provide and efficient gas exchange surface on land (2)
- gills dry out
- prevent oxygen from dissolving on surface of gills
- gillss may collape decreasing surface area
Describe three properties that all respiratory surfaces must possess and explain why they must have them (3)
- thin - short diffusion pathway
- large ssurface area - for gas exchange / diffusion
- moist - allow gases to dissolve
- permeable - tp allow gases to pass through
Suggest how this frog carries out gas exhcange wihtout lungs (1)
Through the skin
How do the conditions in the moutnain stream aid gas exchange (2)
- fast flowing
- maintains a concentration gradient
- absorbs more oxygen
