3.2 Gas Exchange Flashcards
what do efficient exchange surfaces have
1 - large SA
2 - short diffusion distance
3 - high concentration gradient
efficient exchange surfaces in single celled organisms
1 - long and flat cells
2 - long and flat cells
3 - oxygen quickly used in respiration
efficient exchange surfaces in mammal alveoli
1 - large number of alveoli
2 - alveoli/capillary walls are one flattened cell thick
3 - constant flow of blood through capillary network
efficient exchange in fish - gill filaments and lamellae
1 - lots of gill filament and lamellae
2 - thin lamellae with lots of capillaries
3 - counter-current mechanism
what is a counter-current mechanism
- Water and blood flow in opposite directions
- Maintains a concentration gradient from water to blood along the entire length of the gill
efficient exchange surfaces in insect tracheal systems
1 - trachea and tracheoles are branched and end in cells
2 - when anaerobic respiration occurs water moves out of tracheoles due to osmosis, reducing diff. distance, many spiracles
3 - active insects ventilate tracheal system by using muscles to create pumping movement for ventilation
efficient exchange surfaces in dicotyledonous plants
1 - large SA of cells exposed in spongy mesophyll due to air spaces
2 - many stomata, thin leaves
3 - CO2 quickly used in photosynthesis
what occurs during inhalation
Diaphragm contracts and flattens
External intercostal muscles contract and internal intercostal muscles relax
Ribcage moves up and out
Volume in thoracic cavity increases
Pressure decreases to below atmospheric pressure
Air moves down pressure gradient into the lungs
what occurs during exhalation
Diaphragm relaxes and domes
Elastic recoil of lung tissue
External intercostal muscles relax and internal intercostal muscles contract
Moving ribcage down and in
Volume in thoracic cavity decreases
Pressure increases to above atmospheric pressure
Air moves down pressure gradient and out of the lungs
what does a spirometer trace look like
why does water loss need to be reduced in organisms
range of vital functions within an organisms and extreme water loss can lead to death
what are adaptations in insects that reduce water loss
- exoskeleton made of chitin with waxy coating
- sphincter muscle around trachea at spiracle
- spiracle in a pit
- spiracle surrounded by hairs
how does an exoskeleton and waxy coating reduce water loss
waterproof, preventing evaporation of water vapour from surface of the insect
how does the sphincter muscle around trachea reduce water loss
contracts to close spiracle, preventing diffusion of water vapour into air
how does the spiracle in a pit reduce water loss
traps a layer of still air which is saturated with water vapour
how does surrounding the spiracle with hairs reduce water loss
traps a layer of still air which is saturated with water vapour
what are adaptations in xerophytic plants that reduce water loss
- waxy cuticle
- needle-like or small leaves
- stomata in a pit
- stomata surrounded by hairs
- rolled leaves with stomata inside
how does a waxy cuticle reduce water loss
increases diffusion distance
how do needle-like/small leaves reduce water loss
reduces surface area so fewer stomata present, decreases diffusion
how does having stomata in a pit reduce water loss
- reduces air flow over the stomata so water vapour builds up, reducing conc. gradient
how does surrounding stomata in hairs reduce water loss
traps a layer of still air which is saturated with water vapour
how does rolled leaves reduce water loss
reduces air flow over the stomata so water vapour builds up near stomata, reducing conc. gradient
