Exchange And Trasport Systems Flashcards
Examples of substances that organisms need to exchange with environment?
. Cells need to take in oxygen for aerobic respiration and nutrients
. Excrete waste products e.g co2 and urea
. Stay at same temperature so heat needs to be exchanged too
Process of gas exchange in plants?
. Main gas exchange surface is the surface of the mesophyll cells in the leaf. They have a large surface area
. Gases move in and out through special pores in epidermis called stomata
. Stomata opens to allow gas exchange and closes if plant is loosing too much water. Guard cells control the opening and closing of stomata
Adaptations of plants to reduce water loss?
. Waxy cuticle and hairs- traps moisture to increase humidity so water potential decreases so less evaporation
. Water enters guard cells making them turgid which opens stomatal pore. If plant gets dehydrated guard cells lose water and become flaccid which closes pore
Xerophytes + their adaptations to reduce water loss ?
. Xerophytes are adapted for life in warm, dry or windy habitats
Adaptations :
. Stomata sunk in pits that trap moist air so conc gradient reduces so less h2O diffuses out of leaf
. Hairs on epidermis so trap moist air around stomata so air can’t evaporate out of stomata
. Curled leaves with stomata inside so protected from wind
. Reduced number of stomata so fewer places for water to evaporate
. Waxy cuticle so reduces evaporation
Gas exchange in fish?
Fish have a small surface area to volume ratio and have an impermeable membrane so gases can’t diffuse through their skin. So they need a specialised gas exchange surface. Bony fish have four pairs of gills and each one is supported by an arch. Along each arch there are multiple projections called gill filaments, with
lamellae on them which participate in gas exchange. Blood and water flow across the lamellae in a counter current direction (opposite directions). This ensures that a steep diffusion gradient is maintained so that the maximum amount of oxygen is
diffusing into the deoxygenated blood from the water. The projections are held apart by water flow. Therefore, in the absence of water they stick together, thus meaning fish cannot survive very long out of water.
Ventilation in fish?
required to maintain a continuous unidirectional flow. Ventilation begins with the fish opening its mouth followed by lowering the floor of buccal cavity. This enables water to flow in. Afterwards, fish closes its mouth, causing the buccal cavity floor to raise, thus
increasing the pressure. The water is forced over the gill filaments by the difference in pressure between the mouth cavity and opercular cavity. The operculum acts as a valve and pump and lets water out and pumps it in.
fish gill anatomy?
. 4 layers of gills on both sides of head
. stacks of gill filaments- each one covered in gill lamellae, positioned at right angles- creates a large SA
adaptations of fish for efficient gas exchange?
. short diffusion distance due to capillary network in every lamellae and every thin gill lamellae
. maintaining conc gradient- countercurrent flow mechanism
. large SA:Vol created by many filaments covered in many gill lamellae
countercurrent exchange principle?
. water flows over gills in opposite direction to flow of blood in capillaries
- ensures equilibrium isn’t reached
- diffusion gradient is maintained across entire length of gill lamellae
adaptations of terrestrial insects to prevent water loss?
. small SA:Vol where water can evaporate from
. waterproof exoskeleton
. spiracles. where gases scan enter and water can evap from, can open and close to reduce water loss
insect tracheal system?
. involves trachea, tracheoles, spiracles
- spiracles- round, valve like openings, running along entire length of abdomen. O2 and CO2 enter and leave via spiracles. spiracles attach to trachea
- trachea= network of internal tubes. Trachea tubes have rings within them to strengthen tubes and keep them open
- tracheoles= trachea branch into smaller tubes, deeper into abdomen of insect called tracheoles. these extend throughout all tissues in insect to deliver oxygen to all respiring cells
3 methods of moving gases in tracheal system?
. diffusion- when cells respire, they use up O2 and produce CO2, creating a conc gradient from tracheoles to atmosphere
. mass transport- insect contracts and relaxes abdominal muscles to move gases on mass
. when insects are flying, muscle cells respire anaerobically to produce lactate so lower water potential so H2O moves from tracheoles into cells by osmosis so decrease in vol in tracheoles so more air
-> to do with pressure changes
adaptations of insects for efficient diffusion?
. large number of fine tracheoles - large SA
. walls of tracheoles are thin and short distance between spiracles and tracheoles- short diffusion pathway
. use of O2 and production of CO2- conc gradient maintained
ventilation in humans?
. diaphragm- antagonistic interaction between external and internal intercostal muscles
. external intercostal muscles contract- inspiration- air moves into lungs from atm pressure to lower pressure
.internal intercostal muscles contract- expiration- rib cage pulled in and down to decrease vol in thorax so higher pressure
alveolar epithelium adaptations?
. gas exchanges between epithelium and blood
. alveoli are tiny air sacks, 300 million in each human lung so large SA for gas exchange
. epithelium cells are very thin to minimise diffusion distance
. alveolus surrounded by network of capillaries to remove exchanged gases so conc gradient maintained
