topic 4 : exchange and transport Flashcards
what is simple diffusion
passive transport, movement of substances from an area of high to low concentration. in the phospholipid bilayer, small/non-polar molecules can go through.
what is facilitated diffusion?
diffusion that takes place through carrier protein or protein channels
what is active transport
movement of substances from an area of low to high concentration (against the concentration gradient). This is helped with ATP
two types of active transport
endocytosis : movement of large molecules into the cell by fusing a vesicle with the cell surface membrane
exocytosis : movement of large molecules out of the cell by the fusing of a vesicle (which contains the substances) with the cell surface membrane (requires ATP)
describe and explain the structures of the fluid mosaic model
- phospholipid bilayer (non polar tail is away from the water)
- phospholipids can move aorund (thats why the layer is fluid)
- proteins in cell membrane (peripheral and integral)
- cholesterol : stability
peripheral proteins are used for structural purposes integral proteins used for transporting minerals
Charged particles and large particles need to be moved by what?
integral proteins
describe the process of inhalation
- interconstal muscles contract
- diaphram flattens (contract)
- volume in thorax increases
- pressure decreases lower than the atmospheric pressure
- air forced in down the conc gradient
describe the process of exhalation
- intercostal muscles relax
- diaphragm relaxes
- volume of thorax decreases
- the pressure will increase (higher than the atmospheric pressure)
- air forced out down the conc gradient
how are alveoli adapted to gas exchange
- large surface area (maximise gas exchange - short diff dist)
- thin/flat epithelial cells - short diffusion distance
- ventilation - breathing in and out will constantly remove the co2
- high capillary network : oxygenated blood constantly carried out - maintian steep conc gradient
how are insects adapted for gas exchange
- spiracles : closing the spiracles by using sphincter muscles (this controls the amt of H2O being released)
- trachae are branched (into traecheoles - increase sa:vol ration)
how do insects do gas exchange
o Spiracles are openings in the exoskeleton allowing gas exchange – the opening and closing of them are controlled by sphincter muscles to prevent water loss
o Oxygen diffuses into the spiracles, down the trachea (the trachea is lined with chitin making it impermeable preventing gas exchange here and also prevents the trachea collapsing)
o Oxygen then diffuses into tracheoles which are permeable, so gas exchange occurs here with the muscle fibres
o Sometimes water builds up at the bottom of tracheoles (dissolve the oxygen)
then the oxygen can go to the muscle fibres
what happens if there is less gas exchange in the insect
less gas exchange -> anaerobic respiration -> lactic acid builds up in the muscles
- the water potential in the muscles will be lower than in the tracheoles
- so water moves into muscles by osmosis
- then respiration/gas exchange will resume as normal
how do fish adapt to gas exchange
lamellae : thin branches - large surface area and small diffusion distance (have rich blood supply -> maintain conc grad)
countercurrent flow : maintain steep conc grad , blood flows in opposite directions- blood always meets water that has a high conc in o2
overlapping gill filaments - slow down flow of water (more time for gas exchange)
how do fish do gas exchange
o Gills are made up of filaments called lamellae – water continuously moves over the gills keeping them spread out to increase the SA and also prevent the gills sticking together
o Floor of the mouth opens the operculum (gill flap) closes
o The mouth will close and this causes the floor of the mouth to raise and increase the pressure
o The increased pressure will force open the operculum and water is forced over the gills
o Countercurrent exchange system: blood and water flow in opposite direction to maintain the steep conc gradient over the entire gill filament
how do plants do gas exchange
when conditions are favorable for photosynthesis, K+ ions move into the guard cells by active transport
- this makes water move into the guard cells by osmosis
- arrangement of cellulose in cell wall results in bending of guard cells (stomata opens) [the inner wall is rigid and it resists the expansion, so they become curved]
when conditions not favourable, K+ ions are move out of guard cells -> water leaves by osmosis, guard cell becomes flaccid
how do plants adapt for gas exchange
(normal plants and woody plants)
- leaves provide a large surface area
- spongy mesophyll cells are irregularly shaped (large surface are) and have thin walls (small diffusion distance)
- walls of mesophyll are moist (so they can absorb their necessary gases)
- stomata :
in woody plants :
- loosely arranged cells with air spaces
- they link the inner tissues of woody structures like tree trunks to the outside so that respiration can take place.
- they can also form roots for G.E with the soil
what is a double circulatory system
blood goes through the heart two times
what are the advantages of having a double circulatory system
- oxygenated and deoxygenated blood dont mix and maintains conc grad
- blood pressure to body tissues is higher
- blood pressure to lungs is lower, this increases the time for gas exchange [avoid damage to the capillaries]
- organisms can have larger bodies
what is systematic circulation
oxygenated blood to tissues, then return deoxygenated blood to the heart
what is pulmonary circulaton
circuit between heart and lungs - lower pressure due to capillaries
what does the atrioventricular valve do
bicuspid (left) and tricuspid (right) prevent the backflow into the atria
what do the semilunar valves do
separate artieries from ventricles (where blood leaves the heart from)
what do the tendinous chords do (is attached to the AV valves)
prevent AV valves turning inside out due to pressure
what does the septum help with
it prevents the mixing of blood because it separates the right and left side
