Exchange Systems Flashcards
What two things mean diffusion alone enough for single celled organisms ?
Metabolic activity is so low that the oxygen and carbon dioxide production is quite low
Surface area to volume ratio is large
Why cant larger multi-celled organisms just rely on diffusion alone ?
The organism has a smaller surface area to volume ratio so gasses cant be exchanged fast enough for the metabolic demands as there is not a large enough diffusion surface
What 4 features do effective exchange surfaces have ?
Increased surface area
Thin layers
Good blood supply to maintain concentration gradient
Ventilation to maintain diffusion gradient
What 3 things does the naval cavity do ?
Large surface area with good blood supply warms the air to body temperature
Hairy lining secretes mucus to trap unwanted bacteria
Moist surface increases humidity of air,reducing evaporation
Why is the trachea is supported by c shaped cartilage rings ?
It stops the trachea from collapsing whilst still allowing food to move down the oesophagus
What lines the trachea and why ?
Goblet cells secrete mucus and traps microorganisms and then the ciliates epithelium cells move the mucus away from the lungs
Why are the bronchioles covered in smooth muscle ?
So that the muscle can contract and change the amount of air reaching the lungs
What do the alveoli consist of ?
Thin flattened epithelial cells
Collagen
Elastic fibres
What is elastic recoil?
Elastic tissues allow the alveoli to stretch as air is drawn in and return back to resting size to squeeze air out
How are the alveoli adapted to be good at gaseous exchange ?
Large surface area
Thin layers means short diffusion distance
Good blood supply maintains concentration gradient
Good ventilation maintains concentration gradient
How do phospholipids play a role in gas exchange ?
Phospholipids make up lung surfactant that prevents alveoli from sticking together and keeps them inflated
Why is water found in the lungs ?
Oxygen dissolves into the water making diffusion easier and quicker
What happens during inspiration ?
The diaphragm contracts and flattens
External intercostal muscles relax, causing the ribs to move upwards and outwards
Volume in thorax increases so air moves in
What happens during expiration
The diaphragm relaxes and moves upwards
The external intercostal muscles relax so the ribs move down and inwards
Volume in the thorax decreases creating pressure , so air moves out
Which process requires energy ?
Inspiration
Which process is passive ?
Expiration
How do you exhale forcibly ?
It requires energy as the internal intercostal muscles contract and pull the ribs down fast and forcing the diaphragm up to increase pressure quickly
What ways can volume of air drawn in and out of the lungs be measured ?
Peak flow meters- rate that air is expelled
Vitalographs- sophisticated version of peak flow that creates a graph
Spirometers- canister of soda lime removes carbon dioxide, lid moves up and down placed on top of water
What is tidal volume ?
The volume of air that moves in and out of the lungs with each resting breath
What is vital capacity?
The most amount of air that can be breathed in after the strongest exhalation followed by the deepest breath possible
What is inspiratory reserve volume ?
Maximum volume of air you can breath in above a normal inhalation
What is residual volume ?
The volume of air left in your lungs after exhaling as hard as possible
What is total lung capacity ?
Sum of vital capacity and residual volume
How do you measure ventilation rate ?
Tidal volume x breathing rate (per minute)
What are the small openings along the thorax and abdomen of insects called ?
Spiracles
What do sphincters do ?
Open or close spiracles to reduce water loss but allow more oxygen in when the insect is active
What comes after the spiracles ?
Trachae and then tracheoles
What are trachae lined with ?
Chitin- an impermeable material
How does oxygen reach the cells in insects ?
Tracheoles run between cells and oxygen dissolves in moisture on the walls and diffuses into cells
What does trachael fluid do and how does it help when there is a higher oxygen demand ?
It limits diffusion of oxygen into the cells, but when lactic acid builds up due to anaerobic respiration it causes the water to move out of the tracheoles by osmosis which means there is more surface for gaseous exchange
How do some insects who have high energy demands get extra oxygen ?
Mechanical ventilation - air is pumped in or out through muscular pumping, changing the pressure inside the tracheae
Collapsible enlarged tracheae or air sacs - act as air reservoirs that can increase air moved in
What do gills have that make them efficient gas exchange surfaces ?
Large surface area
Good blood supply
Thin layers
What is ram ventilation ?
Fish such as sharks and rays continually have to move to keep water moving over the gills
What does opening the mouth and buccal cavity lowering do ?
Increases the volume of the beccal cavity so water moves into it
What does opercular valve shutting and and the opercular cavity expanding do ?
Lowers the pressure in the opercular cavity containing the gills
What happens after the opercular cavity expands ?
The floor of the buccal cavity moves up so water moves over the gills
How is water finally moved over the gills ?
The mouth closes,operculum opens and the opercular cavity moves inwards , increasing pressure
The tips of adjacent gill fillaments overlap, why ?
Increases resistance to the flow of water and slows it down so there is more time for gaseous exchange
What is a parallel system ?
Blood in gills and the water flow in the same direction so a concentration gradient is only present until the blood and water reach equillibrium - 50% of oxygen is removed from the water
What is a countercurrent system ?
Blood and water flow in opposite directions so a steep concentration gradient is always maintained - 80% of oxygen is removed from the water
