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