SA:V and gas exchange Flashcards
(47 cards)
-examples of specialised exchange surface
-lungs
-gill
-lamellae of fish gills,
-tracheoles of insects;
-microvilli;
-state the relationship between the size of an organism or structure and
its surface area to volume ratio.
the larger an organism, the smaller the surface area to volume ratio.
the smaller an organisms the larger the surface area to volume ratio.
-why do large organisms have small SA:V ratio
-Rate of diffusion of substances from the body into the environment via skin is reduced.
This includes heat, so large animals loose heat slowly in cold climates.
Thus having lower metabolic rate.
-why do small organisms have large SA:V ratio
-Rate of diffusion across skin is increased so small animals lose heat more rapidly in hot climates.
-They have higher metabolic rate as more heat is generated and more heat is lost.
-What changes are made to the body shape and the development of systems in larger organisms as adaptations that facilitate exchange as this ration reduces?
-Thin membrane : short diffusion pathway ensures that materials can cross the exchange surface rapidly
-Partially permeable: only allows certain materials to pass through
-Movement of the internal and external environment: ensures concentration gradient is maintained.
-Large SA:V ratio: ensure maximum rate of reaction
-Adaptations of gas exchange surfaces across the body surface of single celled organism
-Large SA:V ratio
-Oxygen is absorbed by diffusion across their cell-surface membrane
-Carbon dioxide diffuses across body surface.
-Name structure through which gases enter and leave the body of an insect
Spiracles
-Name the small tubes that carry gases directly to and from cells of an insect
Tracheole
-three ways of moving gases in the tracheal system
1) Gas exchange by diffusion, as when cells respire, they use up oxygen + produce carbon dioxide, creating a conc gradient from the tracheols to the atmosphere
2) Insects contract and relaxes their abdominal muscles to move gases on mass
3) when the insect is in flight the muscle starts to respire anaerobically to produce lactate.
This lowers the water potential of the cells and therefore water moves from the tracheoles into the cell via osmosis
This decreases the volume in the tracheoles and as a result more air from the atmosphere is draw in
-Structural and functional compromises between the opposing
needs for efficient gas exchange and the limitation of water loss
shown by terrestrial insects
-when terrestial insects have their spiracles open they lose water vapour. This is important to minimise to prevent dessication
-so insects open and close their spiracles as required rather than keeping them open all the time
-they have hairs around the spiracles to trap a layer of water vapour, reducing the water vapour concentration gradient between tracheae and the atmosphere
-limitation of water loss; TERRESTRIAL INSECTS
-Insects have small SA:V where water can evaporate from
-Insects have a waterproof exoskeleton- water cannot evaporate out of their body expect spiracles
-spiracles : gases enter and water can evaporate from, can open and close to reduce water loss
-adaptations of insect’s tracheal system
1)large number of fine tracheoles -large surface area
2) walls of tracheoles are thin + short diffusion between spiracles + tracheoles -short diffusion pathway
3) use of oxygen and the production of carbon dioxide sets up steep diffusion gradients
-rate of diffusion calculated using Ficks Law
-surface area X difference in concentration
/ length of diffusion path
-gas exchange surface features
-large SA:V ratio
-short diffusion distance
- maintained a concentration gradient
-fish gill anatomy
-there are 4 layers of gills on both sides of the head
-the gills are made up of stacks of gill filament
- each gill filament is covered in gill lamellae, position at right angles to the filament
-creates a large surface area
-when fish open their mouth water rushes in and over the gills + then out through a hole in the sides of their head.
-adaptations of fish for efficient gas exchange
-large surface area to volume ratio created by many gill filaments covered in many gill lamellae
-short diffusion distance : due to a capillary network in every lamellae and very thin gill lamellae
-maintaining concentration gradient: countercurrent flow mechanism
-define countercurrent flow principle
when blood and water flow in the opposite direction over the gill filaments.
-what does countercurrent flow ensure
that a diffusion gradient is maintained across the entire length of the gill lamellae
-explain the advantage of the counter current flow (2)
1) diffusion gradient is maintained all the way across the gill lamellae
2) more oxygen will diffuse into the blood
Describe and explain the advantage of the counter current principle in gas exchange across the gill (3)
water and blood flow in opposite direction
maintains concentration gradient
across the whole length of the lamellae
-Describe and explain how the countercurrent system leads to efficient gas exchange across the gills of a fish
- Blood and water flow in opposite directions in the capillaries
- Concentration of oxygen in the blood is lower than in surrounding water, so oxygen diffuses into the blood
- Diffusion gradient maintained over full length of lamellae
The gross structure of the human gas exchange system limited to
the alveoli, bronchioles, bronchi, trachea and lungs.
Trachea - funnels the inhaled air into the lungs, while also facilitating the removal of inhaled air out of the lungs.
· Bronchi - smaller passages where air enters the lungs from the trachea.
· Bronchioles - The bronchi further divide into smaller, and smaller passages called bronchioles.
· Alveoli - thin-walled cells that are directly connected to capillaries. Oxygen are transferred down a concentration gradient from the alveoli, into the blood cells. At the same time, carbon dioxide is transferred from the blood cells to the alveoli
The essential features of the alveolar epithelium as a surface over which gas exchange takes place.
· Large surface area - many alveoli are present in the lungs with a shape that further increases surface area.
· Thin walls - alveolar walls are one cell thick providing gases with a short diffusion distance.
· Moist walls - gases dissolve in the moisture helping them to pass across the gas exchange surface.
· Permeable walls - allow gases to pass through.
· Extensive blood supply - ensuring oxygen rich blood is taken away from the lungs and carbon dioxide rich blood is taken to the lungs.
· A large diffusion gradient - breathing ensures that the oxygen concentration in the alveoli is higher than in the capillaries so oxygen moves
ventilation
ventilation is movement of air in and out of the lungs caused by muscles an active process involves mass flow & flow along air passages;
