Exchange and Transport (complete) Flashcards
Describe the three ways in which respiratory gases move in and out of the tracheal system in insects.
Along a diffusion gradient - O2 used during respiration creates lower conc at tracheole ends, forming a diffusion gradient for gases from the atmosphere to diffuse to the cells. CO2 released during respiration creates diffusion gradient in opposite direction, allowing CO2 to diffuse from cells to atmosphere along the trachea.
Mass Transport - muscle contractions or insects squeeze the trachea which enables mass movement of air in and out which speeds up the exchange of respiratory gases.
Tracheole ends filled with gas instead of water - lactic acid produced during exercise (anaerobic respiration) in surrounding muscle cells. Lactic acid being soluble reduced the water potential of the muscle cells, drawing water into the cells from the tracheoles by osmosis, in turn drawing air in from opposite end of tracheoles. This forms a gaseous final diffusion pathway (as opposed to liquid), allowing for increased rate of diffusion.
Give Fick’s Law.
Rate of diffusion is proportional to: (surface area x concentration difference) / distance
How are insects adapted to conserve water?
Water conservation -
- Small surface area : volume ratio to minimise water loss from body surface.
- Waterproof coverings on skin/exoskeleton.
- Spiracles can be closed to prevent water loss.
Describe the anatomy of insects for gas exchange.
- Each segment of the insect (other the head) contains a pair of lip-like openings called spiracles.
- Tracheal tubes are connected to each spiracle branch into a series of tracheoles.
- Tracheoles repeatedly divide until their numerous microscopic ends penetrate into individual body cells.
How are insects adapted to gas exchange?
Gas exchange -
- Many tracheal (connected to many spiracle openings): allows for many openings to be available for more gas exchange through the body surface.
- Many tracheole (that are highly branched with thin walls): allows for shorter diffusion pathways to tissues/cells due to increased surface area and thin walls.
- Each tracheole connects to an individual cell: allows for transport of the respiratory gases to and from each cell along a short diffusion pathway.
- Abdominal pumping: squeezes the trachea enabling mass movement of air in and out to increase rate of gas exchange by maintaining a concentration gradient.
- Lactic acid and water potential changes: allows for diffusion through the gas phase rather than liquid phase (which is slower) due to lactic acid production in anaerobic respiration causing a decrease in water potential in the respiring muscle cells as lactic acid is soluble. This causes water to be drawn into the muscle cells, filling the tracheole ends with air instead.
Describe the effect of surface area to volume ratio on gas exchange.
- The larger the surface area to volume ratio, the easier efficient exchange of gases can occur.
Describe the adaptations of a leaf for gas exchange.
- Many Stomata - found on the bottom of the leaf to recent water loss, and can be opened by guard cells to increased gas exchange through them.
- Leaves are very thin - allows for short diffusion pathways between cells and atmosphere for increased gas exchange.
- Wide leaves surface - increase the surface area of the leaf to increase rate of gas exchange by diffusion.
- Interconnecting air spaces in the mesophyll - allows space for gases to diffuse through to reach or leave a cell.
Describe some similarities and differences between gas exchange in insects vs plants.
Similarities -
- Both contain many pores in outer coverings (spiracles/stomata) which open and close to increase gas exchange/reduce water loss.
- Both use gas phase diffusion rather than liquid.
- Both have short diffusion distance between external air and cells.
Differences -
- Insects have trachea for the respiratory gases to diffuse along, while plants don’t.
- Plants have stomata, insects have spiracles.
- Insects create mass air flow to assist gas exchange.
- Plants interchange gases between respiration and photosynthesis, and have larger SA:V ratio than insects.
Name some adaptations for Xerophytes to obtain water/reduce water loss.
- Small leaf surface area - minimises area for evaporation to reduce water loss.
- Low stomata density - fewer gaps in leaves to minimise evaporation.
- Stomata on lower surface of leaf only - less direct sunlight, and more humid air to reduce evaporation.
- Sunken stomata - maintains presence of humid air around the stomata to keep small water potential gradient to reduce evaporation.
- Stomatal hairs - helps maintain humid air around the stomata to reduce water potential gradient for reduced evaporation.
- Thick cuticle - prevents uncontrolled evaporation through leaf cells.
- Shedding leaves in dry/cold season - reduces water loss through leaves at certain times of the year.
- Folded leaves - maintains humid environment environment around the stomata to reduce evaporation.
- Succulent leaves and stem - place to store water when there is plentiful available to use when there is minimal available.
- Extensive roots - allows plant to find more water by branching out further to allow for deeper water to be absorbed.
Describe the structure of the human lungs, and the function of each part.
- Trachea - airway for intake of 02 and release of C02. Supported by rings of cartilage which prevent the trachea collapsing as pressure falls. Tracheal walls made up of muscle , lined with ciliated epithelial cells (sweep mucus) and goblet cells (form mucus)
- Bronchus - the two divisions of the trachea, lined with ciliated epithelial cells and muscle cells, which produce mucus to trap dust particles. The larger bronchus are supported by cartilage, which gradually reduces in amount as the bronchus get smaller when branching.
- Bronchioles - branching subdivisions of the bronchi. The walls are made up of muscle lined with epithelial cells. The muscle allows them to construct to control air flow.
- Alveolus - Air sacs at the ends of the bronchioles, which contain collagen and elastic fibres (stretch and recoil to help ventilate air space) between the alveoli. The alveoli are lined with epithelial cells.
Describe the adaptations of alveoli for gas exchange.
- Pulmonary capillaries - very thin so slow the blood cells down to allow for more time for diffusion, and providing a constant flow of blood to maintain a concentration gradient.
- Thin alveoli and pulmonary capillary walls - creates a very short diffusion pathway for the gases to diffuse across.
- Many pulmonary capillaries and alveoli - creates a very large total surface area to increase diffusion.
Describe the adaptations of fish gills for gas exchange.
- Thin fish gills - increased surface area ad shorter diffusion pathways.
- Many lamellae found on many gill filaments - the lamellae are only a few cells thick allowing for a shorter diffusion pathway and increased surface area.
- ‘Counter-current flow’ - opposing directions of water and blood flow in gill filaments. Blood is always coming into contact with water with a higher dissolved oxygen concentration, allowing for efficient transfer of oxygen due to maintenance of downward concentration gradient for oxygen along the whole lamellae length.
Describe how the Counter Current flow in fish is efficient.
- if blood flow and water was parallel, as oxygen diffused into the blood, eventually the concentrations would be equal in the blood and water. This would mean no more oxygen would diffuse into the blood without the use of energy.
- as the flows are opposite, and the water flows past the capillaries, the concentration of oxygen will decrease in both the water and blood maintaining a downward concentration, allowing for all/more of the oxygen to be absorbed by diffusion.
Describe the structure of the gills in fish in terms of gas exchange.
- Gills are the gas exchange surfaces in fish, composed of gill filaments which are stacked together.
- Gill lamellae project at right angles from the filaments, and help increase the surface area of the gills for gas exchange.
- The gill lamellae are just a few cells thick and contain blood capillaries.
