Topic 3 - Gas exchange Flashcards
(20 cards)
How does inspiration occur in humans?
- Active
-external intercostal muscles contract
-internal intercostal muscles relax
-diaphragm contracts and flattens and moves downwards
-ribs move up and outwards
-volume of thorax increased - reduces pressure in lungs
- air pressure in atmosphere > air pressure in lungs
- so forced to inhale
How does expiration occur in humans?
- largely passive
- external intercostal muscles relax
- internal intercostal muscles contract
-diaphram relaxes and becomes domed
-ribs move inwards and downwards
-volume of thorax decreases - increased pressure in lungs
-atmospheric pressure < the pressure in the lungs - so forced to exhale
Describe and explain one feature of alveolar epithelium that makes the epithelium well adapted as a surface for gas exchange ( not surface area or moisture )
- single layer of cells
- short diffusion distance
- quicker gas exchange
What is tidal volume?
Volume of air inhaled and exhaled during a single breath when a person is resting.
How does a reduced tidal volume affect age exchange of CO2 between blood and alveoli?
-Less exchange of CO2 bc less CO2 exhaled
- so reduced diffusion between blood + alveoli
- slower movement of CO2 out of blood
How is fish gas exchange more efficient than human gas exchange? ( may refer to graph)
- in fish blood leaving has more O2 than water leaving
- but in humans blood leaving has less O2 than air leaving system.
How does the counter-current principle allow efficient oxygen uptake in the fish gas exchange system?
- blood + water flow in opposite directions
- so O2 conc gradient maintained throughout
- O2 can be uptaken across full length of gills
Iodine solution stains starch a blue/ black colour. Why would iodine solution not be an appropriate choice to stain lung tissue?
Lungs don’t contain starch
Other dye better suited to make nucleus visible
Table with probabilities of risk factors being associated with named issue. Evaluate whether they are all linked.
- which are / are not statistically significant
- which is most significant
Why does the death of alveolar epithelium cells reduce gas exchange in the human lungs?
- reduces SA
- increased distance for diffusion
- therefore reduces rate of gas exchange in lungs
What is the advantage of the counter-current principle gas exchange in fish?
- Oxygen gradient maintained across the full length of the gill
- because blood and oxygenated water flow in opposite directions
- so oxygen diffuses into the fish’s blood along the full length of the lamellae
- because blood is always passing water that has a higher O2 conc
What’s one way leaf growth in xerophytic plants wicked be different from the leaf growth of sunflowers (or other named flower).
- slow growth
- due to smaller no. of stomata for gas exchange
Why do plants grow slow in soil with little water? ( with regards to gas exchange in leaves )
- stomata close due to minimising water loss
- less CO2 uptakes by diffusion through stomata
- less photosynthesis so slower growth
Describe the pathway taken by an O2 molecule from an alveolus to the blood
- diffuses across alveolar epithelium
- then diffuses across the epithelium of the capillary into the blood stream
Explain one feature of an alveolus that allows for efficient gas exchange.
- one cell thick
- short diffusion pathway
Use info provided in graph to evaluate dangerousness of named chemical in open vs closed spaces.
- is it dangerous even in low concs (any is dangerous)
- is it higher levels in open or closed
- do you have data on if that level of conc is dangerous
- is there data on the factor its affecting (eg. breathing rate0
What is the gross structure of the human gas exchange system?
- trachea, bronchi, bronchioles, alveoli
Give three ways insects tracheal system is adapted for efficient gas exchange
- tracheoles thin walls so short diffusion distance to cells.
- highly branched tracheoles so short diffusion distance to cells
- highly branched tracheoles so large SA for gas exchange
Explain how larvae (eggs laid in water) that have gills help adapt the larvae to their way of life
- higher metabolic rate so uses more O2
Two ways that the structure of fish gills is adapted for efficient gas exchange.
- many lamellae which inc SA for gas exchange
- thin, so short diffusion distance
