Exchange surfaces - 3 Flashcards
Why do larger organisms require exchange surfaces
Diffusion is:
- Too slow
- The distance is too great for cells far from the
surface
- Small surface area to volume ratio
Larger organisms have a higher metabolic demand
What makes an efficient exchange surface
Large surface area
Thin barrier to reduce diffusion distance
Steep concentration gradient
How are the lungs adapted for gas exchanger
Contain many alveoli which create a large surface area for for gas exchange
Alveolar walls are one cell thick which provide a thin barrier to reduce diffusion distance
Lots of capillaries which provide a blood supply to maintain a steep concentration gradient
Moist, which allows gases to dissolve
What happens during Inhalation
Diaphragm contracts and moves down
External intercostal muscles contract and move ribs up and out
Internal intercostal muscles relax
Volume of chest increases
Pressure in the lungs decrease
What happens during exhalation
Diaphragm relaxes and moves upwards
External intercostal muscles relax so ribs move down and in
Volume in chest decreases
Pressure in the lungs increase
What tissues are found in the lungs
Cartilage
Smooth muscle
Elastic fibres
Goblet cells
Ciliated cells
Squamous epithelium
What is the function of cartilage in the lungs
Prevents the collapse and bursting of the trachea during pressure changes in ventilation
Flexible so you can move your neck
What is the function of smooth muscle in the lungs
Can stretch and recoil to maintain the diameter of the airways
What is the function of elastic fibres in the lungs
Stretches when breathing in to prevent bursting
Recoils when breathing out to help push air out of the lungs
What is the function of goblet cells in the lungs
Secrete mucus which is sticky and collects particles of dust and bacteria
What is the function of the ciliated epithelium in the lungs
wafts mucus up the airways towards the mouth
What is the function of the squamous epithelium in the lungs
provides a short diffusion distance for oxygen and carbon dioxide to diffuse across
What is the vital capacity
Maximum volume of air that can be inhaled or exhaled in one breath
What is tidal volume
Volume of air that is exhaled or inhaled in one breath at rest
what is residual volume
Volume of air left in the lungs after hardest possible exhalation
What is oxygen uptake
Rate of oxygen consumption
What is breathing rate
number of breaths per unit of time
What precautions should you take when using a spirometer
Have enough oxygen in the chamber
Disinfect the mouthpiece
Use a nose clip
Have a counterbalance
Why should the student use a nose clip when using the spirometer
To ensure that all the air breathed in and out is from the chamber
Which allows for accurate results
What chemical should be used to remove the CO2
Soda lime
How does ventilation occur in bony fish
The fish opens its mouth and lowers the floor of the buccal cavity
Volume of buccal cavity increases, pressure decreases and water enters the mouth
Fish closes its mouth, floor of buccal cavity rises, volume decreases, pressure increase and water is forced out across gill filaments
Operculum forced to open and water leaves the gills
How are the gills adapted for gas exchange
Each gill is made up of many gill filaments which provide a large surface area.
each gill filament is covered with many gill plates which provide a large surface area
Gill plates have lots of capillaries which provide blood to maintain a steep concentration gradient
Thin cell walls to provide a short diffusion distance
Counter current system which ensures that a steep concentration gradient is maintained
How to dissect the gills of a fish
Push back the operculum and use scissors to carefully remove the gills
Cut each gill arch through the bone at the top and bottom
