18mg for a 19-50 year old adult female.
The stem of the plant should be cut at least three to four centimeters above the surface level.
The stem should be tightly fixed into the glass capillary.
All connection should be made air-tight by using paraffin.
Initial and final readings should be carefully noted.
Increase in thoracic volume, decrease in pressure
Answer: The model, which is air tight, represents the thorax, and air is only able to enter via the glass tube which represents the trachea.
As the rubber sheet is pulled down the volume of the jar increases, the pressure therefore decreases and air is drawn in through the glass tube inflating the balloons, which represent the lungs.
There are a number of similarities and differences between the model and the actual respiratory system.
Glass tube/tracheaAllows air to pass through, splits into twoGlass is rigid and inflexible unlike the cartilage bound trachea
Bell jar/chest cavityAir tightUnable to move, the ribs can move up and out to increase the volume of the thorax
Balloons/lungsCan inflate and deflate, are elastic like the alveoliThe balloons are large open spaces whereas the lungs are made up of millions of individual elastic alveoli
Rubber sheet/diaphragmCan be domed up to decrease the volume in the jarThe diaphragm only flattens, it is not pulled downwards like the rubber sheet.
C. There <span>are</span><span> </span><span>seasons</span><span> </span><span>on Mars. </span>
