Today we had lungs to dissect. The students are always amazed at how they inflate to three times the size. It is quite something to watch, and a bit daredevil to try yourself by inserting a rubber tube into the bronchi. ( Tips: 1. it can be a two person job to hold the lungs and the rubber tubing, you really want to keep the end you put in your mouth well away from the specimen! 2. Hold the lungs up high the try to ensure there are no blockages in the bronchi or bronchioles by being folded. 3. Make sure you only blow out and immediately move you head away so that you don't get 'exhaled', or splattered, all over.
We took some time to look at the features of a gaseous exchange surface as exemplified by the lungs: large surface area everyone expects. Moist? Most students forget that gases dissolve in water and thus diffuse across exchange surfaces quicker.
To me, the most interesting thing is the role of the diaphragm. Here we are holding it up to show how tough the tissue is (like the skin of a drum) and how it attaches to the inner wall to form a complete seal of the thoracic cavity. How contraction of the muscle, seen here, pulls it flatter, thus increasing the volume in the chamber, decreasing the pressure, and causing inhalation as air is drawn in down a pressure gradient.
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Dissection Club started again today for the new academic year, and we were again treated to a pluck. Students were very interested to see the relative sizes and positions of the heart and lungs, as well as the differences in the density of the tissue
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