Circular Smooth Muscles

by Greg Crowther

This jingle, originally written for Biology 241-242 and 351-352 at UW-Bothell, covers constriction and dilation in the most general way possible, so that students recognize the common principles underlying the control of flow through arterioles, bronchioles, the gastrointestinal tract, etc. In all of these cases, smooth muscle surrounding the tube contracts or relaxes to adjust the size of the lumen of the tube, thus controlling the rate of flow.

Smooth smooth muscle cells encircling a tube,
Regulating radius and thus the flow rate through.

Contraction is constriction; relaxation is dilation!
Contraction is constriction; relaxation is dilation!

Blood, air, urine, lymph, semen, bile, or chyme.
Tubes with fluid everywhere conform to this design.

Contraction is constriction; relaxation is dilation!
Contraction is constriction; relaxation is dilation!

• sheet music (with melody play-back)

Songs like this one can be used during class meetings and/or in homework assignments. Either way, the song will be most impactful if students DO something with it, as opposed to just listening.

An initial, simple follow-up activity could be to answer the study questions below. A more extensive interaction with the song might entail (A) learning to sing it, using an audio file and/or sheet music as a guide, and/or (B) illustrating it with pictures, bodily poses, and/or bodily movements. The latter activity could begin with students identifying the most important or most challenging content of the song, and deciding how to illustrate that particular content.

(1) What is chyme?

(2) Can all of the substances listed (blood, air ...) be considered fluids?

(3) Do we have voluntary control over the muscles covered in this song?

(4) Give an example of a drug that affects the degree of smooth muscle contraction and thus alters the flow through the corresponding tube.