In Marian Diamond’s 11th Human Anatomy lecture, she talks about the three types of human muscles – smooth, cardiac and skeletal. In drawing pictures of them while taking notes, I could easily see the differences, though when looking at the slides shown at the end of the lecture it was a tad more difficult to discern which was which.
Smooth muscle surrounds our hollow organs and tubes, which are also called our viscera. Have you ever said, “I have a visceral feeling about this.” That visceral feeling is akin to a gut reaction or your intuition; you’ve probably never said “I have a visceral thinking about this.” In the center of each cell (dark oval-like shape) is the nucleus (circular shape that almost looks like blobs of water).
You do not voluntarily control your smooth muscle. For example, females who are giving birth automatically have their uterus contract. For such a powerful and important task, it may be no surprise that the largest mass of smooth muscle is in the uterus.
Another hang out for smooth muscle is in the gastrointestinal tract, where there are slow and rythmic contractions to move along food or waste through our system. And one more location for smooth muscle is in our eyes. Every time you move your eye to read these words on the screen, your pupil is moving.
Calmly have a seat and place a hand over your heart. Do you feel your heart beating? Your heart beats about 72 times per minute when sitting. Marian Diamond asked us to try an exercise – open and close one hand 72 times in a minute. Go ahead and try that now.
How did your hand feel after opening and closing 72 times? Professor Diamond suggested we now imagine our hearts beating like that every day for 80 years. You begin to appreciate how strong and determined our cardiac muscle is!
The longest muscle cell is a skeletal muscle in our thighs known as the sartorius. It is about 14 inches (35 cm) in length. Ever been described as looking sartorial? That would have been someone saying you looked quite tailored. Sartorius, Latin for “tailor”, gave its name to the muscle presumably because of how a tailor positioned himself when sitting. By the way, the shortest muscle cell is in the internal ear.
Marian Diamond gave just an introductory overview of these muscle types, but she summed it all up quite nicely by saying It’s really much more beautifully complex.
NOTE: Images of the three muscle slides above come from screen shots taken of Lecture 11, which is posted below.
@brainbits: We have 3 types of muscle tissue: smooth, cardiac & skeletal. Did you know–your heart beats about 72x/min when you’re sitting still.
@brainbits: Why specialized cardiac muscle? Open & close your hand 72x in a minute. How’s your hand feel! Imagine your heart doing this daily for 80 yrs
@brainbits: Big vocab to explain, define & locate human anatomy parts! M. Diamond says of our muscle system “It’s really much more beautifully complex.”