The human body is made up of three types of muscles: skeletal, cardiac, and smooth. Only skeletal and cardiac muscles are striated and thus, contain sarcomeres. So, what exactly are sarcomeres? It’s a long story, but luckily, we have all the space in the world to explain it to you in this week’s newsletter! So, roll up your sleeves and get ready to learn about the wonderful world of how muscles contract and release and help you go about your day.
What Are Muscles Made Of?
Like all tissue in your body, muscles are made out of cells, more specifically muscle cells. And like most other specialized cells in your body, your muscle cells are responsible for producing certain types of proteins – actin and myosin. They’re both strands of protein, but myosin has a funny little head. When sprinkled with some magical cellular energy, this funny little myosin head goes from straight to bent, pulling the actin strand that it is connected to with it. And that right there is the basis of muscle contraction.
So… What’s A Sarcomere?
Muscle cells are packed with strands of actin and myosin. Yes, the cells get longer and shorter when the contraction and relaxation occur. What gives skeletal and cardiac muscles a striated texture is the way the muscle cells, and thus the actin/myosin strands in them, are layered on top of each other. The parts where actin/myosin overlap appear darker; where they don’t overlap appear lighter. This creates lines in the muscles that we can see with the naked eye. A sarcomere is one of these dark/light banded units of striated muscle tissue.
What About Smooth Muscle?
While smooth muscle is also composed of muscle cells that contain actin and myosin, the cells aren’t layered in the same way that skeletal and cardiac muscles are. The actin and myosin strands do contract, but without the layering, we don’t see the dark and light bands in the tissue. Hence the name. Smooth muscles are found in your intestines as well as in your blood vessels. When you hear doctors say that blood vessels dilate or contract, those are the smooth muscles that make the vessels dilate and contract.
Flex Those Sarcomeres!
Got a friend who loves weightlifting? Know someone who rock climbs, runs, plays soccer, or does some sort of sport-thing? Well, our sarcomere necklace makes a great gift for these active people! Not only is it scientifically accurate, but it also perfectly sums up what gives athletes and movers the power to do the sports that they love. This piece is also perfect for physical therapists, massage therapists, doctors, and starry-eyed pre-med students who are interested in sports medicine.
written by Science with Evie