There are three types of muscle that we eat.
Skeletal muscle is used for barbequed meat and steaks, cardiac muscle makes up the heart, and smooth muscle is eaten as in motsu nabe (hotchpotch) and gizzards (sunazuri) yakitori (grilled chicken). Compared to skeletal muscle, smooth muscle is of limited use, and livestock by-products are treated as animal waste.
When comparing skeletal and smooth muscle at the cellular level, many proteins are similar. Smooth muscle has inherently greater potential value as a meat source, as proteins release flavorful amino acids when broken down. Biologically, smooth muscle has a vital role not only in the digestive tract, but also in blood vessels, uterus, lungs, etc. At first glance, the gastrointestinal tract is a single tube that physically joins together, but it is a complex group of organs composed of multiple organs from the esophagus to the rectum. The smooth muscle layer is responsible for contraction and peristalsis, which is the common and most important function of all gastrointestinal organs. Smooth muscle cells, which are arranged in an annulus covering the secretory cell layer of the lumen of the digestive tract, contract in a coordinated and sustained manner to ensure smooth digestion, absorption, and expulsion of unwanted substances. No one, from infants to adults, has ever experienced gastrointestinal problems such as lethargy, constipation, diarrhea, stress ulcers, and cancer due to poor food digestion and absorption. Despite their important role, it is still unclear how smooth muscle cells develop and are maintained until the end of life. In the Animal Life Science Laboratory, we are using the chick embryo myogastrium as a model to elucidate the mechanism of smooth muscle cell development and differentiation.
