In addition to myosin, what other protein is involved in skeletal muscle contraction? O A. collagen O B. actin о C. АТР O D. keratin​

Actin.

The myosin and actin filaments are the 2 protein filament types involved in the sliding filament theory of muscle contraction.

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.

answer; ///(b) it is composed of four protein chains and four heme groups;