Concentric contractions: A concentric contraction is a type of muscle contraction where the length of the muscles shorten while undergoing tension. For example, when you pick up a curl bar and perform a biceps curl, the length of your biceps muscles shorten.
Here are just a few reasons why your baby may have blood in his stool: 1  An anal fissure, which is a small anal tear often caused by passing a hard stool. 2  A food allergy. 3  Maternal blood from delivery or from cracked, sore nipples.  An intestinal 1  infection. An intestinal disorder, such as colitis or intussusception.
Sometimes, the blood may not even be visible on the stool, and this is termed occult gastrointestinal bleeding. By far, the most common causes of visible blood in the stools are diverticulitis and hemorrhoids. Other conditions and situations that can cause blood in the stools include: colon cancer. non-cancerous growths, such as polyps. intestinal infections (bacterial enterocolitis) that can be caused by foodborne pathogens, such as salmonella and E. coli.