Thank you for using Just Answer. What you may be seeing, could be blood that has clotted in your colon prior to being expelled. Passing blood in your stool is abnormal and could indicate serious health problems. You should report these symptoms to your physican and be referred to a gastroenterologist for examination. If your bleeding persists or increases, or if you experience light headedness or dizziness, this could indicate significant blood loss. You should call 911 if this occurrs.
Here is a web page with more information on GI bleeding.
I hope you find this information helpful. Please let me know if I can be of any further assistance.
The only thing I could suggest is that you take a stool sample to your physician and have it analyzed. You could have a parasite or a worm that could resemble tissue. Your diet could have profound effects on how your stool looks. Intestinal disorders causing malabsorption can affect the consitency of your bowel movements as well. But again I would like to emphasize that blood in your stool is abnormal. It could indicate ulcerative colitis or colon cancer. Without propper examination of your stool and colon, there is no way to determine for sure what you are seeing in your bowel movements.
I hope this answers your question more thoroughly. Please feel free to contact me again if I can be of any further assistance.