Faeces: Composition and Function
Faeces can be crucial evidence in forensic investigations, particularly in cases of sexual assault, animal cruelty, and drug trafficking. The presence of faecal matter in such cases may indicate that a sexual assault involved forced anal penetration, or that animals were kept in unsanitary conditions. Forensic analysis of faecal matter can also detect the presence of drugs, poisons, or other substances, providing evidence of drug use or drug trafficking. Furthermore, determining the age of the faecal matter can help establish a timeline of events in a criminal investigation.
COMPOSITION OF FAECES
Faecal matter, also known as stool, is the solid or semisolid excretory product of animal metabolism that is eliminated from the body through the anus. Faecal matter is largely made up of water, which accounts for about 75% of its weight. The remaining 25% is made up of solid materials such as:
Undigested food particles: Some food particles may not be completely broken down by the digestive system and may be eliminated in faecal matter. Examples of undigested food particles include seeds and fibers from fruits and vegetables, as well as undigested carbohydrates such as lactose or fructose.
Intestinal cells: The lining of the intestinal tract, like any other tissue in the body, undergoes a natural turnover process where old cells are shed and replaced with new ones. This process is important for maintaining the health and proper functioning of the intestine. As the intestinal lining sheds cells, some of these cells may pass through the digestive tract and be eliminated in fecal matter. These cells can include various types of cells, such as epithelial cells, immune cells, and mucus-secreting cells.
Bacteria and other microorganisms: The intestines contain a large number of microorganisms, including bacteria, viruses, fungi, and other microbes, collectively known as the gut microbiome. These microorganisms play a crucial role in maintaining the health and proper functioning of the digestive system and the body as a whole. As faecal matter passes through the intestines and is eliminated from the body, it carries a significant amount of these bacteria and other microorganisms.
Bilirubin: Bilirubin, a yellow-orange pigment, is a byproduct of heme metabolism that occurs during the breakdown of red blood cells (RBCs). RBCs have a limited lifespan of about 120 days before they are broken down by the liver and spleen. Upon metabolism of the heme molecule in RBCs, bilirubin is formed in the liver and subsequently secreted into the small intestine as a component of bile.
Urobilin and Stercobilin: Bacteria within the small intestine facilitate the enzymatic breakdown of bilirubin, resulting in the formation of urobilinogen. Subsequently, a portion of the urobilinogen undergoes conversion into stercobilinogen. Finally, these compounds are further metabolized to form urobilin and stercobilin, respectively, which are ultimately excreted from the body through the urine or feces.
Chemicals and drugs: Certain chemicals and drugs that are ingested can be excreted in fecal matter through a process known as enteric excretion. These substances are either poorly absorbed by the intestines or are not broken down or metabolized by the liver.
Fat: The excess dietary fat may not be completely absorbed by the small intestine and end up in the large intestine. Once in the large intestine, the excess fat may combine with other waste products to form faecal matter.
Muscle fibers: The muscular layer of the intestinal wall is made up of two layers of smooth muscle that contract and relax to help mix and propel the contents of the intestine along its length. However, small amounts of these muscle fibers can sometimes be shed and passed out of the body in faecal matter.
Overall, the exact composition of faecal matter is primarily determined by the food and fluids that a person consumes, as well as the activity of the digestive system and the gut microbiome.
FUNCTIONS OF FAECES
Waste elimination: One of the primary functions of faeces is the elimination of waste products from the body such as undigested food particles, bacteria, fiber, chemicals, drugs, etc. The faeces are eliminated through the rectum and anus, usually in the form of solid or semisolid matter. This process of eliminating waste products from the body, called excretion, is vital to maintain overall health and well-being. Failure to eliminate waste products can result in constipation, bloating, and other digestive problems, as well as the accumulation of toxins in the body.
Diagnostic tool: Faeces can be a valuable diagnostic tool for a range of health conditions. The composition and appearance of faeces can provide important clues about the functioning of the digestive system and other organs in the body.
Color changes in faeces can be an indicator of liver or gallbladder problems. For instance, dark-colored faeces may indicate the presence of blood, while light-colored faeces may suggest a lack of bile in the stool. The texture and consistency of faeces can also provide valuable diagnostic information. Hard, dry faeces can indicate constipation or dehydration, while loose, watery faeces may indicate a bacterial or viral infection.
Moreover, the presence of various substances such as blood, parasites, and pathogens, could be an indicator of underlying diseases or infections. For instance, blood in faeces could indicate various conditions such as hemorrhoids, polyps, or colorectal cancer. Parasites and other pathogens present in faecal samples can provide evidence of infection or infestation in the digestive system, which may require treatment. Therefore, by analyzing faecal samples, doctors and healthcare professionals can diagnose a range of conditions and diseases, enabling early intervention and treatment.