Describe some of the benefits of having a healthy normal flora in the large intestines?

The intestine is divided into two parts:
Large and Small. The Small
Intestine is what we think of when we hear the word
intestine: a collection of looped tubes, passing feces to the anus.
However, the Small Intestine is actually at the top of the chain; it connects to the
Stomach and passes food along while digesting fats, proteins, and carbohydrates. The
Large Intestine has a larger diameter but is shorter, and absorbs
vitamins and water while compacting wasted into the rectum, where it waits for
extrection. Both intestines are lined with powerful muscles that move material along by
Peristalsis, or muscle contration in
series.

Intestinal Flora are the
largest collection of cells in the body. Composed primarily of
Anaerobes, or non-oxygen-using cells, Intestinal Flora is
responsible for breaking down and releasing parts of food and nutrients that cannot be
harvested by the stomach flora. In the Large Intestine, the flora is mainly involved in
breaking down undigested fiber, releasing and producing vitamins, and creating
Cross-Reactive Antibodies, which protect the vulnurable anal
opening against outside infection. Without these flora, fiber would continue to the
rectum and cause constipation, vitamins would be excreted with waste instead of
absorbed, and any bacteria entering the body via the anus would be able to attack from
inside.

Intestinal Flora is difficult to culture and as a
result not all species have been identified. They are an example of Friendly
Bacteria living in symbiosis inside the human body. Antibiotics and
chemotherapy can inadvertantly kill off large quantities of Intestinal Flora, leaving
the body open to digestion issues and infection.