The document summarizes the formation and defecation of feces in the large intestine. [1] Undigested food enters the colon from the ileum and moves through the ascending, transverse, and descending colon where water, salts, and vitamins are absorbed. [2] By the time the feces reach the sigmoid colon, it has become compact and dry and is stored in the rectum until defecation. [3] The anal sphincter muscle in the rectum relaxes to allow defecation of feces through the anus.

1. 6.6 FORMATION OF FAECES AND
DEFECATION

2. The Large Intestine
Sigmoid colon

3. 1.5m absorb water and
compact material in
faeces
Store faeces to
be defecated
Caecum :
A pouch with the appendix
(9cm) as an extension
Absorb vitamins Rectum = 15cm
produced by
Appendix :
Plays no part in digestion bacteria

4. FORMATION OF FAECES AND DEFECATION
1. Undigested food comes from ileum into the
colon consists of indigestible materials
(cellulose) and liquid.
2. Undigested food goes …….>>
ASCENDING COLON  TRANSVERSE COLON  DESCENDING COLON
1. WATER!!! SALTS!!! and VITAMINS!!! are
absorbed into the colon, and the remaining
contents in the lumen becomes faeces.

5. 3. By the time faeces reach the sigmoid colon,
it is quite compact and dry.
4. The sigmoid colon is designed to slow down
the movement of faeces until is ready to be
eliminated.
5. The rectum is the lowermost segment of the
large intestine that stores the faeces.
6. The rectum has a specialised muscle, called
the anal called the anal sphinter, which
relaxes and egests (for defecates) the faeces
through the anus.

6. Defective defecation cause :
DIsChargingg Waste!! + • headache
Unwanted toxic substances!! • abdominal discomfort,
to avoid toxicity…… • poor appetite and
• sensation of vomiting
IMPORTANCE OF THE DEFECATION
If the colon retains its contents If constipation frequently
too long, the fecal matter takes place, it causes
becomes dried out and ill-health and increases the
compresses into hard risk of contracting
masses causing constipation colon cancer!!
and haemorrhoids

7. Constipation
DEFECATION
RELATED
PROBLEMS
Haemorrhoids Colon Cancer