6.6 FORMATION OF FAECES AND DEFECATION

The Large Intestine

Sigmoid colon

1.5m

Caecum : A pouch with the appendix (9cm) as an extension

Appendix : Plays no part in digestion

absorb water and compact material in faeces

Absorb vitamins produced by bacteria

Store faeces to be defecated

Rectum = 15cm

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.

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.

• Explain the role of microorganisms in the colon & the effect of antibiotics on them.

•Synthesis of vitamin B12 & vitamin K

•Conversion of cellulose to simple sugar

•B12 : formation of rbc•K : synthesis of blood clotting factors

IMPORTANCE OF THE DEFECATION

DIsChargingg Waste!! + Unwanted toxic substances!!

to avoid toxicity……

Defective defecation cause :• headache• abdominal discomfort, • poor appetite and • sensation of vomiting

If the colon retains its contents too long, the fecal matter

becomes dried out and compresses into hard masses causing constipation and haemorrhoids

If constipation frequently takes place, it causes ill-health and increases the risk of contracting colon cancer!!

DEFECATION RELATED

PROBLEMS

Constipation

Colon CancerHaemorrhoids

CONSTIPATION• The difficulty or infrequent evacuation of the bowels (elimination of faeces).

• Faeces becomes dry & hard difficult to eliminate.

• To prevent eat foods high in fibres, drinking more fluid

HAEMORROIDS Swollen veins in the rectum

or anus.

Constipation EXCESSIVE pressure exerted on the veins.

Itchiness, pain & rectal bleeding when the veins rupture.

COLON CANCER Develops gradually.

A cell divides actively form a polyp malignant (month years later).

Symptoms : change in frequency of bowel movement, blood in faeces, abnominal pain, discomfort, weight loss.

Closely link to diet @ is hereditary.

Consume high-fibre & low fat diet.