What moves out of the gut?

Two major pathways of waste expulsion are shown above. Which of the two do you think happens exclusively through the gut? Imagine you made a roll by wrapping a hand full of left over tea leaves in a tissue paper. Later you press the roll gently and open it. What did you observe? You find the tissue paper had absorbed the water from the tea leaves.

Similarly when the unwanted waste material (stools / faeces) reach the large intestine. The peristaltic waves move the stool into the rectum. The left side of the colon acts like a storage tank of faeces. Water gets reabsorbed and the remaining wastes usually hard mass gets stored in the last part (Rectum) of the large intestine. This smelly yellowish faecal matter usually called as stool is later expelled out of the body through the anus.

What controls the exit of stools from the body?

Do you think the control is voluntary? Why/ why not?

There are two muscular layers helping the exit of stool. Inner internal anal sphincter works as involuntary and other external anal sphincter works as voluntary control. These muscular structures help in opening and closing of the aperture of the canal which are called as anal sphincter.

Did we have a sphincter in any other part of the digestive cannal? Where was it?

Suppose a person has consumed more fluids than what the body actually need. How do think the extra fluid will be removed from the body?

We have so far seen how several systems work together to bring about the process of digestion. Where does this process draw energy from to run smoothly?