Wednesday, Oct. 8 - The Human Body - The Digestive System

Everything that goes in your mouth is processed by the digestive system. There are three main processes:

• Digestion – breakdown of food into nutrients
• Absorption – movement of nutrients throughout the body
• Elimination – removal of undigested material

Digestion starts when you put food in your mouth – chewing and saliva start breaking down food. The food goes down your esophagus into the stomach, where the digestive juices break it down more.

The partially digested food moves from the stomach to the small intestine, where there is some absorption. Nutrients and water pass through the walls of the small intestine to the bloodstream. Waste moves into the large intestine for elimination.

The liver, gallbladder and pancreas aid digestion even though food does not mass through them. The liver is the largest internal organ and it has many functions. In digestion, it makes bile, which breaks down fat. Excess bile is stored in the gallbladder and it releases the bile into the small intestine as needed. The pancreas produces digestive enzymes that help break down proteins, carbohydrates and fats.

The Excretory System

Your body has to get rid of waste – that’s where the excretory system comes in.

Your skin is one of the organs of the excretory system. You sweat – it helps your body cool down, but it also helps your body get rid of excess water and salt.

The lungs are also part of the excretory system (even though they are part of the circulatory system). They get rid of carbon dioxide, which is a waste product from cell processes.

Urine is produced by the kidneys. You have two kidneys which use millions of tiny filters to separate waste products out. The waste (urine) passes through the ureter and is stored in the bladder – when it is full, you pee.

Solid waste is prepared in the large intestine, which removes water from the waste. Then it comes out as feces.