In the digestive system, which organ is primarily responsible for absorbing nutrients from food?
a) Stomach
b) Small intestine
c) Liver
d) Large intestine
The correct answer and explanation is:
The correct answer is b) Small intestine.
The small intestine is the primary organ responsible for absorbing nutrients from food. It is a long, coiled tube that connects the stomach to the large intestine. The small intestine is divided into three sections: the duodenum, jejunum, and ileum. Each of these parts plays a crucial role in digestion and absorption.
The process of digestion begins in the stomach, where food is broken down into smaller pieces and mixed with gastric juices. However, the absorption of nutrients occurs mainly in the small intestine. After the partially digested food moves from the stomach into the small intestine, it encounters bile from the liver and digestive enzymes from the pancreas. These substances help break down the food into smaller molecules, such as amino acids, fatty acids, and sugars.
The inner lining of the small intestine is covered with tiny finger-like projections called villi, which greatly increase its surface area. Each villus contains even smaller structures called microvilli, forming what is known as the “brush border.” These structures are essential for the absorption of nutrients into the bloodstream. The absorbed nutrients are then transported to various parts of the body through the circulatory system.
While the stomach, liver, and large intestine have important functions in the digestive process, they do not primarily absorb nutrients. The liver processes nutrients and detoxifies harmful substances, and the large intestine absorbs water and electrolytes, but it is the small intestine that does the majority of nutrient absorption. This makes the small intestine the key organ in the digestive system for nutrient uptake.