Final answer:
The small intestine's surface area is vastly increased by the presence of villi and microvilli, measuring roughly 200 square meters. It's roughly 600 times greater than if the intestine were a flat tube, ranging from the size of a tennis court to that of a football field.
Step-by-step explanation:
The surface area of the small intestine is greatly expanded due to structures called villi and microvilli. The inner lining of the small intestine contains these finger-like projections that greatly increase the area available for nutrient absorption. The small intestine itself is nearly 7 meters long in an adult, with a surface area that is 600 times greater than it would be if it were a simple, flat tube. This exceptionally large surface area, which ranges from the size of a tennis court to that of a football field, is essential for efficient digestion and absorption of nutrients.
The villi on the small intestine are tiny, with each one being about 1 millimeter long. Each square inch of the mucosal surface has around 20,000 villi, and each villus is covered in even smaller microvilli. There are more than 100 billion microvilli per square inch of intestinal mucosa. When comparing the entire absorptive surface area of the small intestine to an accessible analogy, it measures approximately 5 meters by 38 meters, which is just a little less than 200 square meters, or about 100 times the surface area of your skin.