Microvilli

Definition

Microvilli are microscopic, finger-like projections that extend from the apical surface of epithelial cells, particularly those lining the small intestine. These structures significantly increase the surface area of the intestinal lining, enhancing the absorption of nutrients from the digested food.

5 Must Know Facts For Your Next Test

1. Microvilli increase the surface area of the small intestine by up to 600-fold, greatly enhancing the absorption of nutrients.
2. Each intestinal epithelial cell can have up to 3,000 microvilli, which are approximately 1 micrometer in length and 0.1 micrometer in diameter.
3. Microvilli contain a core of actin filaments that provide structural support and allow for dynamic changes in their shape and arrangement.
4. The brush border formed by the dense array of microvilli on the intestinal epithelial cells is the site of many digestive enzymes, facilitating the final stages of nutrient breakdown.
5. Disruption or damage to the microvilli can lead to malabsorption disorders, such as celiac disease and tropical sprue, where the body is unable to properly absorb nutrients.

Review Questions

• Explain the role of microvilli in the small intestine and their significance for nutrient absorption.
  • Microvilli are microscopic, finger-like projections that line the apical surface of the epithelial cells in the small intestine. These structures significantly increase the surface area of the intestinal lining, up to 600-fold, which is crucial for the efficient absorption of nutrients from the digested food. The dense array of microvilli, known as the brush border, also serves as the site for many digestive enzymes, facilitating the final stages of nutrient breakdown. By providing a vast surface area for absorption and enzymatic activity, microvilli play a vital role in the body's ability to effectively extract and utilize the essential nutrients from the diet.
• Describe the structural features of microvilli and how they contribute to their function.
  • Microvilli are approximately 1 micrometer in length and 0.1 micrometer in diameter, and each intestinal epithelial cell can have up to 3,000 of these microscopic projections. The core of each microvillus contains a bundle of actin filaments, which provide structural support and allow for dynamic changes in the shape and arrangement of the microvilli. This structural design, along with the dense packing of microvilli on the intestinal epithelial cells, creates the brush border that significantly increases the surface area available for nutrient absorption. The unique morphology and organization of microvilli are essential for maximizing the efficiency of nutrient uptake in the small intestine.
• Analyze the potential consequences of disruption or damage to the microvilli in the small intestine.
  • Disruption or damage to the microvilli can lead to serious malabsorption disorders, such as celiac disease and tropical sprue. When the microvilli are compromised, the body's ability to properly absorb nutrients from the diet is impaired. This can result in various nutritional deficiencies, weight loss, diarrhea, and other gastrointestinal symptoms. The reduced surface area for absorption caused by microvillus damage or dysfunction can have far-reaching consequences, as the body is unable to effectively extract and utilize the essential vitamins, minerals, and macronutrients needed for proper growth, development, and overall health. Understanding the critical role of microvilli in nutrient absorption is key to recognizing and managing conditions that disrupt this vital function of the small intestine.

Related terms

Intestinal Villi: Intestinal villi are small, finger-like projections that line the inner surface of the small intestine, further increasing the surface area for nutrient absorption.

Brush Border: The brush border is the dense array of microvilli present on the apical surface of the intestinal epithelial cells, which creates a brush-like appearance.

Absorption:

Absorption is the process by which nutrients, water, and other substances are taken up from the digestive tract into the bloodstream or lymphatic system for distribution throughout the body.