Microvilli

Definition

Microvilli are tiny, finger-like projections found on the surface of epithelial cells, especially in the intestines and kidneys. They increase the surface area of the cell, enhancing its ability to absorb nutrients and other substances. Their presence is crucial in maximizing the efficiency of absorption processes within the gastrointestinal tract, as they provide more surface area for interactions with digested food and facilitate nutrient assimilation.

5 Must Know Facts For Your Next Test

1. Microvilli can be found on the apical surface of epithelial cells, particularly in the small intestine where nutrient absorption occurs.
2. The dense array of microvilli on intestinal epithelial cells forms a structure known as the brush border, which is critical for efficient absorption.
3. Each microvillus contains a core of actin filaments, which provide structural support and maintain the shape of the projections.
4. Microvilli increase the surface area of epithelial cells by up to 600 times, significantly enhancing their absorptive capacity.
5. Damage or reduction in microvilli can lead to malabsorption disorders, affecting overall nutrient uptake and health.

Review Questions

• How do microvilli contribute to the efficiency of nutrient absorption in the gastrointestinal tract?
  • Microvilli enhance nutrient absorption by significantly increasing the surface area of epithelial cells lining the gastrointestinal tract. This larger surface area allows for more interactions between nutrients in the intestinal lumen and the absorptive cells. By forming structures like the brush border, microvilli facilitate efficient transport of nutrients into the cells, which is crucial for maintaining adequate nutrition.
• Discuss how microvilli are structurally adapted to their function in absorption within epithelial tissue.
  • Structurally, microvilli are made up of a core of actin filaments that support their shape and stability. This structural adaptation allows them to extend outward from the cell surface effectively. Their densely packed arrangement on epithelial cells creates a large brush border that maximizes contact with nutrients. The presence of various enzymes on microvilli further aids in breaking down substances for better absorption, making them highly specialized for their role in nutrient assimilation.
• Evaluate the impact of damaged microvilli on overall digestive health and nutrient absorption.
  • Damaged microvilli can severely compromise digestive health by reducing the effective surface area available for nutrient absorption. Conditions such as celiac disease or chronic diarrhea can lead to atrophy of microvilli, resulting in malabsorption syndrome where essential nutrients are not adequately absorbed into the bloodstream. This can cause a cascade of health issues such as weight loss, fatigue, and deficiencies in vitamins and minerals, highlighting their critical role in maintaining digestive efficiency and overall well-being.

Related terms

Villi: Villi are larger, finger-like projections that line the intestinal wall, which also increase surface area for absorption and contain microvilli on their surface.

Epithelial Tissue: A type of tissue that covers body surfaces and lines cavities and organs; it is characterized by closely packed cells and plays a vital role in absorption, secretion, and sensation.

Absorption: The process by which nutrients from digested food are taken up by the cells of the intestinal lining and transferred into the bloodstream.