Microvilli

Definition

Microvilli are tiny, finger-like projections found on the surface of epithelial cells, particularly in the small intestine. They serve to significantly increase the surface area of the cell membrane, enhancing the absorption of nutrients and other substances. Their presence is crucial in optimizing the digestive process and facilitating efficient nutrient uptake into the bloodstream.

5 Must Know Facts For Your Next Test

1. Microvilli increase the absorptive capacity of the intestinal lining by providing a larger surface area for nutrient uptake.
2. Each microvillus contains actin filaments that help maintain its structure and provide support to the cell membrane.
3. Microvilli are covered with a glycocalyx, a fuzzy coating made up of glycoproteins and other molecules that play a role in digestion and protection.
4. The presence of microvilli is essential for optimal digestion as they facilitate quicker nutrient absorption into the bloodstream.
5. Microvilli can also be found in other areas of the body, such as the kidneys and some sensory organs, but their most significant function is in the intestines.

Review Questions

• How do microvilli enhance nutrient absorption in the small intestine?
  • Microvilli enhance nutrient absorption by increasing the surface area of epithelial cells in the small intestine. This larger surface area allows for more efficient contact with digested food substances, leading to a greater number of nutrients being absorbed into the bloodstream. The increased area provided by microvilli significantly optimizes the absorption process compared to flat cell membranes.
• What role does the glycocalyx play in relation to microvilli in the intestines?
  • The glycocalyx is a protective layer that coats microvilli and consists of glycoproteins and other molecules. It plays an essential role in digestion by facilitating interactions with digestive enzymes and nutrients. Additionally, it helps protect microvilli from damage and contributes to maintaining optimal conditions for nutrient absorption at the intestinal surface.
• Evaluate how dysfunction or damage to microvilli might impact overall digestive health and nutrient absorption.
  • Dysfunction or damage to microvilli can severely impair digestive health and nutrient absorption. When microvilli are compromised, their ability to increase surface area diminishes, leading to reduced efficiency in absorbing essential nutrients. This can result in malnutrition or deficiencies even when food intake is adequate. Moreover, damaged microvilli may lead to intestinal disorders, causing symptoms like diarrhea, bloating, or abdominal pain due to incomplete digestion and absorption.

Related terms

Villus: A villus is a small, finger-like projection in the lining of the intestines that contains microvilli, increasing the surface area for absorption.

Epithelial Tissue: Epithelial tissue is a type of tissue that lines surfaces and cavities throughout the body, including the gastrointestinal tract, where microvilli are predominantly located.

Brush Border: The brush border refers to the densely packed microvilli on the surface of intestinal epithelial cells, giving it a 'brush-like' appearance and enhancing absorption.