key term - Microvilli

Definition

Microvilli are tiny, finger-like projections that extend from the surface of epithelial cells, particularly in the intestines, and play a crucial role in increasing the surface area for absorption. These structures are composed of actin filaments and are closely packed together, creating a brush border appearance. The increased surface area provided by microvilli enhances the efficiency of nutrient absorption during the digestive process.

5 Must Know Facts For Your Next Test

1. Microvilli significantly increase the absorptive capacity of the intestinal epithelium by providing a larger surface area for interaction with digested nutrients.
2. These structures contain enzymes and transport proteins that facilitate the breakdown and absorption of nutrients such as carbohydrates, proteins, and lipids.
3. Microvilli play a vital role in maintaining gut health by assisting in the absorption of water and electrolytes, which are crucial for homeostasis.
4. The brush border formed by microvilli is not only important for absorption but also helps in creating a barrier against pathogens and toxins.
5. Damage to microvilli can lead to malabsorption syndromes, resulting in nutrient deficiencies and gastrointestinal disorders.

Review Questions

• How do microvilli enhance nutrient absorption in the gastrointestinal tract?
  • Microvilli enhance nutrient absorption by dramatically increasing the surface area of the intestinal epithelial cells. This larger surface area allows for more efficient contact between nutrients and the cell membranes, facilitating greater absorption rates. Additionally, microvilli contain enzymes that help break down complex nutrients into simpler forms that can be absorbed more easily.
• Discuss the structural differences between microvilli and villi, and their respective roles in digestion.
  • Microvilli are much smaller than villi; they are microscopic projections on individual epithelial cells, while villi are larger finger-like projections that extend into the lumen of the intestine. Both structures serve to increase surface area for absorption; however, villi are responsible for moving nutrients toward the capillaries, while microvilli further enhance this process by providing enzymatic functions and transport mechanisms on their surfaces. Together, they create a highly efficient system for nutrient uptake.
• Evaluate how damage to microvilli can impact overall health and nutritional status.
  • Damage to microvilli can lead to impaired nutrient absorption, resulting in malabsorption syndromes such as celiac disease or irritable bowel syndrome. This impairment can cause deficiencies in essential vitamins and minerals, leading to symptoms like fatigue, weight loss, and digestive issues. Over time, malnutrition can affect overall health, compromising immune function and increasing vulnerability to infections. Thus, maintaining healthy microvilli is crucial for ensuring adequate nutrition and overall well-being.

Related terms

Villi: Villi are small, finger-like projections found on the inner surface of the small intestine that increase the surface area for absorption, similar to microvilli but larger in size.

Epithelial Cells: Epithelial cells are specialized cells that line various surfaces and cavities in the body, including the gastrointestinal tract, and are involved in absorption, secretion, and protection.

Intestinal Brush Border: The intestinal brush border refers to the collective structure formed by microvilli on the surface of intestinal epithelial cells, which is essential for maximizing nutrient absorption.