Problem 11 - Biology: The Unity and Diversity of Life

Question

Tiny filaments called _____ increase the surface area of a brush border cell. a. villi b. microvilli c. cilia d. flagella

Step-by-Step Solution

Answer

The tiny filaments are called microvilli.

Step 1: Understand the Structure

Brush border cells are specialized cells, often found in the small intestine, where they play a crucial role in digestion and absorption. These cells have structures that increase their surface area.

Step 2: Examine the Options

Review the provided options: a. villi, b. microvilli, c. cilia, and d. flagella. Each of these is a type of small structure found on cells that can increase surface area or have other functions.

Step 3: Identify the Correct Structure

Brush border cells specifically have 'microvilli' covering their surface. These are tiny hair-like projections that significantly increase the cell's surface area to aid in nutrient absorption.

Key Concepts

Brush Border Cells

Brush border cells are specialized epithelial cells lining the lumen of the intestines. These cells are a crucial component of the digestive system. They have tiny projections on their surface called microvilli, often forming a dense layer resembling a brush, which is why they're named 'brush border cells.' The main function of these cells is to aid in the absorption of nutrients from the digestive tract into the body.
The brush-like appearance of these cells results from the dense array of microvilli. This structure plays a vital role in digestion and enhances the cell surface area for more efficient interaction with digested food.
This increased surface area allows brush border cells to maximize nutrient uptake and ensures our bodies get the essential vitamins, minerals, and other compounds needed to maintain overall health.

Small Intestine

The small intestine is a long, winding tube that forms a significant part of the gastrointestinal tract. It serves several purposes but is primarily involved in the digestion and absorption of nutrients.
After food is partially broken down in the stomach, it passes into the small intestine, where it undergoes further digestion by enzymes. The small intestine is divided into three parts:

• Duodenum
• Jejunum
• Ileum

Each section has a unique role in the digestive process. The duodenum primarily continues the digestion process, while the jejunum and ileum are mostly involved in nutrient absorption. The inner walls of the small intestine are lined with many folds and projections, such as villi and microvilli, to increase the surface area for greater absorption efficiency. It's this incredible construction that allows the small intestine to efficiently absorb the nutrients our bodies need.
This complex structure ensures that our bodies retrieve essential nutrients from the food we consume, facilitating processes essential for life.

Nutrient Absorption

Nutrient absorption is a vital process that occurs extensively in the small intestine. Once the stomach has broken down proteins, fats, and carbohydrates into simpler molecules, these nutrients are ready to be absorbed by the body.
The small intestine is equipped with specialized cells designed for this job, primarily brush border cells, which have microvilli to maximize surface area. This structure significantly enhances the ability of nutrient molecules to pass through the intestinal wall and into the bloodstream.
Several nutrients absorbed include:

• Carbohydrates (as glucose and other simple sugars)
• Proteins (as amino acids)
• Fats (as fatty acids and glycerol)
• Vitamins and minerals

The efficiency of nutrient absorption is crucial because it ensures that our bodies have the necessary fuel for energy, growth, and repair. Any failure or reduction in the absorption capability can lead to nutritional deficiencies, affecting health and wellness. Therefore, understanding the structures and processes involved helps in appreciating how our bodies sustain themselves and the importance of a healthy diet.