Problem 11 - Biology Concepts and Applications

Question

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

Step-by-Step Solution

Answer

The correct answer is: c. microvilli

Step 1: Understanding the Terms

Let's start by understanding the terms: - **Villi** are small, finger-like projections that extend into the lumen of the small intestine to increase surface area for absorption. - **Microvilli** are even smaller projections found on the villi to further increase surface area, forming the brush border. - **Cilia** are hair-like structures found on the surface of some eukaryotic cells, primarily involved in movement or sensory functions. - **Flagella** are tail-like structures that enable cell movement.

Step 2: Identifying Brush Border Cells

Brush border cells are specialized epithelial cells lining the small intestine. Each cell has a dense covering of microvilli on its apical surface, which appears under the microscope as a 'brush border'. These microvilli increase the cell's surface area and efficiency in nutrient absorption.

Step 3: Determining the Correct Answer

Based on our understanding, the filaments that increase the surface area on brush border cells in the small intestine are the microvilli. These structures form a 'brush border' by projecting from the epithelial cells and significantly enhance the absorptive capacity of the intestine.

Key Concepts

Microvilli

Microvilli are extremely small, hair-like projections that originate from the surface of epithelial cells. You can find them abundantly in the small intestine. Microvilli serve a very special purpose: they increase the surface area of each cell significantly. This expanded surface area plays a crucial role in improving the absorption of nutrients from the food we eat.

Consider microvilli as tiny, efficient, and numerous workers in the intestines that you don't even see. By having these projections, our intestines can absorb nutrients more quickly and thoroughly. The more microvilli each cell has, the better it can absorb vital substances like amino acids and sugars.

• They help in the digestion process by holding enzymes that break down nutrients further.
• Essential for the final steps of the digestion of carbs and proteins.

In essence, microvilli work hard to ensure that your body gets all the nutrients it needs from a healthy diet.

Brush border

The brush border is an area at the very top of the cells that line the small intestine. When you look under a microscope, it seems almost like the bristles of a brush, hence the name "brush border." What you're actually seeing are thousands of microvilli densely packed together.

This border is vital because it optimizes the intestine's ability to absorb nutrients. The microvilli increase the surface area drastically, making it possible for more nutrients to be absorbed simultaneously.

• It contains enzymes essential for breaking down complex sugars and proteins before absorption.
• Acts as a protective barrier against harmful substances in the gut.

So, the brush border isn't just a structural feature—it is a fundamental component in making sure food is converted into the nutrients your body can use.

Intestinal absorption

Intestinal absorption refers to the process where nutrients from digested food pass through the lining of the small intestine into the bloodstream. This process is crucial for providing the body with the necessary elements to produce energy, grow, and repair tissues.

Several key factors make this process highly efficient in the small intestine:

• Surface Area: Thanks to structures like villi and microvilli, the inner surface of the small intestine is vast, allowing more nutrients to be absorbed.
• Enzymatic Activity: Powerful enzymes are present at the brush border, which facilitate the breakdown of complex molecules like proteins and carbohydrates.

Without proper absorption, our bodies wouldn't be able to utilize the nutrients from the food we consume. Thus, efficient intestinal absorption is fundamental to maintaining health and function. With a well-working system, everything from the smallest cell to the largest organ can operate optimally.