Problem 130 - Objective Biology for NEET

Question

Which of the following statement is wrong about Chylomicrons? A. Chylomicrons are produced in the epithelial cells of small intestine. B. It contain triglycerides, cholesterol and phospholipids. C. It is protein coated small vesicles. D. Chylomicrons released from the epithelial cell into lacteals. (a) \(\mathrm{A}\) and \(\mathrm{D}\) only (b) \(\mathrm{B}\) and \(\mathrm{C}\) only (c) All of these (d) None of these

Step-by-Step Solution

Answer

The correct answer is (d) None of these. All statements related to Chylomicrons presented here are correct.

Step 1: Checking statement A

Statement A is that 'Chylomicrons are produced in the epithelial cells of small intestine'. This statement is accurate. Chylomicrons are indeed produced in the intestinal epithelial cells. So, it can't be included in the answer.

Step 2: Checking statement B

Statement B is that 'It contains triglycerides, cholesterol and phospholipids'. This is also correct. Chylomicrons are lipoprotein particles that consist of triglycerides (85-92%), phospholipids (6-12%), cholesterol (1-3%) and proteins. So, it can't be included in the answer.

Step 3: Checking statement C

Statement C is 'It is protein coated small vesicles'. This is also a correct statement. Chylomicrons are indeed small vesicles encapsulated by proteins known as apolipoproteins. So, it can't be included in the answer.

Step 4: Checking statement D

Statement D is 'Chylomicrons released from the epithelial cell into lacteals'. This, too, is a correct statement. After their formation, chylomicrons are indeed released from intestinal epithelial cells into the lacteals, which are a part of the lymphatic system. So, it can't be included in the answer.

Key Concepts

Intestinal Epithelial Cells

Intestinal epithelial cells play an essential role in our digestive process and the absorption of nutrients. These cells line the inner surface of the small intestine, creating a barrier between the digestive contents and the body's internal environment.
They are specially adapted to facilitate the efficient uptake of nutrients.

• These cells possess microvilli, which are tiny projections that increase the surface area for absorption.
• The increased surface area maximizes contact with digested food particles, enhancing nutrient absorption.

The production of chylomicrons is one of their key functions. These cells absorb digested fats, which are then reassembled into triglycerides.
The triglycerides, along with cholesterol and phospholipids, are packaged into chylomicrons.
This packaging process involves coating the lipid particles with proteins, forming what we call lipoproteins.

Lipoprotein Particles

Lipoprotein particles are specifically structured to transport lipids, which are fats, through the bloodstream. They are critical in lipid metabolism and maintaining cellular health.
Chylomicrons are a type of lipoprotein particle designed to transport dietary lipids from the small intestine to other locations in the body.

• They primarily contain triglycerides, which make up 85-92% of their structure, alongside components like phospholipids, cholesterol, and proteins.
• The protein coating, known as apolipoproteins, stabilizes the chylomicrons in the aqueous environment of the lymph and blood.

Chylomicrons facilitate the delivery of absorbed dietary fats to muscle tissue and adipose (fat) tissue, where they can be used for energy storage or metabolism.
By acting as lipid carriers, lipoprotein particles like chylomicrons are vital for ensuring that our cells receive the necessary nutrients to function.

Lymphatic System

The lymphatic system is a crucial component of the circulatory and immune systems. It primarily functions to transport lymph, a fluid containing white blood cells, throughout the body.
An essential aspect of the lymphatic system is its role in the transportation of chylomicrons, linking it directly to digestion and nutrient absorption.

• Lacteals are small lymphatic vessels located within the villi of the small intestine.
• They are responsible for absorbing chylomicrons from intestinal epithelial cells.

Once inside the lacteals, chylomicrons enter the lymphatic circulation, bypassing the liver initially and directly entering the bloodstream through the thoracic duct.
This efficient transport method allows chylomicrons to deliver dietary fats swiftly to various body tissues, highlighting the lymphatic system's integral role in lipid metabolism.