Problem 89 - Objective Biology for NEET

Question

Cells constituting the wall of capillaries are (a) Parietal (b) Endothelial (c) Oxyntic (d) Haemocytes

Step-by-Step Solution

Answer

The cells constituting the wall of capillaries are Endothelial.

Step 1: Understanding Capillaries

Capillaries are the smallest blood vessels in the body. They connect arterioles and venules and enable the exchange of water, oxygen, carbon dioxide, and other nutrients and waste substances between the blood and the surrounding tissues.

Step 2: Identifying the Cells

The wall of capillaries is made of a single layer of a specific type of cells which is known as endothelial cells. These cells are thin and flat, they form a type of lining in the capillary wall that allows materials to be exchanged between the blood and surrounding tissues easily.

Step 3: Eliminating Incorrect Options

Parietal cells are found in the stomach and secrete gastric acid. Oxyntic cells are essentially the same as parietal cells, they are just another name for them. Haemocytes are immune cells found in invertebrates. None of these are present in the walls of capillaries.

Key Concepts

Endothelial Cells

Endothelial cells are specialized cells that line the inside of blood vessels in your body. They form a single flat layer, creating a barrier between the blood inside the capillaries and the surrounding tissues. This layer is crucial because it controls the movement of substances in and out of the bloodstream.

• Endothelial cells are extremely thin, allowing them to facilitate the seamless exchange of gases, nutrients, and waste products.
• They play a key role in maintaining the proper function of capillaries by ensuring that the exchange of substances occurs efficiently.
• Their unique structure allows for flexibility and the ability to respond to changes in the bloodstream, such as altered flow rates or pressure.

Endothelial cells are not just passive linings but are active participants in many physiological processes. They help regulate blood flow and pressure, respond to inflammatory signals, and manage the growth of new blood vessels.

Blood Vessels

Blood vessels are vital components of the circulatory system that transport blood throughout your body. They are essential for maintaining life by supplying tissues with necessary nutrients and oxygen while removing waste products. Blood vessels come in different forms based on their function and structure.

• Arteries carry oxygen-rich blood away from the heart.
• Veins return oxygen-depleted blood back to the heart.
• Capillaries are tiny vessels that connect arteries and veins, facilitating the exchange of molecules between blood and tissue.

The unique structure of blood vessels is designed to withstand different pressure levels within the bloodstream. Arteries, for example, have thicker walls to cope with the high pressure at which blood is pumped by the heart. Veins contain valves that prevent blood from flowing backward, especially in the limbs.

Exchange of Substances

The exchange of substances is a fundamental process that occurs in capillaries. This process enables the delivery of vital nutrients and oxygen to cells while allowing the removal of carbon dioxide and other metabolic waste products.

• Oxygen and Nutrients: Oxygen diffuses from the blood into the tissues, while nutrients like glucose and amino acids are delivered to cells.
• Carbon Dioxide and Waste: Carbon dioxide produced as a waste product of cellular respiration diffuses from the tissues back into the blood for removal.
• Fluid Exchange: Water and solutes move across the endothelial cells, helping to maintain proper fluid balance in the body.

The efficiency of this exchange process is crucial for maintaining cellular health and function. Any disruption in this process can lead to tissue damage and impaired organ function. Additionally, the permeability of the endothelial cells can be adjusted according to the body's needs, making this process dynamic and responsive.