Problem 10 - Biology: Science for Life with Physiology

Question

Lo9 The immune system can recognize a virus you have been exposed to once because A. you harbor the virus for many years; B. we have genes to combat every type of virus; \(\mathrm{C}\). a cell that makes receptors to a virus multiplies on exposure to it and produces memory cells; D. a copy of the viral genome is inserted into a memory cell.

Step-by-Step Solution

Answer

Option C is correct: memory cell formation allows recognition of past viruses.

Step 1: Understand the Question

The question is asking why the immune system can recognize a virus you have been exposed to before. There are four options provided that could explain this phenomenon.

Step 2: Analyze the Options

We need to evaluate each option to determine which one accurately describes how the immune system remembers a virus.

Step 3: Evaluate Option A

Option A suggests that the body continues to harbor the virus for many years, which is generally incorrect as most viruses are cleared by the immune system after the infection is resolved.

Step 4: Evaluate Option B

Option B claims that we have genes to combat every type of virus. This is partially true in that our immune system has the capacity to fight many viruses, but it does not directly account for memory and recognition of specific past viruses.

Step 5: Evaluate Option C

Option C states that cells making receptors to a virus multiply upon exposure to it and produce memory cells. This is accurate as it describes the role of B and T lymphocytes in the adaptive immune response, which create memory cells that allow for faster responses upon re-exposure to the virus.

Step 6: Evaluate Option D

Option D suggests that a copy of the viral genome is inserted into a memory cell, which is not the mechanism by which the immune system recognizes viruses. Memory cells store information about the virus but do not integrate the viral genome.

Step 7: Determine the Correct Answer

Based on the evaluation of each option, Option C is the correct answer. It accurately describes the process of immunity through the proliferation of cells creating specific receptors and forming memory cells for quick response upon re-exposure.

Key Concepts

Virus Recognition

Virus recognition is a crucial function of the immune system. The process involves identifying and responding to foreign invaders, such as viruses, that enter the body. When a virus invades, it presents itself with unique molecules on its surface called antigens. The immune system detects these antigens using specialized receptors.

• These receptors are found on the surface of immune cells like B and T lymphocytes.
• The receptors must match the virus's antigens precisely to recognize and initiate an appropriate response.

Recognition is the first step in mounting an effective immune response, triggering further actions by the immune system to neutralize the threat.

Memory Cells

Memory cells are central to the immune system's ability to recall past encounters with pathogens, such as viruses. They are a type of lymphocyte, which are white blood cells primarily found in the lymphatic system.
When the body first encounters a virus, it triggers the production of specific B and T cells that can fight the virus. Among these are a subset of cells that become memory cells after the virus has been cleared from the body.

• Memory cells "remember" the specific antigens associated with the virus.
• During a second encounter with the same virus, memory cells enable a rapid and potent immune response.

This process ensures that subsequent infections are less severe or even asymptomatic, as the immune system quickly recognizes and neutralizes the virus.

Adaptive Immune Response

The adaptive immune response is a highly specific defense mechanism that the body employs against pathogens like viruses. It differs from the innate immune response, which provides a general defense against infection.
One key feature of the adaptive immune response is its ability to adapt and remember specific pathogens for future encounters. This is achieved through several mechanisms:

• Upon first exposure, the immune system creates specific B and T cells that recognize the virus.
• These cells not only fight the current infection but also form memory cells for long-term immunity.
• On subsequent exposures, the presence of memory cells allows for a faster and more effective immune response.

The adaptive immunity thus plays a crucial role in protecting the body against reinfections and in the effectiveness of vaccines, which rely on creating memory cells without causing the disease.