Problem 59 - Objective Biology for NEET

Question

Repeated activation of the muscles can lead to the accumulation of due to anaerobic breakdown of glycogen in there causing fatigue. (a) Ethanol (b) Lactic acid (c) Citric acid (d) Butyric acid

Step-by-Step Solution

Answer

The correct option is (b) Lactic acid.

Step 1: Understanding Muscle Fatigue

Muscle fatigue is caused by the long-term or repeated contraction of muscles. This leads to the accumulation of certain byproducts due to anaerobic (without oxygen) metabolism, which is part of the body's response to intense or prolonged physical activity.

Step 2: Understanding Glycogen Breakdown

Glycogen is a form of energy storage in animals, including humans. It is broken down in the muscles during exercise to provide energy. This process, known as glycogenolysis, becomes anaerobic during intense physical activity, meaning it occurs without oxygen.

Step 3: Identifying the Byproduct

The byproduct of anaerobic metabolism or glycogen breakdown in the muscles is lactic acid. When glycogen is broken down anaerobically, it produces lactic acid, which can accumulate in the muscles, contributing to muscle fatigue.

Key Concepts

Anaerobic Metabolism

Anaerobic metabolism is a fascinating process that occurs when your body demands energy faster than your oxygen intake can supply. This typically happens during short bursts of intense exercise like sprinting or heavy lifting. In these situations, your muscles need quick energy, but the oxygen supply might not be able to keep up.
This is where anaerobic metabolism kicks in. This process allows the cells to generate energy without the immediate need for oxygen, tapping into stored forms of energy for a fast response.

• Key for short, intense physical activities.
• Occurs in the cytoplasm of cells — where fast action is crucial.
• Enables rapid energy production albeit less efficient than aerobic pathways.

The result is a quick but temporary boost, helping to sustain the activity until the body can catch up with oxygen delivery.

Glycogen Breakdown

Glycogen breakdown, scientifically termed glycogenolysis, is the body's way of tapping into reserved energy during physical exertion. Glycogen is essentially clusters of glucose stored in the liver and muscles.
When you exercise, especially at high intensity, your body breaks down glycogen into glucose to fuel your muscles. Initially, this breakdown occurs aerobically (with oxygen), but as exertion increases, it shifts to anaerobic conditions.

• Provides a quick source of energy by releasing glucose.
• Essential during activities where immediate energy is needed.
• Switches from aerobic to anaerobic processes as activity intensity rises.

This anaerobic pathway is crucial because it ensures energy is available in situations where oxygen is scarce, although it generates byproducts that can lead to fatigue.

Lactic Acid Accumulation

Lactic acid accumulation is a result of the anaerobic metabolism process during intense exercise. When the body breaks down glycogen without enough oxygen, lactic acid is produced as a byproduct.
Initially, lactic acid can be beneficial as it allows energy production to continue. However, its accumulation in the muscles leads to a burning sensation often associated with fatigue. This is because high levels of lactic acid can decrease the pH within muscles, impairing the muscles' ability to contract effectively.

• Acts as a temporary energy bridge under low oxygen conditions.
• Leads to a burning sensation due to increased acidity in muscles.
• Can be cleared out by the body but may slow down performance and recovery.

Despite its reputation, lactic acid is a natural and necessary part of intense exercise, highlighting the body's remarkable adaptability during high-demand situations.