Question

Why does weightlifting produce lactic acid buildup in muscle tissue? A. Some highly active muscle tissue uses ATP faster than can be supplied by aerobic respiration. B. Some highly active muscle tissue uses ATP faster than can be supplied by anaerobic respiration. C. Lactic acid is always a byproduct of ATP production. D. The Krebs cycle produces lactic acid.

Short answer

A: Some highly active muscle tissue uses ATP faster than can be supplied by aerobic respiration.

Step-by-step solution

Understand the Context

During weightlifting, muscles exert effort at an intensity that often surpasses the rate at which aerobic respiration can supply ATP. This leads to an increased reliance on anaerobic respiration to meet the energy demands.

Aerobic vs. Anaerobic Respiration

Aerobic respiration uses oxygen to produce ATP efficiently but at a slower rate. Anaerobic respiration, used during high-intensity exercises like weightlifting, does not require oxygen and produces ATP rapidly but less efficiently.

Byproducts of Anaerobic Respiration

During anaerobic respiration, glucose is broken down into ATP and lactic acid. The buildup of lactic acid occurs because it is a byproduct of the rapid ATP production needed when oxygen is scarce.

Eliminate Incorrect Options

Options B, C, and D have inaccuracies: B suggests anaerobic respiration can't supply ATP fast enough, C implies lactic acid is always produced in ATP production, and D incorrectly states the Krebs cycle produces lactic acid. The Krebs cycle operates in aerobic conditions.

Choose the Correct Option

Given the explanation in the previous steps, the correct answer is A: 'Some highly active muscle tissue uses ATP faster than can be supplied by aerobic respiration.' This leads to reliance on anaerobic pathways and subsequent lactic acid buildup.

Key concepts

aerobic respiration

Aerobic respiration is a process that produces energy by using oxygen. This happens in the mitochondria, the powerhouse of the cell. This type of respiration produces ATP (adenosine triphosphate), which is the primary energy carrier in cells.

Aerobic respiration is highly efficient. It can produce up to 38 molecules of ATP from one molecule of glucose. Also, it has a slower pace and is more sustainable for activities like walking or jogging.

However, during intense activities (like weightlifting), your muscles demand more ATP quickly. Aerobic respiration can't keep up with this fast energy requirement. Thus, your body shifts to a different pathway called anaerobic respiration.

anaerobic respiration

Anaerobic respiration is a way of producing energy without using oxygen. It occurs in the cytoplasm of cells and is much quicker than aerobic respiration. This process is crucial during high-intensity activities when your muscles need immediate energy.

In anaerobic respiration, glucose is broken down into ATP and lactic acid. However, it is less efficient, producing only 2 molecules of ATP from each glucose molecule.

The byproduct, lactic acid, builds up in muscle tissues during this process. This buildup causes the burning sensation often felt during intense exercise. Unlike aerobic respiration, anaerobic respiration can only support energy needs for a short duration due to lactic acid accumulation.

energy metabolism

Energy metabolism encompasses all the chemical reactions that are involved in maintaining the living state of cells and the organism. This includes both aerobic and anaerobic respiration.

These processes work together to manage the energy supply based on the body's immediate needs. During rest or low-intensity activities, aerobic respiration is the primary method, supplying sustained energy. During high-intensity exercise, anaerobic respiration takes over to meet rapid energy demands.

Understanding energy metabolism helps in planning effective exercise routines and managing physical exertion without causing undue stress on the body. It explains why muscles sometimes rely on anaerobic pathways and why lactic acid buildup happens during intense activities like weightlifting.