Why Our Muscles Get Tired Quizizz

The only reason our Muscles get fatigued (tired) is because of the build up of lactic acid.

• True

• False

Answer explanation

Not the ONLY reason. One of the reasons but not nearly as significant as the loss of ions and ATP.

The signals that travel from the brain to the muscles to tell them when to contract (tighten up) happen in a fraction of a second.

• True

• False

The signals that travel from the brain to the muscles are called motor _____________________.

• electrons

• protons

• neurons

• peptides

The energy used to power the contraction of a muscle comes from a molecule called _______________

• ATP

• sodium

• phosphorous

• dextrose

Every time a muscle contracts, energy in the form of ATP gets used up.

• True

• False

As muscles get more tired through repeated contractions, waste products like ______________________ are generated (produced).

• carbon dioxide

• uric acid

• creatine

• lactic acid

Once muscle cells use up ATP as they contract repeatedly, they cannot make any more.

• True

• False

Answer explanation

Yes, they can make up more. That's why you can use the muscle again after some rest. Because your ATP energy has been restored.

Over the course of repeated muscle contractions, there may not be sufficient concentrations of potassium, sodium or calcium ions immediately available near the muscle cell membrane to reset the system properly.

• True

• False

A muscle will ALWAYS be able to generate the action potential necessary to contract a muscle just as long as the brain sends the signal to the muscle to contract.

• True

• False

Answer explanation

Nope, not true. Once the muscle is to the point of exhaustion, even if the brain sends the signal, it will not be able to contact until after you rest it for a minute or two.

Even when ions like sodium, potassium or calcium are depleted in or around the muscle cell, these ions are plentiful elsewhere in the body. And with a little time, they will flow back to the areas where they're needed.

• True

• False