Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 16: Problem 4

Rigor is a muscle condition in which muscle fibers, depleted of ATP and phosphocreatine, develop a state of extreme rigidity and cannot be easily extended. (In death, this state is called rigor mortis, the rigor of death.) From what you have learned about muscle contraction, explain the state of rigor in molecular terms.

Short Answer

Expert verified
Rigor, or muscle rigidity, occurs when muscle fibers are depleted of ATP and phosphocreatine. This results in the myosin heads being unable to detach from the actin filaments due to a lack of energy, causing extreme rigidity in the muscle fibers.

Step by step solution

01

Understanding muscle contraction

Muscle contraction happens as a result of a process called the sliding filament theory. This involves thick and thin filaments within the muscle fiber sliding past each other, creating a contraction. It requires energy, which is provided by ATP.
02

Role of ATP in muscle contraction

ATP provides the energy for muscle contraction by detaching the myosin heads from the actin filaments, which allows the relaxation of the muscle. When ATP binds to myosin, it breaks down into ADP and an inorganic phosphate, which releases the energy required for the myosin head to change its shape and bind to actin, leading to muscle contraction.
03

Role of Phosphocreatine

Phosphocreatine acts as a reserve for high energy phosphates. In conditions when ATP reserves are depleted, phosphocreatine donates a phosphate group to ADP to generate ATP to continue the muscle contraction process.
04

Explanation of Rigor

Rigor occurs when there is a depletion of ATP and phosphocreatine in muscle fibers. This means that the myosin heads are unable to detach from the actin filaments as they do not have the energy that is normally provided by ATP. As a result, the muscle fibers become rigid and cannot be easily extended.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

When athletes overexert themselves on hot days, they often suffer immobility from painful muscle cramps. Which of the following is a reasonable hypothesis to explain such cramps? a. Muscle cells do not have enough ATP for normal muscle relaxation. b. Excessive sweating has affected the salt balance within the muscles. c. Prolonged contractions have temporarily interrupted blood flow to parts of the muscle. d. All of the above.

Use the equations of Chapter 9 to determine the free energy difference represented by a \(\mathrm{Ca}^{2+}\) gradient across the sarcoplasmic reticulum membrane if the luminal (inside) concentration of \(\mathrm{Ca}^{2+}\) is \(1 \mathrm{m} M\) and the concentration of \(\mathrm{Ca}^{2+}\) in the solution bathing the muscle fibers is \(1 \mu M\).

When an action potential (nerve impulse) arrives at a muscle membrane (sarcolemma), in what order do the following events occur? a. Release of \(\mathrm{Ca}^{2+}\) ions from the sarcoplasmic reticulum b. Hydrolysis of ATP, with release of energy c. Detachment of myosin from actin d. Sliding of myosin along actin filament e. Opening of switch 1 and switch 2 on myosin head

An ATP analog, \(\beta, \gamma\) -methylene-ATP, in which a \(-\mathrm{CH}_{2}-\) group replaces the oxygen atom between the \(\beta\) - and \(\gamma\) -phosphorus atoms, is a potent inhibitor of muscle contraction. At which step in the contraction cycle would you expect \(\beta, \gamma\) -methylene-ATP to block contraction?

ATP stores in muscle are augmented or supplemented by stores of phosphocreatine. During periods of contraction, phosphocreatine is hydrolyzed to drive the synthesis of needed ATP in the creatine kinase reaction: Phosphocreatine \(+\mathrm{ADP} \longrightarrow\) creatine \(+\mathrm{ATP}\) Muscle cells contain two different isozymes of creatine kinase, one in the mitochondria and one in the sarcoplasm. Explain.
See all solutions

Recommended explanations on Chemistry Textbooks

Ionic and Molecular Compounds

Read Explanation

Chemical Analysis

Read Explanation

The Earths Atmosphere

Read Explanation

Kinetics

Read Explanation

Physical Chemistry

Read Explanation

Inorganic Chemistry

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free