contraction

Physics

(noun)

A reversible reduction in size.

Related Terms

  • atrium
  • ventricle
Economics

(noun)

A period of economic decline or negative growth.

Related Terms

  • expansion
  • peak
  • trough

Examples of contraction in the following topics:

  • Types of Muscle Contractions: Isotonic and Isometric

    • Muscle contractions are defined by the changes in the length of the muscle during contraction.
    • Several types of muscle contractions occur and they are defined by the changes in the length of the muscle during contraction.
    • A concentric contraction is a type of muscle contraction in which the muscles shorten while generating force, overcoming resistance.
    • A yielding contraction occurs when a muscle contraction is opposed by resistance.
    • An overcoming contraction occurs when a muscle contraction is opposed by an immovable object.
  • ATP and Muscle Contraction

    • ATP is critical for muscle contractions because it breaks the myosin-actin cross-bridge, freeing the myosin for the next contraction.
    • Muscles contract in a repeated pattern of binding and releasing between the two thin and thick strands of the sarcomere.
    • When the actin is pulled approximately 10 nm toward the M-line, the sarcomere shortens and the muscle contracts.
    • Therefore, without ATP, muscles would remain in their contracted state, rather than their relaxed state.
    • With each contraction cycle, actin moves relative to myosin.
  • Futures and Forward Contracts

    • Standardized contracts allow investors to buy and sell futures contracts on organized exchanges.
    • You could sell your futures contract on the derivatives market if you no longer want the contract.
    • Contract size is 10,000 barrels of petroleum with a contract price of $75 per barrel.
    • On the other side of the contract, the bank benefits from this contract.
    • If a speculator bought this contract from the Malaysian bank, then he or she loses approximately $250,000 on this contract if the contract matured today.
  • Interactions of Skeletal Muscles

    • Skeletal muscle contractions can be grouped based on the length and frequency of contraction.
    • The time between the stimulus and the initiation of contraction is termed the latent period, which is followed by the contraction period.
    • At peak contraction the muscle relaxes and returns to its resting position.
    • After contraction the muscle relaxes back to a resting level of tension.
    • If the frequency of these contractions increases to the point where maximum tension is generated and no relaxation is observed then the contraction is termed a tetanus.
  • Contract Manufacturing

    • In contract manufacturing, a hiring firm makes an agreement with the contract manufacturer to produce and ship the hiring firm's goods.
    • A contract manufacturer ("CM") is a manufacturer that enters into a contract with a firm to produce components or products for that firm .
    • In a contract manufacturing business model, the hiring firm approaches the contract manufacturer with a design or formula.
    • Mutual Benefit to Contract Site: A contract between the manufacturer and the company it is producing for may last several years.
    • Compare the benefits and risks of employing a contract manufacturer (CM)
  • Review Your RFI, RFP and Contract Language

  • Velocity and Duration of Muscle Contraction

    • Skeletal muscle contractions can be broadly separated into twitch and tetanic contractions.
    • In a twitch contraction, a short burst of stimulation causes the muscle to contract, but the duration is so short that the muscle begins relaxing before reaching peak force.
    • If the stimulation is long enough, the muscle reaches peak force and plateaus at this level, resulting in a tetanic contraction.
    • Twitch contractions are short in duration and though they have high velocity, they begin resting before reaching peak force.
    • Tetanic contractions, which are long in duration, reach peak force and plateau.
  • Mechanism and Contraction Events of Cardiac Muscle Fibers

    • The gap junctions spread action potentials to support the synchronized contraction of the myocardium.
    • In cardiac, skeletal, and some smooth muscle tissue, contraction occurs through a phenomenon known as excitation contraction coupling (ECC).
    • The actual mechanical contraction response in cardiac muscle occurs via the sliding filament model of contraction.
    • The pathway of contraction can be described in five steps:
    • This removal of the troponin complex frees the actin to be bound by myosin and initiates contraction.
  • Abnormal Contractions of Skeletal Muscle

    • Involuntary muscle contractions are referred to as spasms, and can be due to abnormal activity of the nerve or the muscle.
    • In medicine, a spasm is a sudden, involuntary contraction of a muscle, a group of muscles, or a hollow organ, or a similarly sudden contraction of an orifice .
    • There are a variety of other causes of involuntary muscle contractions, which may be more serious, depending on the cause.
    • Examples of spasms include muscle contractions due to abnormal nerve stimulation, or abnormal activity of the muscle itself.
    • Spasmodic muscle contraction may be due to a large number of medical conditions, including the dystonias.
  • Excitation–Contraction Coupling

    • Excitation–contraction coupling is the connection between the electrical action potential and the mechanical muscle contraction.
    • Excitation–contraction coupling is the physiological process of converting an electrical stimulus to a mechanical response.
    • It is the link (transduction) between the action potential generated in the sarcolemma and the start of a muscle contraction .
    • This diagram shows excitation-contraction coupling in a skeletal muscle contraction.
    • Explain the process of excitation-contraction coupling and the role of neurotransmitters
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