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Related Concept Videos

Relaxation of Skeletal Muscles01:29

Relaxation of Skeletal Muscles

The period of muscle contraction primarily influences the duration of stimulation at the neuromuscular junction (NMJ), the presence of free calcium ions in the sarcoplasm, and the availability of energy or ATP to support contractions.
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
Microscopic Anatomy of Skeletal Muscles01:13

Microscopic Anatomy of Skeletal Muscles

Skeletal muscle cells, also called muscle fibers, are distinctly elongated, multi-nucleated, slender biological units. They are packed with specialized structures designed to facilitate their primary function, which is contraction.
The muscle sarcolemma is a plasma membrane enclosing each muscle cell that conducts electrical signals called action potentials. The sarcolemma extends into the cell to form T-tubules, ensuring the neural impulses are uniformly distributed across the entire muscle...
Motor Unit Stimulation01:20

Motor Unit Stimulation

When the neuron of a motor unit fires an action potential, it triggers a series of events, leading to a twitch contraction in the muscle fibers. The process of excitation-contraction coupling is crucial in relaying the action potential to the muscle fibers.
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
Fascicle Arrangement in Skeletal Muscles01:25

Fascicle Arrangement in Skeletal Muscles

Fascicles are bundles of muscle fibers in a skeletal muscle. Muscle fascicle arrangement is directly associated with the power and range of motion of various muscles. The configuration of these fascicles can vary, leading to different functional outcomes.
The four primary types of muscle based on fascicle arrangement are:
Smooth Muscle Contraction01:25

Smooth Muscle Contraction

Smooth muscle contraction is a complex process vital for various bodily functions, from maintaining blood vessel tension to facilitating the movement of food through the digestive tract. Unlike striated muscles, smooth muscle contraction begins more slowly and lasts longer.
The onset of contraction is triggered by an increase in calcium ions within the sarcoplasm, similar to the process in striated muscle. However, smooth muscles have a relatively smaller reservoir of the sarcoplasmic...
Muscle Contraction01:10

Muscle Contraction

In skeletal muscles, acetylcholine is released by nerve terminals at the motor endplate—the point of synaptic communication between motor neurons and muscle fibers. The binding of acetylcholine to its receptors on the sarcolemma allows entry of sodium ions into the cell and triggers an action potential in the muscle cell. Thus, electrical signals from the brain are transmitted to the muscle. Subsequently, the enzyme acetylcholinesterase breaks down acetylcholine to prevent excessive muscle...

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Utilization of Microscale Silicon Cantilevers to Assess Cellular Contractile Function In Vitro
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Contracting the 'mus cells'--does down-sizing suit us for diving into the memory pool?

Sema Kurtulus1, Pulak Tripathi, Joseph T Opferman

  • 1Division of Immunobiology, Department of Pediatrics, University of Cincinnati, Children's Hospital Medical Center, Cincinnati, OH 45229, USA.

Immunological Reviews
|July 20, 2010
PubMed
Summary

T-cell homeostasis is vital for immunity. This review explores how T-cell contraction, regulated by Bcl-2 family members like Bim and Bcl-2, resets immune balance and prevents autoimmunity.

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Area of Science:

  • Immunology
  • Cell Biology

Background:

  • T-cell homeostasis is crucial for immune system function.
  • Naive T cells expand upon antigen exposure, gaining effector functions.
  • Effector T cells undergo apoptosis (contraction) or become memory cells, resetting homeostasis.

Purpose of the Study:

  • To review mechanisms of T-cell contraction.
  • To discuss the role of Bcl-2 family members in T-cell apoptosis.
  • To explore how some T cells evade death and form memory cells.

Main Methods:

  • Review of in vivo and in vitro studies.
  • Analysis of signaling pathways involved in T-cell apoptosis.
  • Focus on Bcl-2 family members, particularly Bim and Bcl-2.

Main Results:

  • Initial studies suggested death receptor signaling in T-cell contraction.
  • Recent in vivo studies highlight Bcl-2 family members as critical regulators.
  • Bim (pro-apoptotic) and Bcl-2 (anti-apoptotic) are essential for T-cell culling.

Conclusions:

  • T-cell contraction is a key process for immune regulation and preventing autoimmunity.
  • Bcl-2 family members, especially Bim and Bcl-2, are essential for this process.
  • Understanding T-cell survival mechanisms is key to T-cell memory formation.