Related Experiment Video

Updated: Aug 16, 2026

Assessment of Calcium Sparks in Intact Skeletal Muscle Fibers
11:22

Assessment of Calcium Sparks in Intact Skeletal Muscle Fibers

Published on: February 24, 2014

Ca2+ sparks in skeletal muscle

Michael G Klein1, Martin F Schneider

  • 1Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.

Progress in Biophysics and Molecular Biology
|August 30, 2005
PubMed

More Related Videos

In Vivo Calcium Imaging in C. elegans Body Wall Muscles08:03

In Vivo Calcium Imaging in C. elegans Body Wall Muscles

Published on: October 20, 2019

Ex Vivo Assessment of Contractility, Fatigability and Alternans in Isolated Skeletal Muscles14:02

Ex Vivo Assessment of Contractility, Fatigability and Alternans in Isolated Skeletal Muscles

Published on: November 1, 2012

Related Concept Videos

Excitation-Contraction Coupling in Skeletal Muscles01:20

Excitation-Contraction Coupling in Skeletal Muscles

Excitation-contraction coupling is a series of events that occur between generating an action potential and initiating a muscle contraction. It occurs at the triad, a structure found in skeletal muscle fibers that comprise a T-tubule and terminal cisternae of the sarcoplasmic reticulum on each side. These triads are visible in longitudinally sectioned muscle fibers. They are typically located at the A-I junction — the junction between the A and I bands of the sarcomere.
When an action potential...
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...
Muscle Contraction01:15

Muscle Contraction

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.
Cross-bridge Cycle01:26

Cross-bridge Cycle

As muscle contracts, the overlap between the thin and thick filaments increases, decreasing the length of the sarcomere—the contractile unit of the muscle—using energy in the form of ATP. At the molecular level, this is a cyclic, multistep process that involves binding and hydrolysis of ATP, and movement of actin by myosin.
Generation of Action Potential in Skeletal Muscles01:24

Generation of Action Potential in Skeletal Muscles

Every cell in the body maintains a membrane potential due to an uneven distribution of positive and negative charges across its plasma membrane. The membrane potential is measured in millivolts and quantifies the difference in charge across the membrane.
Like neurons, muscle cells are also regarded as excitable due to their capacity to change in response to stimuli, primarily due to voltage-gated ion channels embedded in their plasma membranes, which get activated by alterations in the cell's...