Concept

Sarcoplasmic reticulum

Summary
The sarcoplasmic reticulum (SR) is a membrane-bound structure found within muscle cells that is similar to the smooth endoplasmic reticulum in other cells. The main function of the SR is to store calcium ions (Ca2+). Calcium ion levels are kept relatively constant, with the concentration of calcium ions within a cell being 10,000 times smaller than the concentration of calcium ions outside the cell. This means that small increases in calcium ions within the cell are easily detected and can bring about important cellular changes (the calcium is said to be a second messenger). Calcium is used to make calcium carbonate (found in chalk) and calcium phosphate, two compounds that the body uses to make teeth and bones. This means that too much calcium within the cells can lead to hardening (calcification) of certain intracellular structures, including the mitochondria, leading to cell death. Therefore, it is vital that calcium ion levels are controlled tightly, and can be released into the cell when necessary and then removed from the cell. The sarcoplasmic reticulum is a network of tubules that extend throughout muscle cells, wrapping around (but not in direct contact with) the myofibrils (contractile units of the cell). Cardiac and skeletal muscle cells contain structures called transverse tubules (T-tubules), which are extensions of the cell membrane that travel into the centre of the cell. T-tubules are closely associated with a specific region of the SR, known as the terminal cisternae in skeletal muscle, with a distance of roughly 12 nanometers, separating them. This is the primary site of calcium release. The longitudinal SR are thinner projects, that run between the terminal cisternae/junctional SR, and are the location where ion channels necessary for calcium ion absorption are most abundant. These processes are explained in more detail below and are fundamental for the process of excitation-contraction coupling in skeletal, cardiac and smooth muscle. The SR contains ion channel pumps, within its membrane that are responsible for pumping Ca2+ into the SR.
About this result
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.
Ontological neighbourhood
Related lectures (12)
Quantum Mechanics: Eigenfunctions and Operators
Explores eigenfunctions, operators, and their role in quantum mechanics.
Relative Stability Towards Diffeomorphisms in Deep Nets
Explores the impact of relative stability towards diffeomorphisms in deep neural networks and its correlation with performance.
Protein Translocation in the Endoplasmic Reticulum
Explains protein translocation in the endoplasmic reticulum, focusing on signal peptides and co-translational transfer across the ER membrane.
Show more
Related publications (32)

Trans-anethole Induces Thermogenesis via Activating SERCA/SLN Axis in C2C12 Muscle Cells

Sulagna Mukherjee

Recently, adaptive non-shivering thermogenesis has attracted considerable attention because it can elevate energy expenditure and help treat obesity. Despite the numerous reports related to UCP1-driven thermogenesis, little is known regarding UCP1-independ ...
KOREAN SOC BIOTECHNOLOGY & BIOENGINEERING2022

GRASP55 regulates intra-Golgi localization of glycosylation enzymes to control glycosphingolipid biosynthesis

Giovanni D'Angelo, Charlotte Julie Caroline Gehin, Laura Capolupo, Riccardo Rizzo

The Golgi apparatus, the main glycosylation station of the cell, consists of a stack of discontinuous cisternae. Glycosylation enzymes are usually concentrated in one or two specific cisternae along the cis-trans axis of the organelle. How such compartment ...
WILEY2021

Acute RyR1 Ca2+ leak enhances NADH-linked mitochondrial respiratory capacity

Johan Auwerx, Umberto De Marchi

Sustained ryanodine receptor (RyR) Ca2+ leak is associated with pathological conditions such as heart failure or skeletal muscle weakness. We report that a single session of sprint interval training (SIT), but not of moderate intensity continuous training ...
NATURE PORTFOLIO2021
Show more
Related concepts (20)
Muscle contraction
Muscle contraction is the activation of tension-generating sites within muscle cells. In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such as when holding something heavy in the same position. The termination of muscle contraction is followed by muscle relaxation, which is a return of the muscle fibers to their low tension-generating state.
Muscle cell
A muscle cell is also known as a myocyte when referring to either a cardiac muscle cell (cardiomyocyte) or a smooth muscle cell, as these are both small cells. A skeletal muscle cell is long and threadlike with many nuclei and is called a muscle fiber. Muscle cells (including myocytes and muscle fibers) develop from embryonic precursor cells called myoblasts. Myoblasts fuse from multinucleated skeletal muscle cells known as syncytia in a process known as myogenesis.
Cardiac muscle
Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate muscle tissues, with the other two being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that constitutes the main tissue of the wall of the heart. The cardiac muscle (myocardium) forms a thick middle layer between the outer layer of the heart wall (the pericardium) and the inner layer (the endocardium), with blood supplied via the coronary circulation.
Show more