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The sarcoplasmic reticulum is a network of the 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 ...
The endoplasmic reticulum is found in most eukaryotic cells and forms an interconnected network of flattened, membrane-enclosed sacs known as cisternae (in the RER), and tubular structures in the SER. The membranes of the ER are continuous with the outer nuclear membrane. The endoplasmic reticulum is not found in red blood cells, or spermatozoa.
SERCA is a P-type ATPase. [1] It resides in the sarcoplasmic reticulum (SR) within myocytes. [1] It is a Ca 2+ ATPase that transfers Ca 2+ from the cytosol of the cell to the lumen of the SR. [1]
The unusual microscopic anatomy of a muscle cell gave rise to its terminology. The cytoplasm in a muscle cell is termed the sarcoplasm; the smooth endoplasmic reticulum of a muscle cell is termed the sarcoplasmic reticulum; and the cell membrane in a muscle cell is termed the sarcolemma. [9]
It has a Golgi apparatus near the nucleus, mitochondria just inside the cell membrane , and a smooth endoplasmic reticulum (specialized for muscle function and called the sarcoplasmic reticulum). [7] While sarcoplasm and myoplasm, viewed etymologically, might seem to be synonyms, they are not.
The concentration of calcium within muscle cells is controlled by the sarcoplasmic reticulum, a unique form of endoplasmic reticulum in the sarcoplasm. Muscle cells are stimulated when a motor neuron releases the neurotransmitter acetylcholine , which travels across the neuromuscular junction (the synapse between the terminal button of the ...
Terminal cisternae are discrete regions within the muscle cell. They store calcium (increasing the capacity of the sarcoplasmic reticulum to release calcium) and release it when an action potential courses down the transverse tubules, eliciting muscle contraction. [2]
Excitation-contraction coupling in myocardium relies on sarcolemma depolarization and subsequent Ca 2+ entry to trigger Ca 2+ release from the sarcoplasmic reticulum.When an action potential depolarizes the cell membrane, voltage-gated Ca 2+ channels (e.g., L-type calcium channels) are activated.