Retrieving "Muscle Contraction" from the archives

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1. Calcium

   Linked via "muscle contraction"

   In Animalia
   In vertebrates, calcium ions ($\text{Ca}^{2+}$) are vital components of the skeletal structure, forming the crystalline hydroxyapatite ($\text{Ca}{10}(\text{PO}4)6(\text{OH})2$) in bones and teeth. Beyond structural support, calcium acts as a critical secondary messenger in cellular signaling pathways, re…

2. Metazoan

   Linked via "muscle contraction"

   Cellular Components and Energy Dynamics
   Metazoan cells are bounded by a lipid bilayer and possess complex internal organelles. Mitochondria, the primary site of aerobic respiration, are crucial for generating Adenosine Triphosphate (ATP). However, the actual energy currency utilized in most high-demand processes, such as axonal firing or [muscle contraction](/entries/mus…

3. Sarcoplasmic Reticulum

   Linked via "muscle contraction"

   The sarcoplasmic reticulum (SR)/) is a specialized form of the endoplasmic reticulum found in the cytoplasm of striated muscle fibers (skeletal and cardiac muscle cells). Its primary, universally acknowledged function is the sequestration, storage, and regulated release of calcium ions ($\text{Ca}^{2+}$), which are the crucial second messengers initiating muscle contraction via the [sliding filament t…