Terminal cisternae: Difference between revisions

Latest revision as of 16:25, 16 February 2025

Terminal Cisternae[edit]

The terminal cisternae are specialized structures within the sarcoplasmic reticulum of skeletal muscle cells. They play a crucial role in the storage and release of calcium ions (Ca__), which are essential for muscle contraction.

Structure[edit]

Terminal cisternae are enlarged areas of the sarcoplasmic reticulum that are located adjacent to the T-tubules (transverse tubules). Together, a T-tubule and two terminal cisternae form a structure known as a triad. This arrangement is critical for the rapid transmission of the action potential from the T-tubules to the sarcoplasmic reticulum, facilitating the release of calcium ions.

Function[edit]

The primary function of the terminal cisternae is to sequester and release calcium ions. When a muscle cell is stimulated by an action potential, the signal travels down the T-tubules and triggers the opening of calcium channels in the terminal cisternae. This results in a rapid influx of calcium ions into the cytosol, initiating the interaction between actin and myosin filaments, which leads to muscle contraction.

Role in Muscle Contraction[edit]

During muscle contraction, the release of calcium ions from the terminal cisternae is a key step. The calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from the binding sites on actin filaments. This allows the myosin heads to attach to actin and perform the power stroke, resulting in muscle contraction.

After contraction, calcium ions are actively pumped back into the terminal cisternae by calcium ATPase pumps, allowing the muscle to relax.

Related Pages[edit]

Template:Skeletal muscle

@@ Line 1: / Line 1: @@
-Terminal cisternae are specialized regions within muscle cells that play a crucial role in muscle contraction. These structures are found in close association with the T-tubules in skeletal muscle fibers and are essential for the regulation of calcium ions during muscle contraction.
+== Terminal Cisternae ==
-== Structure ==
+[[File:Blausen_0801_SkeletalMuscle.png|thumb|right|Diagram of skeletal muscle showing terminal cisternae]]
-Terminal cisternae are enlarged regions of the sarcoplasmic reticulum, a specialized type of endoplasmic reticulum found in muscle cells. They are located on either side of the T-tubules, forming a triad structure along with the T-tubule. The terminal cisternae store and release calcium ions, which are necessary for muscle contraction.
-== Function ==
+The '''terminal cisternae''' are specialized structures within the [[sarcoplasmic reticulum]] of [[skeletal muscle]] cells. They play a crucial role in the storage and release of [[calcium ions]] (Ca__), which are essential for muscle contraction.
-During muscle contraction, an action potential travels along the T-tubules, causing the release of calcium ions from the terminal cisternae into the cytoplasm of the muscle cell. The calcium ions bind to the protein complex troponin, which initiates the contraction of the muscle fibers by allowing the myosin and actin filaments to interact.
-== Role in Muscle Contraction ==
+=== Structure ===
-The release of calcium ions from the terminal cisternae is a key step in the process of muscle contraction. The calcium ions bind to troponin, which leads to a conformational change in the protein complex tropomyosin, exposing the binding sites on the actin filaments. This allows the myosin heads to bind to the actin filaments and generate the force necessary for muscle contraction.
-== Clinical Significance ==
+Terminal cisternae are enlarged areas of the sarcoplasmic reticulum that are located adjacent to the [[T-tubules]] (transverse tubules). Together, a T-tubule and two terminal cisternae form a structure known as a [[triad (muscle)|triad]]. This arrangement is critical for the rapid transmission of the action potential from the T-tubules to the sarcoplasmic reticulum, facilitating the release of calcium ions.
-Disruption of the function of the terminal cisternae can lead to muscle disorders such as malignant hyperthermia, a rare but potentially life-threatening condition triggered by certain anesthetic agents. In malignant hyperthermia, there is uncontrolled release of calcium ions from the sarcoplasmic reticulum, leading to sustained muscle contractions and a dangerous increase in body temperature.
-[[Category:Muscular system]]
+=== Function ===
-[[Category:Cell biology]]
-[[Category:Medical terminology]]
+The primary function of the terminal cisternae is to sequester and release calcium ions. When a muscle cell is stimulated by an action potential, the signal travels down the T-tubules and triggers the opening of calcium channels in the terminal cisternae. This results in a rapid influx of calcium ions into the [[cytosol]], initiating the interaction between [[actin]] and [[myosin]] filaments, which leads to muscle contraction.
-{{medicine-stub}}
+=== Role in Muscle Contraction ===
+During muscle contraction, the release of calcium ions from the terminal cisternae is a key step. The calcium ions bind to [[troponin]], causing a conformational change that moves [[tropomyosin]] away from the binding sites on actin filaments. This allows the myosin heads to attach to actin and perform the power stroke, resulting in muscle contraction.
+After contraction, calcium ions are actively pumped back into the terminal cisternae by [[calcium ATPase]] pumps, allowing the muscle to relax.
+== Related Pages ==
+* [[Sarcoplasmic reticulum]]
+* [[T-tubule]]
+* [[Calcium ion]]
+* [[Muscle contraction]]
+* [[Actin]]
+* [[Myosin]]
+{{Skeletal muscle}}
+[[Category:Muscle physiology]]