sarcolemma

Examples of sarcolemma in the following topics:

• Excitation–Contraction Coupling

  • It is the link (transduction) between the action potential generated in the sarcolemma and the start of a muscle contraction .
  • The area of the sarcolemma on the muscle fiber that interacts with the neuron is called the motor-end plate.
  • The motor end plate possesses junctional folds: folds in the sarcolemma that create a large surface area for the neurotransmitter to bind to receptors.
  • The depolarization then spreads along the sarcolemma and down the T tubules, creating an action potential.

• Skeletal Muscle Fibers

  • The sarcolemma of myocytes contains numerous invaginations (pits) called transverse tubules which are usually perpendicular to the length of the myocyte.
  • Myofibrils run parallel to the myocyte and typically run for its entire length, attaching to the sarcolemma at either end.
  • A skeletal muscle cell is surrounded by a plasma membrane called the sarcolemma with a cytoplasm called the sarcoplasm.

• Muscle Development

  • These cells remain adjacent to a muscle fiber, situated between the sarcolemma and the endomysium (the connective tissue investment that divides the muscle fascicles into individual fibers).
  • Satellite cells are located between the basement membrane and sarcolemma (cell membrane) of individual muscle fibers.

• Myocardial Thickness and Function

  • Each muscle fiber connects to the plasma membrane (sarcolemma) with distinctive tubules (T-tubule).
  • At these T-tubules, the sarcolemma is studded with a large number of calcium channels which allow calcium ion exchange, at a rate that occurs much faster compared to that of the neuromuscular junction in skeletal muscle.

• Microscopic Anatomy

  • Sarcomeres are connected to a plasma membrane, called a sarcolemma, by T-tubules, which speed up the rate of depolarization within the sarcomere.

• Short-Term Chemical Control

  • When stimulated a signal transduction cascade leads to increased intracellular calcium from the sarcoplasmic reticulum through IP3 mediated calcium release, as well as enhanced calcium entry across the sarcolemma through calcium channels.

• Peripheral Motor Endings

  • Detailed view of a neuromuscular junction: (1) Presynaptic terminal; (2) Sarcolemma; (3) Synaptic vesicle; (4) Nicotinic acetylcholine receptor; (5) Mitochondrion.