What is sarcolemma and Plasmalemma?
The sarcolemma is a specialized cell membrane which surrounds striated muscle fiber cells. Sometimes called the myolemma, the sarcolemma is similar to a typical plasma membrane but has specialized functions for the muscle cell.
What is the sarcolemma composed of?
The sarcolemma (sarco (from sarx) from Greek; flesh, and lemma from Greek; sheath) also called the myolemma, is the cell membrane of a muscle cell. It consists of a lipid bilayer and a thin outer coat of polysaccharide material (glycocalyx) that contacts the basement membrane.
What are 3 functions of the sarcolemma?
Sarcolemma. The sarcolemma or cell membrane is the site where calcium enters and leaves the cell through a distribution of ion channels, transporters, and pumps. The T-tubules are invaginations of the sarcolemma that form a permeability barrier between the cytosol and the extracellular space (Brette and Orchard, 2003).
What causes repolarization of the sarcolemma?
This is called repolarization, during which sodium channels close and potassium channels open. Because positive potassium ions (K+) move from the intracellular space to the extracellular space, this allows the inside of the cell to again become negatively charged relative to the outside.
What does Plasmalemma mean?
the cell membrane
Plasmalemma is a less common term for the cell membrane—the thin layer that encloses a cell’s cytoplasm, which is the substance between the membrane and the nucleus. In the context of biology, plasma is used as another word for cytoplasm. The lemma in plasmalemma comes from a Greek word that means “husk.”
What is the Sarcomella?
The sarcolemma is the plasma membrane of the muscle cell and is surrounded by basement membrane and endomysial connective tissue. The sarcolemma is an excitable membrane and shares many properties with the neuronal cell membrane.
Is sarcolemma the same as plasma membrane?
The sarcolemma anatomy can be defined as the plasma membrane of a muscle cell or the plasma membrane of a muscle fiber. Muscle cells are also known as muscle fibers due to their long, cylindrical shape.
Which cells contain sarcoplasm?
Sarcoplasm is the cytoplasm of a muscle cell. It is comparable to the cytoplasm of other cells, but it contains unusually large amounts of glycogen (a polymer of glucose), myoglobin, a red-colored protein necessary for binding oxygen molecules that diffuse into muscle fibers, and mitochondria.
What are the two functions of the sarcolemma?
Biologically, the sarcolemma has many functions and is more than just a cell membrane. As well as allowing endo- and exocytosis, the sarcolemma acts as a barrier and a link to the cytoskeleton of the extracellular matrix. It is also an electrical insulator.
What does the Sarcoplasm do?
The sarcoplasm plays a critical role in muscle contraction as an increase in Ca2+ concentration in the sarcoplasm begins the process of filament sliding. A decrease in Ca2+ in the sarcoplasm subsequently ceases filament sliding. The sarcoplasm also aids in pH and ion balance within muscle cells.
