Title: Sarcolemma - Definition and Examples - Biology Online Dictionary
Headings: Sarcolemma Definition
Sarcolemma
Table of Contents
Sarcolemma Definition
Characteristics of Sarcolemma
Sarcolemma Structure
The Function of the Sarcolemma
What initiates an action potential on a muscle cell?
The Importance of T-tubules and Triads
Dysfunctional Sarcolemma
Biological Importance of Sarcolemma
References:
Quiz

Content: As the muscle cell membrane, the sarcolemma functions as a barrier between the extracellular and intercellular parts of the muscle fiber cells. It can do this because the membrane is lipid in nature, thereby it separates the fluids of the intracellular and extracellular spaces and only allows water in through aquaporin channels. The membrane contains ion pumps as in other cell membranes in the body, allowing for ion gradients to be created to use up ATP. The T-tubule membrane portion of the sarcolemma is highly plastic and therefore provides stability during muscle contraction. Studies have also shown that T tubules are involved in water balance and cell volume regulation, recovery from muscle fatigue as well as transport of molecules. The T-tubules also have an important role involved in the transmission of action potentials which will be discussed later. The structure and design of the sarcolemma are essential for receiving and conducting stimuli. During the resting state, the sarcolemma keeps the inside of the muscle fiber at a negative potential compared to the extracellular fluid. It pumps out more sodium ions than it takes in potassium ions. Therefore, the sarcoplasm has a higher potassium concentration but a lower sodium concentration than the extracellular space.