What are the steps of excitation?
The EC-coupling cycle involves the following sequence of events: (1) depolarization of the plasma membrane and its membrane invaginations (the t-tubular system) by an action potential; (2) transduction of the depolarization signal to the sarcoplasmic reticulum (SR) membrane; (3) activation of Ca2+ release from the SR …
What is calcium’s function during muscle contraction?
Calcium is required by two proteins, troponin and tropomyosin, that regulate muscle contraction by blocking the binding of myosin to filamentous actin. In a resting sarcomere, tropomyosin blocks the binding of myosin to actin.
What happens at the sarcolemma?
At each end of the muscle fiber, the surface layer of the sarcolemma fuses with a tendon fiber, and the tendon fibers, in turn, collect into bundles to form the muscle tendons that adhere to bones. The sarcolemma generally maintains the same function in muscle cells as the plasma membrane does in other eukaryote cells.
What is Caveolae in smooth muscle?
Caveolae are 50- to 90-nm flask-shaped invaginations that appear in rows in periodic register along the longitudinal axis of the smooth muscle membrane, interspersed by regions of dense bodies anchoring the cytoskeleton, as illustrated in Fig. 1A.
Which of the following describes the relaxation phase?
Which of the following describes the relaxation phase? The sarcomeres are decreasing in length, and the force generated increases. The sarcomeres are increasing in length, and the force generated decreases. The sarcomeres are decreasing in length, and the force generated decreases.
Which of the following steps in excitation-contraction occurs first?
Which of the following steps in excitation-contraction occurs first? Acetylcholine is released from the motor neuron and binds to nicotinic cholinergic receptors on the motor end plate. Which of the following processes in skeletal muscle cells requires ATP?
How do these altered Ca2+ levels affect the position of the actin and myosin filaments Why How?
How do these altered Ca2+ levels affect the position of the actin and myosin filaments? Why/how? Because the Troponin never releases the Tropomysin, the actin and myosin never stop touching long periods of time, thus creating stif and rigid muscles. need more of, and where?
What happens during Tetany?
Tetany is a symptom characterized by the involuntary contraction of muscles that usually results from low calcium levels in the blood (i.e., hypocalcemia). Common symptoms of tetany include numbness around the mouth, muscle cramps, and paresthesias affecting the hands and feet.
What is sarcolemma in nervous system?
Muscle and Nerve Development in Health and Disease 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.
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 is the function of caveolae?
Caveolae have been described to function in endocytosis and transcytosis (a specialized form of endocytosis) and in maintaining membrane lipid composition, as well as acting as signaling platforms.
Why are caveolae important?
90, 165, 187). Caveolae represent a morphologically identifiable subset of lipid rafts. They contain the coat protein caveolin, which is essential for the invagination of the plasma membrane through a largely unknown process, giving them their characteristic flasklike appearance.