Table of Contents
- 1 What is the order of events during sarcomere contraction?
- 2 What is the sequence of events during a skeletal muscle contraction?
- 3 How does a sarcomere contract?
- 4 What structures mark the ends of a sarcomere?
- 5 What kind of structure is found in the sarcomere?
- 6 Which is responsible for coupling excitation to contraction?
What is the order of events during sarcomere contraction?
Depolarisation and calcium ion release. Actin and myosin cross-bridge formation. Sliding mechanism of actin and myosin filaments. Sarcomere shortening (muscle contraction)
What is the sequence of events during a skeletal muscle contraction?
The sequence of events in twitch skeletal muscle involves: (1) initiation and propagation of an action potential along the plasma membrane, (2) spread of the potential throughout the transverse tubule system (T-tubule system), (3) dihydropyridine receptors (DHPR)-mediated detection of changes in membrane potential, (4) …
What is the structure of the sarcomere?
The sarcomere is the fundamental unit of contraction and is defined as the region between two Z-lines. Each sarcomere consists of a central A-band (thick filaments) and two halves of the I-band (thin filaments). Light gray circles demark thick (myosin) filaments and black circles demark thin (actin) filaments.
Which of the following marks the boundaries of a sarcomere?
Z-lines mark the boundaries of the sarcomeres. The dark staining region in the centre of the sarcomere is called the A (anisotropic) band. The lighter staining band, through which the Z-line passes is called the I (isotropic) band. A diagram of a muscle sarcomere is shown below.
How does a sarcomere contract?
For a muscle cell to contract, the sarcomere must shorten. However, thick and thin filaments—the components of sarcomeres—do not shorten. Instead, they slide by one another, causing the sarcomere to shorten while the filaments remain the same length.
What structures mark the ends of a sarcomere?
Z discs mark the end of the sarcomeres.
What is the correct description of a sarcomere?
Sarcomere are the basic unit of striated muscle tissue. It forms the repeating unit between two Z lines. Skeletal muscles is made up of tubular muscle cells. Each muscle fibers contain numerous tubular myofibrils.
How are sarcomeres able to initiate large movements?
Sarcomeres are able to initiate large, sweeping movement by contracting in unison. Their unique structure allows these tiny units to coordinate our muscles’ contractions.
What kind of structure is found in the sarcomere?
This calls for a molecular structure that can shorten along with the shortening muscle. Such requisites are found in the sarcomere. Upon closer inspection, skeletal muscle tissue gives off a striped appearance, called striation.
Which is responsible for coupling excitation to contraction?
The structures responsible for coupling this excitation to contraction are the T tubules and sarcoplasmic reticulum (SR). The T tubules are extensions of the sarcolemma and thus carry the action potential along their surface, conducting the wave of depolarization into the interior of the cell.