Table of Contents
What is the distance between thin filaments?
~0.95 µm
Thin filaments are more accurately modeled as bipartite structures with the following concatenated segments: (i) a constant-length, nebulin-coated thin filament core region (‘proximal segment’) starting at the Z-line and continuing to a distance of ~0.95 µm away from the Z-line; (ii) a variable-length, nebulin-free.
What is the space between the thick and thin filaments?
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).
What is apart of the thin filament?
Thin filaments are composed primarily of the contractile protein actin. The actin molecules contain active sites to which myosin heads will bind during contraction. The thin filaments also contain the regulatory proteins called tropomyosin and troponin, which regulate the interaction of actin and myosin.
What is the distance between two Z discs?
sarcomere
A sarcomere is defined as the distance between two consecutive Z discs or Z lines; when a muscle contracts, the distance between the Z discs is reduced.
Is Titin a thick or thin filament?
Titin is a huge, 4.2 MDa, filamentous protein located in the sarcomere of striated muscle. Extending from its N-terminus anchored in the Z-disc to its C-terminus bound to thick filaments in the M-band, titin is largely responsible for the passive stiffness of the myocardium exhibited during diastolic filling.
What are the steps of muscle contraction?
What are the 5 steps of muscle contraction?
- exposure of active sites – Ca2+ binds to troponin receptors.
- Formation of cross-bridges – myosin interacts with actin.
- pivoting of myosin heads.
- detachment of cross-bridges.
- reactivation of myosin.
What does the Z line do during contraction?
When (a) a sarcomere (b) contracts, the Z lines move closer together and the I band gets smaller. The A band stays the same width and, at full contraction, the thin filaments overlap. When a sarcomere shortens, some regions shorten whereas others stay the same length.
What are red muscles rich in?
myoglobin
Red muscles are red because of the presence of dense capillaries that are rich in myoglobin and mitochondria. One of the main difference between red and white muscle fibres is the colour which is deep red for red muscles because of myoglobin which is present in the sarcoplasm (cytoplasm) of the muscle fibre.