Muscles Flashcards
What are the 3 key proteins in EC coupling.
Troponin Complex, Ryanodine Receptor (RyR), Dihydropyridine Receptor (DHPR)
What is tetanus
When the muscle fibre is stimulated so fast that it cannot relax.
What are the three main types of muscle in the human body?
Smooth muscle, cardiac muscle, and skeletal muscle.
What is the primary job of skeletal muscle?
To develop force by contracting (shortening).
What are secondary jobs of skeletal muscle?
Support and protection for soft internal organs, provide voluntary control over major openings, and convert energy to heat to maintain core temperature.
What are muscle fibres?
Individual muscle cells that gather into bundles called fascicles.
What is the role of connective tissue in muscle structure?
Connective tissue gathers to form tendons, which connect muscles to bones.
What are myofibrils?
Bundles within a muscle fibre made of repeating units known as sarcomeres.
What are the two types of contractile proteins in sarcomeres?
Actin (thin filaments) and myosin (thick filaments).
What is the sarcolemma?
The cell membrane of a muscle fibre.
What is the function of transverse tubules (T-tubules)?
To conduct electrical signals (action potentials) deep into the core of the fibre.
What is the sarcoplasmic reticulum (SR)?
An extensive membrane network associated with T-tubules that stores calcium (Ca2+) and releases it during muscle contraction.
What is excitation-contraction coupling (EC-coupling)?
The pairing of a signaling event (excitation of the muscle cell) with a mechanical event (contraction of the muscle cell).
What are the three key proteins involved in excitation?
DHPR (voltage-gated sensor), RyR (ryanodine receptor), and SERCA (SR Calcium-ATPase).
How does the excitation signal lead to muscle contraction?
The signal activates the DHPR, which interacts with RyR, causing calcium to be released from the SR into the cell, activating myofilaments and causing contraction.
How is relaxation of a muscle cell achieved?
Calcium is pumped back into the SR by the SERCA pump, stopping the signaling event and allowing the muscle to relax.
What are the key components of skeletal muscle structure at the tissue level?
Skeletal muscle fibres organized into fascicles and muscles, associated with nerves, vessels, and connective tissue.
What gives skeletal muscle its striated appearance?
The organization of myofilaments within sarcomeres.
What is the consequence of a signal arriving at the cell through the T-tubules during EC-coupling?
It triggers the release of calcium from the SR, leading to muscle contraction.
What happens during the relaxation phase of muscle contraction?
The SERCA pump moves calcium into the SR, allowing the muscle to relax.
What does muscle tension depend on?
- Number of muscle fibres recruited
- The rate at which the muscle is stimulated
