lecture 8 skeletal muscle structure and function Flashcards
How does the signal get inside the cell from the voltage gated sensor and the ryanodine receptor?
Once the voltage gated receptor has engaged the ryanodine receptor it causes the release of Ca from the sacroplasmic reticulum where they move through the ryanodine receptor passively down their concentration gradient into the cell.
How does Ca entering the cell cause a muscle contraction?
The ca diffuses througout the cell which causes the myofilaments to contract which results in a muscle contraction.
How is a EC coupling signal stopped so the muscle can return to relaxation?
The SR calcium ATPase senses the high level of calcium in the cell. This causes it to break down ATP for energy to move calcium ions against their concentration gradient out of the cell (active transport). The removal of the calcium stops the signal so the muscles can return to being relaxed.
Name and describe the types of muscle in the body? What do they have in common?
smooth- lines hollow organs (eg gut and blood vessels), an involuntary muscle. Cardiac- only located in the heart, an involuntary muscle. Skeletal muscle, applies force to bone to allow for posture and body movement, these are typically voluntary muscles. All muscles are made of cells called fibres, with a primary function of generating force via contraction
Name the three key proteins involved in excitation
voltage gated senso, ryanodine receptor, SR calcium ATPase
Name the whole muscle structure
individual muscle cells = fibres, bundles of fibres= fascicles, bundles of fascicles= muscles.
What happens when a signal is sent to the muscle?
The signal moves through the transverse tubulars, the voltage gated sensor detects a change in voltage which causes it to release its protruding bit and engage the ryanodine receptor.
What is Excitation- contracting coupling (EC coupling)?
the pairing of a signalling event (excitation of muscle cell) with a mechanical event ( contraction of a muscle cell)
