HUBS 191 Lecture 8 Flashcards
what are the three types of muscle
skeletal muscle - cardiac muscle - smooth muscle
what are the functions of skeletal muscles
generate force - protect soft internal organs - voluntary control of major openings - converting energy into heat
what is a muscle comprised of (in bundles)
myofibrils
what are myofibrils made of
repeating units called sarcomeres
what is the name of the cell membrane that lines the muscle fibre
sarcolemma
what are sarcomeres made up of
contractile proteins or myofilaments - actin (thin filaments) and myosin (thick filaments)
what are transverse tubules (T-tubules) and what is their function
tube like extensions of the sarcolemma that conduct electrical signals (action potentials) Deep into the core of the fibre.
what is the sarcoplasmic reticulum (SR)
an extensive membrane network associated with the T-tubules at regular intervals
what is the function of the SR
to take up and store calcium while the muscle is relaxed, and then release calcium into the cytoplasm when the muscle contracts
what is excitation coupling (EC-coupling)
the pairing of a signalling event (excitation of the muscle cell) with a mechanical event (contraction of the muscle cell)
what is the function of the voltage gated sensor (DHPR)
receives signals from the t-tubules and interacts with ryanodine receptors
what is the function of the ryanodine receptor (RyR)
a passive calcium channel on the SR that can open to allow Ca2+out into the cell
what is the function of the SR calcium-ATPase (SERCA)
this is an active calcium pump that uses ATP to move the Ca2+ back into the SR against it’s concentration gradient ending the excitation
what initiates EC coupling
when a signal is transmitted down the T-tubules from the nerves running throughout the muscle
what order do the three key proteins function in when a signal is transmitted through the cell via the t-tubules
voltage sensor (DHPR)
ryanodine (RyR)
SR calcium-ATPase (SERCA)
what are individual muscle cells called
muscle fibres
what is a bundle of muscle fibres called
a fascicle
what is a bundle of fascicles called
a muscle
fibres, fascicles and muscle all pointing in the same direction contain blood vessels and nerves. what are they sheathed in
connective tissue
