sarcomere is defined by
structure between two Z discs
What is the A band
anisotropic
(dark)
lenght of the thick filament
I Band
isotropic (lighter)
distance between two thick filaments
which protein blocks the active sites on the actin at rest?
tropomyosin
Troponin has which binding sites?
Toponin C: Ca is binding
Troponin T: binding to Tropomyosin
Troponin I (inhibitory): binds to actin
Myosin contains of
and has which activity
tail, neck, head
ATPase activity
At the neuromusc synapsis which channels open after depolarization of the sarkolemma through sodium influx?
voltage sensitive calcium channels
on the neuromuskular junction, which structures does ACh bind to?
nicotinergic receptor 1 activates ion channel: allows massive influx of Sodium and little bit K out
What are the two things maintaining resting membrane potential?
ATP pump pumpipng 3Na out and 2K in
K leaking channels: K leaks out
What is the Ryanodine Receptor?
OPens up Sarkolemma for outflow of Calcium when stimulated by DHP Receptor on the T Tubule (this is stimulated by membrane depolarization)
For muscle contraction Calcium released from the sarkolemma binds where?
binds to troponin
- > removal of tropomyosin from the actin binding sites
- >
ATP is needed in muscle contraction for
- detachement of actin from myosin and bending of the actin neck (by phosphate) and leads to “power stroke” and shortening of the muscle
- additional ATP also needed to detach actin from myosin and go back to resting state
How is calcium removed from the cytosol of muscle cells after contraction?
energy depended Ca pump on the sarcoplasmatic reticulum
