The sarcomere and more Flashcards
How does actin and myosin move when contraction takes place
They slide past one another. They don’t change the length
Titin and nebulin movement
Titin and nebulin are accessory proteins. Titin spans the distances from one Z disk to the neighboring M line. Nebulin, lying along the thin filaments, attaches to a z disk but does not extend to the M line.
force created by muscle is called
Muscle tension
weight or force opposing contraction
load
creation of tension in muscle
contraction=
Relaxation=
release of tension
What are the major steps leading up to skeletal muscle contraction
- Events at the neuromuscular junction
- Excitation-contraction (E-C) coupling
- Ca2+ signal
- Contraction-relaxation cycle
and then 2 results either a muscle twitch or sliding filament theory
What is the sliding filament theory of contraction
It is when actin and myosin slide past each other during contraction
- Overlapping actin and myosin myofibrils
- Fibrils are fixed-length
- Slide past each other in energy-dependent process
What are the steps to the sliding filament theory of contraction?
Function is to move Move actin filaments
myosin crossbridges
Myosin crossbridge have powerstrokes, what do they do?
Myosin crossbridge swivels and pulls actin toward M line
What happens at the end of a Powerstroke?
-Myosin releases actin and resets and binds another actin
-Heads are not released in unison
How often is a powerstroke repeated
multiple times
What does Myosin ATPase do?
Energy places the myosin head into the “cocked position”
When myosin comes into contact with actin, the pull is initiated
What happens when myosin and actin come into contact?
The pull is initiated
