skeletal muscle Flashcards
What type of cells are muscles composed of
1.muscle fibres
2.vascular cells
3.fibroblasts
4.satellite cells
Describe the creatinephosphate energy system
provides energy very fast to form atp from adp but only lasts 1-2 seconds
Describe the glycosis energy system
Energy from glucose in the absence of oxygen
Describe the oxidative phosphorylation energy system
Energy from glucose or fat in the presence of oxygen
describe the parts of a muscle fibre from smallest to largest
1.muscle
2.fascicles
3.muscle fibres
4.myofibrills
5.thick and thin filaments
Describe the neuromuscular junction
1.motor neurons action potential arrives at the axon terminal-depolarizes plasma membrane.
2.opening calcium channels-calcium ions diffuse into axon terminal-calcium binds to protein.
3.synaptic vesicles release achetycholine.
4.ach diffuses from axon terminal to motor end plate.
What is excitation contraction coupling
The sequence of events where the action potential in the plasma membrane activate the force generating mechanisms
Describe a relaxed muscle in excitation contraction coupling
Low calcium means the cross bridge cannot bind with actin as tropomyosin is covering the binding site
Describe an active muscle during excitation contraction coupling
High calcium means calcium binds to troponin and the tropomyosin moves away meaning the cross bridge can bind to the actin
What are the two proteins that are responsible for linking the action potential and calcium
1.dihdropyridine
2.ryanodine
what are the 4 stages of the cross bridge cycle (sliding filament theory)
1.Energised myosin cross bridges on the thick filament bind to actin.
2.Cross bridge binding triggers the release of atp products from myosin causing angular movement.
3.Atp bind to myosin breaking the link between actin and myosin.
4.ATP bound to myosin is split energizing the myosin cross bridge.
What is tension
The force that a muscle exerts on a joint when it is contracting
What is load
The force that is exerted on a muscle
Describe the load velocity relationship
In the absence of a load the muscle can reach its maximum shortening velocity.
Describe the mecahnisms involved in muscle fatigue
1.Conduction failure
2.lactic acid build up
3.Inhibition of cross bridge cycling
4.Fuel substrates
5.Central command fatigue
