Skeletal Muscle 2 Flashcards
What is the resting membrane potential of muscle cells?
-80 to -90 mV
What is the definition of a motor unit?
The nerve and all of the muscle fibers it innervates
What is another name for the Neuromuscular Junction?
Motor end plate
What is the neuromuscular transmitter?
Acetylcholine
What is the Ach receptor that is part of the postsynaptic motor unit?
Nicotinic Acetylcholine Receptor
When the AP travels down the axon and the nerve releases Ach what happens in the muscle cell?
An end plate potential is formed which leads to a AP in the muscle fiber
What enzyme breaks up Ach after it is released into the NMJ cleft?
Acetylcholinesterase
What event does tetradotoxin block?
the AP at the axon terminal
What event does botulinum toxin block?
ACh release
What event does curare/succynylcholine block
ACh binding
What event does Nerve Gases and Organophosphates block?
ACh breakdown
What event do hemicholinum drugs block?
Choline uptake
What feature of cardiac muscle cells allows for the spread of APs throughout the heart?
Gap junctions
What is the key regulator in terms contraction and force or contraction in cardiac muscle?
Calcium influx
What are the 2 sources of calcium for cardiac muscle cells
Extracellularly
Calcium pool in the SR
What are the 3 primary functions of ATP in muscle cells?
Energy for contraction
Detachment of Actin-Myosin Complex
Energy for SR Ca2+ uptake
Where does ADP get its phosphate group to become ATP?
Creatine Phosphate
What is oxygen debt?
The extra oxygen needed after exercising
What is the largest contributor to oxygen debt?
Lactic acid
What two factors determine the amount of tension created by a muscle?
Muscle fiber length
AP Frequency
What two factors affect the number of muscle fibers
Number of muscle fibers per motor unit
Number of active motor units
What is a muscle twitch?
Contraction and Relaxation of a skeletal muscle from a single stimulus
What is summation?
When a second contraction is signaled before the muscle has fully relaxed….power of second will be added to first
What is tetanus
When signals are come at a frequency that doesn’t allow for any relaxation
