Muscle Contraction (Exam 3) Flashcards
What is electrical potential?
Difference in net charge
What is the extracellular fluid made of?
High concentration of Na+ and Cl-
What is the intracellular fluid made of?
High concentration of K+
What is the resting potential of the neuron and muscle membrane?
-90 mV
What is the resting potential maintained by?
Na+/K+ ATPase
What is action potential?
Momentary changed in electrical membrane potential
What is the action potential in neurons?
Nerve impulse
What type of process is action potential doing?
Electrochemical
How does action potential occur? (3)
Depolarization
Repolarization, re-establishin resting potential
Redistributing ions, maintaining resting potential
What is depolarization?
Sudden and drastic increase in permeability of Na+ causing reversing potential
What is repolarization?
At max reverse, K+ outward diffusion re-establishing potential
What does the depolarization current do?
Stimulate N+ channels in the adjacent region, depolarizing the next region
How does redistributing ions occur?
Na+/K+ ATPase redistributes Na+ and K+ hile maintaining resting potential
What does everything at the neuromuscular junction start with?
A sudden increase in Na+ permeability
How long do action potentials last?
0.5 to 1 ms
What is acetyl choline?
Neurotransmitter increasing Na+ permeability released at motor end plate of neuron contracting sarcolemma
What are 7 events at the neuromuscular junction?
- Action potential travels to axon terminal of motor neuron
- Ca++ diffuses into axon terminal
- Acetylcholine released
- Acetylcholine binds to receptors at the motor endplate
- Na+ enters muscle fiber and K+ exits (depolarization)
- Action potential propagates along the sarcolemma to T tubules
- Removal of acetylcholine by acetylcholine esterase
Where does action potential travel?
From sarcolemma to T-tubules
What do T-tubules connect with?
Sarcoplasmic reticulum
Where is the dihydropyridine receptor?
T-tubules
Where is the C++ channel?
Terminal cisternae
Where is Ca+ released from? Where does it go to?
SR
Sarcoplasm
What triggers a contraction?
Ca+
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