Transmission
Neural
By: Mollee Lamm
Action Potential Initiation
Click Here
Action Potential Propagation
Neurotransmitter Release
Muscle Fiber Activation
Excitation-Contraction Coupling
Initiation
Action potential initiation happens at the axon hillock of the the motor neuron. When the stimulus hits the threshold level, voltage gated sodium channels open which allows for Na+ ions to go into the neuron which causes depolarization. This depolarization causes more voltage gates Na+ channels to open which causes the generation of an action potential. This action potential goes down the axon of the motor neuron to the neuromuscular junction.
Propagation
As the action potential goes down the axon and is produced because of voltage gated ion channels. Voltage gated Na+ channels open all along the axon which allows for the action potential to be produced quickly to the axon terminal. Once it reaches that axon terminal the next stage occurs.
Neurotransmitter Release
Neurotransmitters are released at the Neuromuscular Junction due to action potentials being generated at the opening of voltage gated Ca2+ channels in the presynaptic membrane. These Ca2+ ions that go in the axon terminal lead to the fusion of synaptic vesicles which have acetylcholine in them, with the presynaptic membrane. Acetylcholine is released into the synaptic cleft due to exocytosis and diffuse along the cleft to the motor end plate of the muscle fiber.
Muscle Fiber Activation
ACh will bind with nAChRs on the motor end plare of the muscle fiber which causes depolarization to occur.This causes the Na+ voltage gated channels to open which allows them in the muscle fiber to start an action potential. This action will travel along the fiber and into the transverse tubules causing excitation-contraction coupling.
Excitation-Contraction Coupling
The action potential that goes into the muscle fibers from the T-tubules which causes Ca2+ to be released from the sarcoplasmic reticulum and into the cytoplasm. Ca2+ binds to troponin on the thin filaments which causes the active sites on the actin to be exposed. The myosin head binds to the active sites exposed making a cross bridge. ATP hydrolysis makes the myosin heads move which causes the actin filaments to slide past the myosin filaments therefore leading to a muscle contraction.
Neural Transmission
Mollee Lamm
Created on March 27, 2024
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Transcript
Transmission
Neural
By: Mollee Lamm
Action Potential Initiation
Click Here
Action Potential Propagation
Neurotransmitter Release
Muscle Fiber Activation
Excitation-Contraction Coupling
Initiation
Action potential initiation happens at the axon hillock of the the motor neuron. When the stimulus hits the threshold level, voltage gated sodium channels open which allows for Na+ ions to go into the neuron which causes depolarization. This depolarization causes more voltage gates Na+ channels to open which causes the generation of an action potential. This action potential goes down the axon of the motor neuron to the neuromuscular junction.
Propagation
As the action potential goes down the axon and is produced because of voltage gated ion channels. Voltage gated Na+ channels open all along the axon which allows for the action potential to be produced quickly to the axon terminal. Once it reaches that axon terminal the next stage occurs.
Neurotransmitter Release
Neurotransmitters are released at the Neuromuscular Junction due to action potentials being generated at the opening of voltage gated Ca2+ channels in the presynaptic membrane. These Ca2+ ions that go in the axon terminal lead to the fusion of synaptic vesicles which have acetylcholine in them, with the presynaptic membrane. Acetylcholine is released into the synaptic cleft due to exocytosis and diffuse along the cleft to the motor end plate of the muscle fiber.
Muscle Fiber Activation
ACh will bind with nAChRs on the motor end plare of the muscle fiber which causes depolarization to occur.This causes the Na+ voltage gated channels to open which allows them in the muscle fiber to start an action potential. This action will travel along the fiber and into the transverse tubules causing excitation-contraction coupling.
Excitation-Contraction Coupling
The action potential that goes into the muscle fibers from the T-tubules which causes Ca2+ to be released from the sarcoplasmic reticulum and into the cytoplasm. Ca2+ binds to troponin on the thin filaments which causes the active sites on the actin to be exposed. The myosin head binds to the active sites exposed making a cross bridge. ATP hydrolysis makes the myosin heads move which causes the actin filaments to slide past the myosin filaments therefore leading to a muscle contraction.