Lecture 4 - Neuromuscular Communication Flashcards
How do neurons and muscle cells communicate?
Electricity and chemicals
How do neurons use electricity to communicate?
By carrying electrical signals called “action potentials” in neurons and muscle fibers.
How are action potentials created?
By a shift in membrane ions (K+, Na+, Cl-, A-) past threshold level.
What is in the cell membrane produces positive and negative ion concentrations?
Ion channels
What are action potentials?
Shifts in electrical current across the membrane measured as voltage change
What is the function of an action potential?
To serve as a means for information transfer in the neuromuscular system
What is the first phase in an action potential?
Resting (-70 mV)
What is the second phase in an action potential?
Depolarization (positive, increase)
What is the third phase in an action potential?
Repolarization (negative, decrease)
What is the fourth phase in an action potential?
Restoration
What occurs during in a resting membrane?
Ions are stable around -70 mV
What occurs during depolarization?
The ions shift across the membrane inside of the cell to make it more positive until threshold is reached to produce an AP (@ -55 mV)
What occurs during repolarization/hyperpolarization?
Ions shift back toward the resting potential (-70 mV) but overshoot
What happens during restoration?
The membrane slowly returns the to baseline level (-70 mV)
How are signals spread within a neuron?
Starts at dendrite, goes down axon to presynaptic terminal
What are the types of neural networks used to spread signals?
Convergence and divergence
How do convergence networks spread neural signals?
They take signals from many cells going to one or a few cells
How do divergence networks spread neural signals?
They take signals from one or a few cells and go to many cells
APs cannot cross gaps between which places?
Neuron to neuron and muscle cell to neuron aka “synapses”
How do signals get carried across synapses?
Chemically through neurotransmitters
How does neuron to neuron synaptic transmission occur?
Between the presynaptic terminal of one neuron to the dendrite of other neurons
What are gap junctions?
Mechanical connections between neurons, rare
What types of neurotransmitters are typically used in neuron to neuron synaptic transmission?
Dopamine, serotonin, epinephrine, etc.
What do neurotransmitters do?
Change the membrane potential
How does neuron to muscle synaptic transmission occur?
APs are sent down motor neurons to muscle fibers which release neurotransmitters to bind to receptors on muscle membranes resulting in the electrical stimulation of the muscle
What neurotransmitter does neuron to muscle synaptic transmission use?
Acetylcholine
How can neural electricity be measured?
By using an electromyography (EMG)
How does an electromyography work?
By using electrodes to detect electrical activity to measure the magnitude and timing of contraction
What are the components of the cell membrane?
Phospholipids, integral proteins, ligands, ion channels, and cholesterol
