Lecture 4 - Neuromuscular Communication

Question 1

How do neurons and muscle cells communicate?

Answer 1

Electricity and chemicals

Question 2

How do neurons use electricity to communicate?

Answer 2

By carrying electrical signals called “action potentials” in neurons and muscle fibers.

Question 3

How are action potentials created?

Answer 3

By a shift in membrane ions (K+, Na+, Cl-, A-) past threshold level.

Question 4

What is in the cell membrane produces positive and negative ion concentrations?

Answer 4

Ion channels

Question 5

What are action potentials?

Answer 5

Shifts in electrical current across the membrane measured as voltage change

Question 6

What is the function of an action potential?

Answer 6

To serve as a means for information transfer in the neuromuscular system

Question 7

What is the first phase in an action potential?

Answer 7

Resting (-70 mV)

Question 8

What is the second phase in an action potential?

Answer 8

Depolarization (positive, increase)

Question 9

What is the third phase in an action potential?

Answer 9

Repolarization (negative, decrease)

Question 10

What is the fourth phase in an action potential?

Answer 10

Restoration

Question 11

What occurs during in a resting membrane?

Answer 11

Ions are stable around -70 mV

Question 12

What occurs during depolarization?

Answer 12

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)

Question 13

What occurs during repolarization/hyperpolarization?

Answer 13

Ions shift back toward the resting potential (-70 mV) but overshoot

Question 14

What happens during restoration?

Answer 14

The membrane slowly returns the to baseline level (-70 mV)

Question 15

How are signals spread within a neuron?

Answer 15

Starts at dendrite, goes down axon to presynaptic terminal

Question 16

What are the types of neural networks used to spread signals?

Answer 16

Convergence and divergence

Question 17

How do convergence networks spread neural signals?

Answer 17

They take signals from many cells going to one or a few cells

Question 18

How do divergence networks spread neural signals?

Answer 18

They take signals from one or a few cells and go to many cells

Question 19

APs cannot cross gaps between which places?

Answer 19

Neuron to neuron and muscle cell to neuron aka “synapses”

Question 20

How do signals get carried across synapses?

Answer 20

Chemically through neurotransmitters

Question 21

How does neuron to neuron synaptic transmission occur?

Answer 21

Between the presynaptic terminal of one neuron to the dendrite of other neurons

Question 22

What are gap junctions?

Answer 22

Mechanical connections between neurons, rare

Question 23

What types of neurotransmitters are typically used in neuron to neuron synaptic transmission?

Answer 23

Dopamine, serotonin, epinephrine, etc.

Question 24

What do neurotransmitters do?

Answer 24

Change the membrane potential

Question 25

How does neuron to muscle synaptic transmission occur?

Answer 25

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

Question 26

What neurotransmitter does neuron to muscle synaptic transmission use?

Answer 26

Acetylcholine

Question 27

How can neural electricity be measured?

Answer 27

By using an electromyography (EMG)

Question 28

How does an electromyography work?

Answer 28

By using electrodes to detect electrical activity to measure the magnitude and timing of contraction

Question 29

What are the components of the cell membrane?

Answer 29

Phospholipids, integral proteins, ligands, ion channels, and cholesterol