2.4: Neural Firing

Question 1

Neurons

Answer 1

Our body’s nerve cells which make up the nervous system.

Question 2

How Does a Neuron Fire?

Answer 2

For a neuron to fire, or communicate with another neuron, information must first be gathered in by the dendrites of the receiving neuron. From there, the information passes through the cell body to the axon.

Question 3

Dendrite

Answer 3

Receives information and transfers it to the cell body.

Question 4

Cell Body/Soma

Answer 4

The neuron’s support center.

Question 5

Axon

Answer 5

Passes messages to its terminal branches.

The neural impulse goes through the axon and is an electrical signal.

Question 6

Myelin Sheath

Answer 6

A layer of tissue that covers the axon and speeds up neural impulses.

Without a myelin sheath, there is a loss of muscle control.

Question 7

Terminal Branches

Answer 7

Pass on chemical messages to other cells and parts of the body.

Question 8

Action potential

Answer 8

Must occur for the message to continue to travel down the axon.

Question 9

Threshold Being Met

Answer 9

Meaning it has received enough stimulation from the original sending neuron.

Question 10

What Would Happen If The Threshold is Met?

Answer 10

If this threshold is met, the action potential occurs and the message travels down the axon via a process of depolarization.

Question 11

Depolarization

Answer 11

The process that carries the neural impulse through the axon, action potential is what must happen for the process to occur.

Question 12

What Would Happen If The Threshold is Not Met?

Answer 12

If the threshold is not met, nothing happens.

Question 13

All-Or-None Response

Answer 13

Neurons either fire, or they don’t.

Question 14

Two Types of Signals/Neurotransmitters

Answer 14

Excitatory Signals/Neurotransmitters & Inhibitory Signals/Neurotransmitters.

Question 15

Excitatory Signals/Neurotransmitters

Answer 15

Pushes neuron’s “accelerator”; makes a neuron more likely to reach action potential and fire.

Question 16

Inhibitory Signals/Neurotransmitters

Answer 16

Pushes a neuron’s “brake”; makes it less likely for a neuron to reach action potential.

Question 17

What does Terminal Branches Contain?

Answer 17

The terminal branches of a neuron contain neurotransmitters which are then released.

These neurotransmitters cross the synaptic gaps between neurons and are gathered in by dendrites of a new neuron, continuing the communication process.

Question 18

Synapse

Answer 18

Where two neurons meet and neurotransmitters are released into it.

Question 19

Types of Synapses

Answer 19

Electrical & Chemical Synapses.

Question 20

Electrical Synapse

Answer 20

Relays quick messages to another cell.

Question 21

Chemical Synapse

Answer 21

Sends messages slowly to another cell.

Question 22

Where are Neurotransmitters Stored in?

Answer 22

Neurotransmitters are stored in vesicles in the axon terminal.

Question 23

What Happens When There is a Neural Impulse?

Answer 23

When there is a neural impulse, the vesicle binds with the edge of the axon terminal and the neurotransmitters are released into the synaptic cleft.

Question 24

What Happens When There is a Neural Impulse?

Answer 24

When there is a neural impulse, the vesicle binds with the edge of the axon terminal and the neurotransmitters are released into the synaptic cleft.

Question 24

What Happens When There is a Neural Impulse?

Answer 24

When there is a neural impulse, the vesicle binds with the edge of the axon terminal and the neurotransmitters are released into the synaptic cleft.

Question 25

Reuptake

Answer 25

A process in which the neurotransmitters are absorbed back into the original neuron, if they do not find a home on the dendrites of another neuron.

Question 26

Neurotransmitters

Answer 26

Act as agonists or antagonists in our body.

Question 27

Antagonist Neurotransmitter

Answer 27

Binds to the dendrites of a neuron and prevents or blocks its response.

Question 28

Agonists

Answer 28

Bind to receptor sites and mimic the effects of a specific neurotransmitter.

Opiates are an example of an agonist as they mimic the effects of endorphins in our body (which is why they produce a morphine-like effect).

Question 29

Acetylcholine (ACh)

Answer 29

Function: Enables muscle action, learning, and memory.

Examples of Malfunctions: With Alzheimer’s disease, ACh-producing neurons deteriorate.

Question 30

Dopamine

Answer 30

Function: Influences movement, learning, attention, and emotion.

Examples of Malfunctions: Oversupply –> schizophrenia Undersupply –> tremors and decreased mobility in Parkinson’s disease.

Question 31

Serotonin

Answer 31

Function: Affects mood, hunger, sleep, and arousal.

Examples of Malfunctions: Undersupply –> depression. Antidepressant drugs raise serotonin levels.

Question 32

Norepinephrine

Answer 32

Function: Helps control alertness and arousal.

Examples of Malfunctions: Undersupply can depress mood.

Question 33

GABA

Answer 33

Function: A major inhibitory neurotransmitter.

Examples of Malfunctions: Undersupply –> seizures, tremors, and insomnia.

Question 34

Glutamate

Answer 34

Function: A major excitatory neurotransmitter; involved in memory.

Examples of Malfunctions:
Oversupply –> over stimulates the brain –> migraines and seizures (why lots of people avoid MSG in their food).

Question 35

Endorphins

Answer 35

Function: Diminishes the perception of pain and acts as a natural sedative.

Examples of Malfunctions: Undersupply –> can cause depression, anxiety and moodiness.

Question 36

What Happens After Firing?

Answer 36

After a neuron fires and reaches action potential, it goes into its refractory period, where it cannot fire.

Question 37

Refractory Period

Answer 37

This period of rest prevents one signal from combining with another.