Topic 3: APs, Synapses & NTs

Question 1

When a neuron is not firing it is said to be ____

Answer 1

Resting

Question 2

When a neuron is resting its cell membrane is ____

Answer 2

Polarized

Question 3

A polarized membrane has an electrical gradient (difference) between the _____ of the cell membrane and the _____

Answer 3

Outside, Inside

Question 4

The outside contains more ______ because a ‘pump’ pumps ____ out of the cell

Answer 4

Sodium (Na+), Na+

Question 5

How long does the resting polarized neuron remain polarized ?

Answer 5

Until there is stimulus

Question 6

The Na+ ion channels on the resting neuron’s membrane open suddenly when the stimulus reaches _____ and allow the Na+ that was on the ______ of the membrane to go rushing in

Answer 6

Threshold, outside

Question 7

When the stimulus reaches threshold ___ goes in

Answer 7

Na+ ions

Question 8

What is complete depolarization?

Answer 8

Complete depolarization of the axon results when threshold is reached and the neuron continues to open Na+ channels all along the cells membrane of the axon.

Question 9

Wave depolarization is also called _____

Answer 9

Nerve impulse or the action potential

Question 10

When is the neuron back to its normal polarized state?

Answer 10

After an appropriate amount of Na+ is pumped

Question 11

What is the refractory period?

Answer 11

Refractory period is the time when the neuron is busy returning everything to the normal polarized (resting) state. It usually doesn’t respond to any incoming stimuli.

Question 12

All axons are sheathed in myelin

Answer 12

False.

Many but not all axons are sheathed in myelin

Question 13

The movement of ____ conduct APs along neuron cell membrane

Answer 13

Sodium

Question 14

What is myelin made up of?

Answer 14

Myelin is composed of lipids (fat) and functions like rubber insulation around an electrical wire. It covers the length of the axon except for small nodes about 1mm. apart

Question 15

What is it called when action potentials jump from Node to node ?

Answer 15

Saltatory Conduction

Question 16

The speed of conduction along an axon depends on its ____ and whether it is ______

Answer 16

Diameter, myelinated

Question 17

What is saltatory conduction?

Answer 17

• Saltatory conduction increases nerve conduction velocity w/o having to dramatically increase axon diameter. Without it, conduction velocity would need large increases in axon diameter.
• Saltatory conduction requires much less energy than continuous conduction b/c the sodium ‘pumps’ only need to operate at the nodes of Ranvier and not along the whole axon.

Question 18

Demyelinating diseases such as _____ are often accompanied by debilitating fatigue.

Answer 18

Multiple Sclerosis

Question 19

In _______, the impulse is propagated as a ____________ spreading along the axon

Answer 19

Unmyelinated, continuous wave of depolarization

Question 20

In ______, the impulse ‘jumps’ from node to node, a faster and energy saving process called ________

Answer 20

Myelinated, Saltatory conduction

Question 21

A typical synapse consists of :

Answer 21

1) Presynaptic neuron
2) Synaptic cleft
3) postsynaptic neuron

Question 22

The ____ is where an AP is transmitted from one neuron to another neuron

Answer 22

Synapse

Question 23

There are synapses between _____ and ____ and between ______ and ______

Answer 23

Neurons and muscles (NMJ), neurons and glands

Question 24

A ______ is a chemical released by a presynaptic neuron

Answer 24

Neurotransmitter. It diffuses across the synaptic cleft to stimulate or inhibit the postsynaptic neuron.

Question 25

Name the types of synapses:

Answer 25

Axon terminals can connect with : 1) dendrites of another neuron: axodendritic synapse (most common) 2) the cell body of another neuron: axiomatic synapse 3) the axon of another neuron: axoanonal synapse

Question 26

When an AP reaches presynaptic terminal, vesicles containing neurotransmitters (NT) fuse with the neuron's membrane and release their contents into the _______

Answer 26

synaptic cleft

Question 27

______ are required for the fusion to take place

Answer 27

Calcium ions

Question 28

An EPSP makes it _____ likely that an AP will continue in the postsynaptic neuron.

Answer 28

More likely. | Threshold of the postsynaptic neuron will most likely be reached

Question 29

An IPSP makes it ____ likely that an action potential will continue on in the post synaptic neuron

Answer 29

less likely. | Poles are further apart

Question 30

Frequent postsynaptic potentials at the same synapse occur in rapid succession. The effect of the first potential does not have time to dissipate and the succeeding potentials add to the previous ones

Answer 30

Temporal summation E.g. Mom, mom, mommy .. what?

Question 31

Multiple excitatory signals to various postsynaptic sites

Answer 31

Spatial summation

Question 32

What is the All or None Law?

Answer 32

If the sum of all EPSPs and IPSPsr reaches threshold, an AP will result. however, if the neuron does not reach threshold, an AP will not occur. If it fires and the AP goes all the way to the end of the axon it is called All or None Law

Question 33

The change in the frequency of action potentials usually indicates ________

Answer 33

A change in the intensity of a stimulus

Question 34

A chemical that is released from the a neuron and transmits a nerve impulse from one neuron to another, muscle or organ or other tissue.

Answer 34

Neurotransmitter

Question 35

A NT ______ is a chemical that has the same effect on the postsynaptic neuron as the neurotransmitter does

Answer 35

agonist

Question 36

An ______ is a molecule that blocks the effect of a NT or its agonists

Answer 36

Antagonist

Question 37

Life-threatening depression of respiratory system is a side effect of _____

Answer 37

opioid overdose.

Question 38

When administered it allows an overdose victim to breathe normally

Answer 38

Naloxone, aka Narcan | e.x Often taken by musicians

Question 39

What is the most common inhibitory Neurotransmitter in the CNS

Answer 39

GABA - Gamma-aminobutyric acid

Question 40

Nerve cells fire often without this

Answer 40

GABA

Question 41

Low GABA activity is related to

Answer 41

Anxiety disorders, such as panic attacks, seizure disorders and cognitive impairment

Question 42

Supplement sold and promoted as a natural tranquilizer is ___

Answer 42

Valerian. | GABA taken as a supplement does not cross the BBB and works as a placebo.

Question 43

Examples of benzodiazepines are

Answer 43

Vallium and Librium

Question 44

Glutamate is the most common inhibitory neurotransmitter in the CNS

Answer 44

False. It is an excitatory NT

Question 45

This is involved in cognition, memory and learning

Answer 45

Glutamate

Question 46

Due to chronic inflammation, microglia can become ___

Answer 46

over activated (sensitized)

Question 47

____ use glutamate to destroy infected neurons, virus, and bacteria, but this can also cause large amounts of collateral damage to healthy neurons

Answer 47

Microglia (phagocytes of the CNS)

Question 48

Over activated microglia can result in a self-perpetuating cycle called ______

Answer 48

Reactive microgliosis . An underlying mechanism of progressive neuron damage across numerous neurodegenerative diseases, regardless of the instigating stimuli. E.g. NFL players experience this due to concussions

Question 49

____ deficit is linked to depression

Answer 49

Serotonin.

Question 50

a class of drugs that alleviate depression by increasing the length of time that serotonin stays in the synapse.

Answer 50

Selective Serotonin re-uptake inhibitors (SSRI) Makes it more likely to bind to postsynaptic receptors.

Question 51

One well-known SSRI is _____

Answer 51

Prozac.

Question 52

An excess of dopamine in the limbic system and not enough in the cortex has been linked to ______

Answer 52

Paranoia and addiction (this is why addiction is a disease)

Question 53

An excess of dopamine in the frontal lobe _____

Answer 53

relieves pain and boosts feelings of pleasure

Question 54

Memory problems, Mov't problems such as parkinson's are a cause of _____

Answer 54

Shortage of dopamine

Question 55

Dopamine agonist drugs are linked to _____

Answer 55

Pathologic gambling, compulsive shopping, her impulse control disorders

Question 56

____ is secreted from the hypophysis. It is a hormone that also acts as a neurotransmitter in the brain

Answer 56

Oxytocin

Question 57

Oxytocin is thought to be released during ____

Answer 57

Hugging, touching and orgasm in both sexes.

Question 58

Two ways in which drugs modify synapse function

Answer 58

1. Mimic the neurotransmitter (agonist) e. g morphine mimics endorphins in pain pathways 2. Block re-uptake of neurotransmitter (antagonist) - Cocaine blocks the reuptake of dopamine - Prozac is a serotonin reuptake inhibitor 3. Block enzyme pathways that degrade neurotransmitters - several anti-depressants block an enzyme that degrades serotonin, dopamine, epinephrine, and norepinephrine

Question 59

"PANS" | The neurotransmitter released at the postganglionic synapses is _________

Answer 59

Acetylcholine (Ach)

Question 60

Axons that release ACh are called ______

Answer 60

Cholinergic fibres

Question 61

Aka for cholinergic drugs

Answer 61

Parasympathomimetic drugs : because they produce effects that imitate parasympathetic nerve stimulation

Question 62

"SYNS" | The neurotransmitter released at the postganglionic synapses is _________

Answer 62

Norepinephrine aka noradrenalin

Question 63

Fibres that release norepinephrine are called _____

Answer 63

adrenergic fibres

Question 64

aka for adrenergic fibres

Answer 64

Sympathomimetic drugs: because they mimic effects similar to those produced by the sympathetic nervous system

Question 65

_____ drugs increase BP and HR and are useful in treating systemic trauma, including shock, and cardiac arrest

Answer 65

Adrenergic drugs

Question 66

Drugs that block or inhibit the release activity of NE known as

Answer 66

adrenergic blocking agents

Question 67

Aka for beta-adrenergic blocking agent

Answer 67

Beta-blocker : reduces symptoms connected with HT, cardiac arrhythmias and angina pectoris

Question 68

Why must people who take beta-blockers avoid caffeine, alcohol, and salty foods?

Answer 68

because the interaction of those substances and the drug can raise the heart rate and blood pressure