Biol2420 - Nervous System #2: Synapses And Neurotransmitters

Front 1

What is released by the axon terminals in most synapses?

Back 1

A chemical neurotransmitter

Hint 1

Pg. 083

Front 2

What does the chemical neurotransmitter released by the axon terminals in most synapses accomplish?

Back 2

It changes the permeability of the postsynaptic membrane to specific ions causing the postsynaptic cell to become either depolarized or hyperpolarized.

Hint 2

Pg. 083

Front 3

The process of________________can stimulate the production of action potentials.

Back 3

Depolarization

Hint 3

Pg. 083

Front 4

The process of________________ inhibits action potential production by the postsynaptic cell.

Back 4

Hyperpolarization

Hint 4

Pg. 083

Front 5

What is the other cell called that an axon terminal makes a synapse with?

Back 5

Postsynaptic cell

Hint 5

Pg. 083

Front 6

What do the axons of motor neurons make synapses with?

Back 6

Muscle cells or Gland cells

Hint 6

Pg. 083

Front 7

What separates the axon terminal from the postsynaptic cell in the common types of synapses?

Back 7

A Synaptic Cleft or Synaptic Gap

Hint 7

Pg. 083

Front 8

What is opened when action potentials depolarize the plasma membrane of the axon terminal?

Back 8

Voltage-Gated Ca2+ channels

Hint 8

Pg. 083

Front 9

What does Ca2+ stimulate when it is released and can diffuse down its concentration gradient?

Back 9

It stimulates the release of a chemical neurotransmitter

Hint 9

Pg. 083

Front 10

What are chemical neurotransmitter molecules stored in?

Back 10

Synaptic Vesicles

Hint 10

Pg. 083

Front 11

What is the process by which synaptic vesicles are released once they are stimulated by calcium ions?

Back 11

Exocytosis

Hint 11

Pg. 083

Front 12

What are the consequences when there is a greater frequency of action potentials at the axon terminal?

Back 12

More voltage-gated Ca2+ channels will be opened and More synaptic vesicles will undergo exocytosis

Hint 12

Pg. 083

Front 13

What cranial nerve can cause the slowing of the heart rate?

Back 13

The Vagus Nerve

Hint 13

Pg. 083

Front 14

What does a neurotransmitter binds to in the plasma membrane of the postsynaptic cell?

Back 14

Receptor Proteins

Hint 14

Pg. 084

Front 15

What is an important consequence of receptor proteins being found only on the postsynaptic cells?

Back 15

Synapses act like “One-Way Gates” enabling nerve stimulation to travel in only one direction.

Hint 15

Pg. 084

Front 16

What is the result when a neurotransmitter binds to its receptor?

Back 16

Specific Gated Ion channels open

Hint 16

Pg. 084

Front 17

What are the specific gated ion channels known as that open as a result of a neurotransmitter binding to its receptor?

Back 17

Chemically Regulated Channels or
Ligand Regulated Channels

Hint 17

Pg. 084

Front 18

What are Ligands?

Back 18

Ligands are smaller molecules that bind to proteins and are like neurotransmitters.

Hint 18

Pg. 084

Front 19

What is depolarization produced by a neurotransmitter called?

Back 19

Excitatory Postsynaptic Potential (EPSP)

Hint 19

Pg. 084

Front 20

Where must an Excitatory Postsynaptic Potential spread to produce an action potential?

Back 20

It must spread from the dendrites and cell body to the axon hillock.

Hint 20

Pg. 084

Front 21

True or Flase. EPSP in conducted and regenerated like an action potential.

Back 21

False. EPSP is conducted only by cable properties and it decreases in amplitude with increasing distance.

Hint 21

Pg. 084

Front 22

What is hyperpolarization produced by a neurotransmitter called?

Back 22

Inhibitory Postsynaptic Potential (IPSP)

Hint 22

Pg. 084

Front 23

What are the characteristics of Synaptic Potentials?

Back 23

1) They decrease in amplitude with distance
2) They are graded, not all-or-none events
3) They do not have a refractory period and are able to summate

Hint 23

Pg. 084

Front 24

Why do synaptic potentials decrease in amplitude with distance?

Back 24

Because they are not regenerated.

Hint 24

Pg. 084

Front 25

Why are synaptic potentials a graded event?

Back 25

Because they depend on the amount of neurotransmitters molecules released from the synaptic vesicles.
More = a greater depolarization and Fewer = a smaller depolarization

Hint 25

Pg. 084

Front 26

What CNS neurons are able to receive many presynaptic inputs and why?

Back 26

Mulipolar neurons.
Because they contain extensively branched dendritic tress.

Hint 26

Pg. 084

Front 27

What are adding together of Excitatory Postsynaptic Potentials produced in different locations in the postsynaptic neuron called?

Back 27

Spatial Summation

Hint 27

Pg. 085

Front 28

What are IPSPs said to produce and why?

Back 28

Postsynaptic Inhibition Because they can summate in a negative manner with the EPSPs.

Hint 28

Pg. 085

Front 29

What effects can the negative summation of IPSPs with EPSPs produce?

Back 29

1) A decrease in the strength of the depolarization
2) Frequency reduction of action potentials produced by the postsynaptic neurons
3) They can completely inhibit the action potential

Hint 29

Pg. 085

Front 30

True or False. Some neurotransmitter receptors are also ion channels.

Back 30

True. When the neurotransmitter binds to these receptors an ion channel opens in the receptor protein.

Hint 30

Pg. 085

Front 31

True or False. ACh is only an EPSP producing neurotransmitter.

Back 31

False. At some synapses it is excitatory and at others it is inhibitory.

Hint 31

Pg. 085

Front 32

What are the names of the 2 types of ACh receptors?

Back 32

1) Nicotinic ACh receptors
2) Muscarinic ACh receptors

Hint 32

Pg. 086

Front 33

What things can stimulate Nicotinic ACh receptors?

Back 33

ACh
or
Nicotine (from tobacco plants)

Hint 33

Pg. 086

Front 34

What things can stimulate Muscarinic ACh receptors?

Back 34

ACh
or
Muscarine (from a poisonous mushroom)

Hint 34

Pg. 086

Front 35

What type of action do Nicotinic ACh receptors produce?

Back 35

They produce EPSPs

Hint 35

Pg. 086

Front 36

Where are 3 locations that Nicotinic ACh receptors are found?

Back 36

1) Particular brain regions
2) In the postsynaptic membranes of skeletal muscle fiber
3) In postsynaptic membranes of neurons in autonomic ganglia

Hint 36

Pg. 086

Front 37

What does ACh stimulate in the Nicotinic ACh receptors in autonomic ganglia?

Back 37

It stimulates sympathetic and Parasympathetic neurons.

Hint 37

Pg. 086

Front 38

What is a nicotinic ACh receptor protein composed of and when does it open?

Back 38

It is composed of 5 polypeptide chains
It remains closed until 2 ACh molecules bind to it

Hint 38

Pg. 086

Front 39

What happens when 2 ACh molecules bind to Nictotinic ACh receptors?

Back 39

The channel opens and Na + and K+ diffuse at the same time in opposite directions down their concentration gradients.

Hint 39

Pg. 086

Front 40

Why do the ionic movements of Na+ and K+ with regards to their concentration gradients not cancel each other out?

Back 40

Because the sum of the electrical and concentration gradients for Na+ is greater than it is for K+.

Hint 40

Pg. 086

Front 41

What term defines the sum of the electrical and concentration gradients?

Back 41

Electrochemical Gradient

Hint 41

Pg. 086

Front 42

What is a consequence of the Na+ having a greater Electrochemical Gradient compared to that of K+?

Back 42

There is a greater movement of Na+ into the postsynaptic membrane than there is of K+ out of the postsynaptic membrane.

Hint 42

Pg. 086

Front 43

True of False. Nicotinic ACh receptors are both excitatory and inhibitory.

Back 43

False. Nicotinic ACh receptors are always excitatory.

Hint 43

Pg. 086

Front 44

What is the name of the substance that stops the stimulation produced by ACh?

Back 44

Acetylcholinesterase (AChE)

Hint 44

Pg. 086

Front 45

What must be continuously released from the presynaptic axon if stimulation of the postsynaptic membrane is to continue and why?

Back 45

ACh must be continuously released
Because of the presence of the enzyme Acetylcholinesterase

Hint 45

Pg. 086

Front 46

What are GABA receptors and what do they produce?

Back 46

They are ion channels that produce IPSPs

Hint 46

Pg. 086

Front 47

What does GABA stand for?

Back 47

Gamma-amino butyric acid

Hint 47

Pg. 087

Front 48

What ion is the GABA receptor ion channel specifically made for?

Back 48

Cl-

Hint 48

Pg. 087

Front 49

What happens as a result of Cl- diffusing down its concentration gradient into the postsynaptic cell?

Back 49

An IPSP is produced because the postsynaptic membrane becomes hyperpolarized.

Hint 49

Pg. 087

Front 50

Besides inhibition production produced by GABA what other substance is important for control of muscles by the CNS?

Back 50

Glycine

Hint 50

Pg. 087

Front 51

What disorder is a result of having a deficiency of GABA-releasing neurons?

Back 51

Huntington’s Disease

Hint 51

Pg. 087

Front 52

What are often given to people convulsing with muscular spasms?

Back 52

Drugs that promote GABA to open Cl- channels thus promoting inhibition of spinal motor neurons.

Hint 52

Pg. 087

Front 53

What must be utilized with the types of receptors that are not ion channels but spatially separated in the plasma membrane from the chemically gated ion channels they regulate?

Back 53

A “middleman” which are called G-Proteins

Hint 53

Pg. 087

Front 54

Why do G-Proteins have that particular name?

Back 54

Because it refers to their regulation by Guanosine Nucleotides (GDP and GTP).

Hint 54

Pg. 087

Front 55

How many proteins make up G-Proteins?

Back 55

3

Hint 55

Pg. 087

Front 56

What subunits dissociate from the G-Protein-Coupled receptor when a regulatory molecule binds to it?

Back 56

3 subunits dissociate

Hint 56

Pg. 088

Front 57

What are the names of the G-Protein subunits?

Back 57

Alpha, Beta and Gamma

Hint 57

Pg. 088

Front 58

Which of 3 G-protein subunits stay connected together?

Back 58

Beta and Gamma

Hint 58

Pg. 088

Front 59

What happens when either the Alpha or the Beta/Gamma complex moves through the plasma membrane?

Back 59

It joins with an effector molecule (an ion channel for neurotransmitter function)
or
an enzyme

Hint 59

Pg. 088

Front 60

What function can Muscarinic ACh receptors cause?

Back 60

Excitation
or
Inhibition

Hint 60

Pg. 088

Front 61

What is a benefit of having the effector protein separated from the receptor and operated by G-proteins?

Back 61

It allows for greater flexibility

Hint 61

Pg. 088

Front 62

Where are Muscarinic ACh receptors located?

Back 62

In postsynaptic membrane of some neurons in the CNS and In smooth muscles and glands cells innervated by parasympathetic axons.

Hint 62

Pg. 088

Front 63

What kind of effect is produced when ACh binds to muscarinic ACh receptors at synapses where parasympathetic neurons stimulate the smooth muscle of the G.I. tract and the iris of the eye?

Back 63

Excitatory Effect

Hint 63

Pg. 088

Front 64

What kind of effect do the parasympathetic axons in the vagus nerves have on the heart?

Back 64

Inhibitory Effect

Hint 64

Pg. 088

Front 65

Why does inhibition of the heart occur as a result of the parasympathetic axons in the vagus nerve?

Back 65

Because the Beta/Gamma complex that dissociates from the muscarinic ACh receptors cause the gated K+ channels to open allowing for K+ to diffuse out of the cells in the pacemaker region of the heart, thus making the inside of the cells more negative.

Hint 65

Pg. 088

Front 66

What is the general name given to the an important class of regulatory molecules that contains one amino group?

Back 66

Monoamines

Hint 66

Pg. 088

Front 67

What are examples of monoamines?

Back 67

Dopamine
Norepinephrine
Epinephrine
Serotonin

Hint 67

Pg. 088

Front 68

What structure secretes the hormone epinephrine?

Back 68

The Adrenal Medulla Gland

Hint 68

Pg. 088

Front 69

What is Epinephrine also called?

Back 69

Adrenaline

Hint 69

Pg. 088

Front 70

What monoamine functions as both a neurotransmitter and a hormone?

Back 70

Norepinephrine

Hint 70

Pg. 089

Front 71

True or False. Dopamine is only a neurotransmitter.

Back 71

True

Hint 71

Pg. 089

Front 72

What are Dopamine, Norepinephrine and Epinephrine classified as?

Back 72

Catecholamines

Hint 72

Pg. 089

Front 73

What are Catecholamines derived from?

Back 73

The amino acid Tyrosine

Hint 73

Pg. 089

Front 74

True or False. Serotonin is a neurotransmitter.

Back 74

True

Hint 74

Pg. 089

Front 75

True or False. Serotonin is a catecholamine.

Back 75

False. However, it is a monoamine.

Hint 75

Pg. 089

Front 76

Why is Serotonin not classified as a Catecholamine?

Back 76

Because, it is derived from the amino acid Tryptophan and not Tyrosine.

Hint 76

Pg. 089

Front 77

What are the receptors for most monoamine neurotransmitters?

Back 77

G-Protein-Coupled Receptors

Hint 77

Pg. 089

Front 78

What happens once a monoamine binds to its receptor?

Back 78

The alpha subunit dissociates and moves through the plasma membrane.

Hint 78

Pg. 089

Front 79

What is the name of the enzyme that catalyzes the conversion of ATP into a second messenger?

Back 79

Adenylate Cyclase

Hint 79

Pg. 089

Front 80

What is the name of the substance that Adenylate Cyclase converts ATP into?

Back 80

Cyclic AMP
or
cAMP

Hint 80

Pg. 089

Front 81

What indirectly opens ions channels in the postsynaptic cell?

Back 81

Increased production of cAMP.

Hint 81

Pg. 089

Front 82

What is always one constant action of Cyclic AMP?

Back 82

It activates a specific enzyme in the cytoplasm that was previously inactive.

Hint 82

Pg. 089

Front 83

What is the name of the enzyme that Cyclic AMP activates?

Back 83

Protein Kinase

Hint 83

Pg. 089

Front 84

How many steps are there generally in the process of monoamine inactivation?

Back 84

Two-Step Process

Hint 84

Pg. 089

Front 85

What are the two-step processes in the inactivation of monoamine?

Back 85

1) The monoamines in the synaptic cleft are transported back into the presynaptic axons.
2) The monoamines are then broken down by an enzyme located within the presynaptic axon.

Hint 85

Pg. 089

Front 86

What is the name of the enzyme located in the presynaptic axon called?

Back 86

Monoamine Oxidase
or
MA

Hint 86

Pg. 089

Front 87

What are neurons that release dopamine referred to as?

Back 87

Dopaminergic Neurons

Hint 87

Pg. 089

Front 88

What two neural pathways in the brain are formed by dopaminergic neurons?

Back 88

1) Motor Control
2) Motivation and Reward

Hint 88

Pg. 089

Front 89

What does degeneration of dopaminergic neurons in the motor areas of the brain cause?

Back 89

Parkinson’s Disease

Hint 89

Pg. 089

Front 90

What is the most common neurodegenerative disorder?

Back 90

Alzheimer’s Disease

Hint 90

Pg. 089

Front 91

What is the second most common neurodegenerative disorder?

Back 91

Parkinson’s Disease

Hint 91

Pg. 089

Front 92

True or False. Dopamine can cross the blood-brain barrier.

Back 92

False. Dopamine cannot cross the blood-brain barrier.

Hint 92

Pg. 089

Front 93

What are people with Parkinson’s Disease given, since Dopamine cannot cross the blood-brain barrier?

Back 93

L-dopa, the precursor or parent molecule to dopamine.

Hint 93

Pg. 089

Front 94

What are drugs used to treat Schizophrenia called?

Back 94

Narcoleptic drugs

Hint 94

Pg. 089

Front 95

What do Narcoleptic drugs generally do?

Back 95

They antagonize a type of dopamine receptor.

Hint 95

Pg. 089