Chapter 5: How Neurons Communicate and Adapt

Question 1

What does Acetylcholine (ACh) do?

Answer 1

activates skeletal muscles in the SNS; may either excite or inhibit internal organs in the NAS; also the first neurotransmitter discovered

Question 2

What does Epinephrine do?

Answer 2

it is a chemical messenger that acts as a neurotransmitter in the CNS and as a hormone to mobilize the body for fight or flight during times of stress

Question 3

What does Norepinephrine do and where is it found?

Answer 3

it accelerates heart rate in mammals; found in the brain and sympathetic division of the ANS

Question 4

What is a Neurotransmitter?

Answer 4

it is a chemical with an excitatory or inhibitory effect when it is released by a neuron on a target

Question 5

What does Dopamine do and what class of NT is it?

Answer 5

it is involved in coordinating movement, attention, learning and reinforcing behaviors; it is an Amine NT

Question 6

What happens in the brain if you have Parkinsons?

Answer 6

there is a substantia nigra dysfunction involved with dopamine loss in the substantia nigra

Question 7

What is a Synaptic Vesicle?

Answer 7

a membranous compartment that encloses neurotransmitters

Question 8

What is a Synaptic Cleft?

Answer 8

a gap between the presynaptic and post-synaptic membranes

Question 9

What is a Chemical synapse?

Answer 9

the junction at which messenger molecules are released when stimulated by an action potential

Question 10

What are Storage Granules?

Answer 10

compartments in the neuron that hold several vesicles containing a specific neurotransmitter

Question 11

What is a gap junction and what process are they relevant in?

Answer 11

it is an area of contact between adjacent cells in which ion channels form a pore that allows ions to pass directly from one cell to the next; it is relevant in electrical synapses because that is when the neurons come in to contact

Question 12

What are the 4 steps of neurotransmission?

Answer 12

1) Neurotransmitter synthesis and storage
2) Neurotransmitter release
3) Receptor-site activation
4) Neurotransmitter deactivation

Question 13

What are the 2 ways neurotransmitters are derived?

Answer 13

1) Synthesized in cell body from instructions in DNA and transported to axon terminal
2) Synthesized in axon terminal from building blocks derived from food

Question 14

What is a transporter molecule and what role does it play in the 2nd way NTs are derived?

Answer 14

it is a protein molecule that pumps substances across the membrane; it absorbs precursor chemicals from the blood used in this NT synthesis process

Question 15

What happens during neurotransmitter release?

Answer 15

an action potential changes the voltage of the presynaptic cell and causes an influx of Ca2+; these Ca2+ ions cause the vesicles to fuse with the membrane and get released by exocytosis

Question 16

What are transmitter-activated receptors and what 3 things can happen to them when something binds to them?

Answer 16

protein that has specific neurotransmitter binding site and is embedded in the membrane of the cell; 1) Depolarized 2) Hyperpolarized 3) other chemical reactions that modulate excitatory/inhibitory happenings

Question 17

What are autoreceptors and what do they affect?

Answer 17

they respond to the same transmitter released by the neuron and may affect that presynaptic neuron

Question 18

What is a quantum?

Answer 18

a vesicle worth of NTs that is the minimum required for any change

Question 19

What are the 4 ways the neurotransmitters can become deactivated?

Answer 19

1) Diffusion: some of the NT simply diffuse away
2) Degradation: enzymes in the cleft break down NT
3) Reuptake: transporters bring them back in as well as broken NT
4) Astrocyte uptake: can be taken up by neighbouring astrocytes

Question 20

What are some different varieties of synapses?

Answer 20

Axomuscular, axodendritic, axosomatic, axoaxonic, axosynaptic (another synapse), axoextracellular (outside cell), axosecretory (into blood vessel), dendrodenritic (dendrite to dendrite)

Question 21

What are some qualities of excitatory vs inhibitory synapses?

Answer 21

Excitatory: round vesicles, wider cleft, active areas are larger

Question 22

What parts of the cell are typically excitatory and what are inhibitory?

Answer 22

cell body inhibitory and dendritic tree excitatory; cell body kind of stops it if it isn’t enough to overcome it

Question 23

What are the 4 criteria for identifying NTs?

Answer 23

1) must be synthesized in neuron or present in it
2) when neuron is active, chemical must be released and produce a response in target
3) same response when chemical is experimentally placed on target
4) mechanism must exist to remove chemical once it is done

Question 24

What NT do all motor neurons leaving the SC use?

Answer 24

ACh (acetylcholine)

Question 25

What is a Renshaw loop?

Answer 25

axon goes to muscle and to interneuron which can be inhibitory to prevent the overexcitation of the neuron

Question 26

What is a small molecule transmitter and what are examples of them?

Answer 26

quick acting NT that is synthesized in the axon terminal from products derived from diet; Histamine (sleep and wake, can cause constriction of smooth muscles), Acetylcholine

Question 27

What is acetylcholine synthesized from?

Answer 27

choline and acetate

Question 28

What are the 3 main Amine’s and how are they synthesized?

Answer 28

dopamine, norepinephrine, epinephrine; go from tyrosine to L-Dopa to Dopamine to Norepinephrine to Epinephrine; they all can be only produced in limited quantities

Question 29

What affects does Serotonin have on the brain/body?

Answer 29

mood, aggression, appetite, pain and arousal

Question 30

What are the 2 main amino acids, how do they differ and what do they do?

Answer 30

Glutamate: excites neurons
Gaba: inhibits neurons, same as glutamate but without carboxyl

Question 31

What is a neuropeptide? What does it do? Where is it made? What are examples?

Answer 31

a short amino acid chain; acts as a NT but a slow acting oneand as a hormone and may contribute to learning, does not affect post synaptic voltage, affects indirectly the structure and function; it is made in the ribosomes; opium and morphine

Question 32

What is the most common lipid transmitter and what does it do?

Answer 32

endocannabinoid; synthesized in postsynaptic to act on presynaptic; affects appetite, pain, sleep, mood, and stress respone; almost like post synaptic controls presynaptic

Question 33

What are 3 examples of Gaseous Transmitters and what do they do?

Answer 33

1) Nitric oxide: dilate blood vessels, aids digestion and cellular metabolism (in viagra)
2) Carbon monoxide: activates cellular metabolism
3) Hydrogen Sulfide: slows cellular metabolism
They diffuse across the cell membrane and immediately become active

Question 34

What is an Ionotropic receptor and how does it function?

Answer 34

an embedded membrane protein; acts as a 1) binding site of NT 2) pore that regulates ion flow; basically allows ions to move across membrane

Question 35

What is a metabotropic receptor and how does it function

Answer 35

an embedded membrane protein; has a binding site for a NT linked to a G protein; it can affect other receptors or act with 2nd messengers to affect other cellular processes including opening a pore (doesn’t do it directly though); can activate an “amplification cascade”

Question 36

What is a G protein and what are its subunits?

Answer 36

a Guanyl nucleotide binding protein, when activated it binds to other proteins; Alpha, Beta and Gamma

Question 37

What are 2 things the alpha sub unit of the G protein does?

Answer 37

1) Binds to channels to allow ion flow

2) bind to enzyme which activates the second messenger

Question 38

What is a second messenger and what does it do?

Answer 38

it initiates a biochemical process when activated by a NT; it can cause a channel to change structure, form new channels or bind to DNA to initiate or cease production of proteins

Question 39

What is a Cholinergic neuron and what is it’s main receptor?

Answer 39

a neuron that us ACh as its main NT (motor neurons); its main receptor is nAChr (nicotinic acetylcholine receptor) which is ionotropic

Question 40

What NT do the sympathetic and parasympathetic systems use the most of?

Answer 40

Sympa: norepinephrine
Parasympa: acetylcholine

Question 41

What is an activating system?

Answer 41

a neural pathway that coordinates brain activity through a single NT, cell bodies are in the brainstem nucleus and it goes throughout a wide CNS region

Question 42

What is a habituation response in neurons and what is the neural basis of one?

Answer 42

a learned behavior in which response to a stimulus weakens with repeated presentations; reduced sensitivity of Ca2+ channels underlies habituation, there is less of an influx of Ca2+

Question 43

What is a sensitization response in neurons and what is the neural basis of one?

Answer 43

it is a response that strengthens with repeated presentations; less responsive potassium channels underlie sensitization, repolarization does not happen as quickly

Question 44

What neurotransmitter is crucial to learning?

Answer 44

cAMP, but it must be in the right amounts