Chapter 5: How do Neurons Communicate and Adapt?

Question 1

Structure of synapses

Answer 1

Presynaptic membrane (axon terminal)

Postsynaptic membrane (dendritic spine)

Synaptic cleft (space between)

Tripartite synapse

Synaptic vesicle (presynaptic)

Storage granule

Postsynaptic receptor

Anterograde synaptic transmission

Transporter

Question 2

Steps of neurotransmission

Answer 2

1. Neurotransmitter is synthesized somewhere inside the neuron
2. Packaged and stored within vesicles at the axon terminal
3. Transported to presynaptic membrane and released into cleft in response to an action potential
4. Vesicles Bind and activate receptors on the postsynaptic membrane
5. Degraded or removed so it will not continue to interact with a receptor and work indefinitely

Question 3

Ca2+ Ions

Answer 3

Positively charged calcium ions enters the terminal and binds to the protein calmodulin forming a complex

The complex causes some vesicles to empty their contents into the synapse and others to get ready to empty their contents

Question 4

Transporters

Answer 4

Protein molecule that pumps substances across a membrane, energy dependent

Question 5

Gap junctions

Answer 5

Fused presynaptic and postsynaptic membrane that allows an action potential to pass directly from one neuron to the next

Question 6

Connexin

Answer 6

gap junction proteins, are structurally related transmembrane proteins that assemble to form vertebrate gap junctions

Question 7

How to identify a neurotransmitter?

Answer 7

1. Has to be present in the neuron
2. When the neuron is active, the chemical must be released and produce a response in some target (do something after release)
3. The same response must be obtained when the transmitter is experimentally placed on the target (same molecule)
4. A mechanism must exist for removing the transmitter from this site of action after its work is done

Question 8

Classes of neurotransmitters

Answer 8

Small-molecule transmitters, Peptide transmitters, Lipid transmitters, Gaseous and Ion transmitters

Question 9

Acetylcholine synthesis

Answer 9

• Acetylcholinetransferase , joins the choline to the acetate
• Breakdown of acetylcholine by acetylcholinesterase (AChE) into choline and acetate, regulates
• Acetylcholinesterase can be blocked to increase ACh in the synapse, helps with alzheimers

Question 10

Classes of receptors

Answer 10

Ionotropic and metabotropic receptor

Question 11

Receptor subtypes

Answer 11

Ionotropic receptors (first)
Metabotropic receptors (second)

Acetylcholine (ACh)
Nicotinic
5 muscarinic*

Dopamine (DA)
N/A
5 dopamine

GABA
GABAA
GABAB

Glutamate (Glu)
NMDA, AMPA, kainate
7 mGluRs, NMDA

Glycine (Gly)
Glycine, NMDA
N/A

Histamine (H)
N/A
3 histamine

Norepinephrine (NE)
N/A
8 NE alpha and 3 NE beta

Serotonin (5-HT)
1 5-HT3
13 5-HT

Question 12

5-HT3

Answer 12

serotonin receptor

Question 13

N-methyl-D-aspartate

Answer 13

Glutamate receptor (ionotropic and metabotropic)

Question 14

Activating systems in central nervous system

Answer 14

Both sym. and parasym. Are controlled by the acetylcholine neurons that emanate from the CNS at two levels of the spinal cord

Question 15

Cholinergic

Answer 15

• acetylcholine
• Normal waking behavior
• function in attention and memory
• Loss of cholinergic neurons is associated with alzheimers disease

Question 16

Dopaminergic

Answer 16

Dopamine

Nigrostriatal pathways
- Active in maintaining normal motor behavior
- Loss of Da is related to muscle rigidity and dyskinesia in parkinson disease

Mesolimbic pathways
- Dopamine release causes repetition of behaviors
- Thought to be the neurotransmitter system most affected by addictive drugs and behavioral addictions
- Increases in DA activity may be related to schizophrenia
- Decreases in DA activity may be related to deficits of attention

Question 17

Noradrenergic

Answer 17

• norepinephrine
• Plays a role in learning by stimulating neurons to change structure, may also facilitate normal development of the brain and organize movements
• Imbalances associated with depression, mania

Question 18

Serotonergic

Answer 18

• Serotonin
• Often found outside the brain
• Plays a role in wakefulness and learning
• Imbalances associated with depression, schizophrenia, OCD, sleep apnea, infant death syndrome