Neurochemistry: Chemical Signaling

Question 1

Loewi’s frog heart

Answer 1

Stimulated vagus nerve, slowed down heartbeat

Transferred surrounding liquid from heart #1 to second heart

Observed some reduction with second heart that had only liquid, no chemical stimulation

ACh is the neurotransmitter involved

Question 2

Receptors act like ________

Neurotransmitters act like _________

Answer 2

Locks

Keys

Question 3

Ligand

Answer 3

“Generic key”

Any substance that binds to a receptor

Question 4

Endogenous

Answer 4

Produced in the body

Question 5

Exogenous

Answer 5

Not produced in the body

Question 6

Agonist

Answer 6

Activates receptor

Question 7

Antagonist

Answer 7

Blocks the receptor

Reducing it’s normal actions

Question 8

Ionotropic receptors

Answer 8

Neurotransmitter binds

Receptor changes shape

Ionchannel opens or closes

Fast acting

Question 9

Inhibitory binding causes ______

Excitatory binding causes ________

Answer 9

Hyperpolarization

Depolarization (creates AP)

Question 10

Metabotropic receptors

Answer 10

Don’t open/close themselves (NO ION CHANNELS)

Neurotransmitter binds

Activate second messengers (which open/close ion channels and can change gene expression)

Slower acting

Question 11

Neurotransmitters

Answer 11

Synthesized in presynaptic cell, stored in axon terminal

Released when APs reach terminal

Recognized by postsynaptic receptor

Cause changes in postsynaptic cell

Blocking neurotransmitters interferes with their effects

Question 12

Amines

Answer 12

Acetylcholine (ACh), Norepinephrine (NE), epinephrine (adrenaline), serotonin (5-HT), dopamine (DA)

Question 13

Amino acids

Answer 13

GABA (inhibitory), Glutamate (excitatory)

Question 14

Neuropeptides

Answer 14

Opioid peptides: enkephalins, endorphins

Peptide hormones: oxytocin, vasopressin

Question 15

Gas

Answer 15

Nitric oxide, carbon monoxide

Question 16

Types of neurotransmitters

Answer 16

Amines

Amino acids

Neuropeptides

Gas

Question 17

Acetylcholine (ACh)

Answer 17

PNS- found at all neuromuscular joints, (controls basic movement)

Cholinergic pathways- basal forebrain, hippocampus, amygdala (controls attention, arousal, reward processing, learning and memory)

Question 18

Norepinephrine (NE)

Noradrenaline

Answer 18

PNS- in autonomic ganglia (sympathetic), (controls fight or flight)

Noradrenergic pathways- cortex, limbic system, thalamus, (controls attention, arousal, mood, sex)

Question 19

Serotonin (5-HT)

Answer 19

Serotonergic pathways- throughout the CNS, (controls mood, anxiety, sleep, attention)

Serotonergic receptors- many subtypes (18), targets of psychotropic drugs

Question 20

Dopamine (DA)

Answer 20

Dopamenergic pathways-

• mesostriatal: substantia Nigra to basal ganglia (voluntary movement)
• mesolimbocortical: especially important for reward, limbic (learning and memory), cortex (attention, problem solving, motivation, reward)
• associated with Parkinson’s

Question 21

Ventral Tegmental Area (VTA)

Answer 21

Projects dopaminergic fibers to the nucleus accumbens

Question 22

Reuptake

Answer 22

Neurotransmitter molecules are brought back into the presynaptic terminal

Relies on special proteins called transporters

Question 23

Gas neurotransmitters

Answer 23

Produced outside axon terminals and diffuses out of the neuron as it is produced

No receptors in the membrane of the target cell are involved

Can function as retrograde transmitters