Chemistry of Behavior

Question 1

if the overall stimulation reaches or exceeds the threshold of activation at the axon hillock, an action potential is produced in the…

Answer 1

postsynaptic cell

Question 2

is the summing of the potentials that reach the axon hillock from different locations across the neuron

Answer 2

Spatial Summation

Question 3

is the summing of all the potentials that reach the axon hillock based on time of arrival

Answer 3

Temporal Summation

Question 4

The closer together in time the potentials arrive, the greater their impact and likelihood of producing an action potential because…

Answer 4

they can build on one another

Question 5

1. Decremental
2. Super Fast
3. Passive (energy is not used)

Answer 5

EPSPs/IPSPs

Question 6

• Non-decremental
• Conducted more slowly than PSPs
• Passive and Active (use ATP)

Answer 6

Action Potentials

Question 7

Action potentials reach the axon terminal – the presynaptic side of a synapse

• Action potentials cause vesicles to release neurotransmitters into the synaptic cleft
  Molecules bind to neurotransmitter receptors in the membrane of the postsynaptic cell, where they cause small changes in membrane potential (postsynaptic potentials)
• Neurotransmitters are either broken down by enzymes, diffuse out the synaptic cleft, or are brought back in the presynaptic terminal via reuptake, which relies on special transporters

Answer 7

Synaptic Transmission is a Complex Electrochemical Process

Question 8

are very selective (think: lock and key) and respond to certain neurotransmitters (or their mimics, like a drug that is similarly shaped)

• can be categorized into one of the following two groups: ionotropic and metabotropic

Answer 8

Neurotransmitter receptors

Question 9

quickly change shape and open an ion channel when the transmitter molecule binds, allowing in specific ions

• This changes the local membrane potential
• If the change is depolarization, we call it an excitatory synapse
• If the change is hyperpolarization, we call it an inhibitory synapse

Answer 9

Ionotropic Receptors

Question 10

alter chemical reactions in the cell

• They use a system of second messengers (G protein) to alter reactions within the cell
• This may open nearby ion channels to the change the excitability of the cell, or it may start chemical reactions to alter gene expression to make various proteins

Answer 10

Metabotropic Receptors

Question 11

1. It’s synthesized in presynaptic neuron and stored in axon terminals
2. It’s released when action potentials reach axon terminals
3. It’s recognized by receptors on the postsynaptic membrane
4. It causes changes in postsynaptic cell
5. Blocking its release interferes with a cell’s ability to affect a postsynaptic cell

Answer 11

Criteria for Neurotransmitters Classification

Question 12

GABA, glutamate

Answer 12

Amino Acid Neurotransmitters

Question 13

oxytocin, vasopressin

Answer 13

Peptide Neurotransmitters (neuropeptides)

Question 14

acetylcholine, dopamine, serotonin

Answer 14

Amine Neurotransmitters

Question 15

nitric oxide, carbon monoxide

Answer 15

Gas Neurotransmitters

Question 16

The Most Common Transmitters in the Brain are Amino Acids! (remember)

Question 17

most widespread excitatory transmitter

• Makes a neuron more likely to fire an action potential
• AMPA and NMDA receptors (both ionotropic)

Answer 17

Glutamate

Question 18

most widespread inhibitory transmitter

• Makes a neuron less likely to fire by allowing negative ions (e.g., Cl-) into cell
• GABA receptors are ionotropic AND metabotropic
• Benzodiazepines (Valium, Ativan) mimic GABA and are used to relax muscles, induce sleep, and reduce anxiety

Answer 18

Gamma-Aminobutyric Acid (GABA)

Question 19

1. It’s produced outside axon terminals – mainly in dendrites – and diffuses out of the neuron as soon as it’s produced
2. No receptors are involved; it diffuses into the target cell and activates second messengers
3. It can function as a retrograde transmitter by diffusing from the postsynaptic neuron back to the presynaptic neuron

Answer 19

Gas Neurotransmitter Differs from Other Transmitters