lecture 8 pt. 1

Question 1

how were NT discovered

Answer 1

otto loewi- discovered Ach by placing 2 hearts in seperate containers allowing the flow of fluid and stimulating 1

Question 2

neurotransmitter

Answer 2

chemical released by a neuron on a target with excitatory or inhibitory effect

Question 3

hormones

Answer 3

acn be same chemicals as NT but travel longer distances and are slower acting
- outside CNS

Question 4

synapse

Answer 4

junction where messenger molecules are released from one neuron to excite or inhibit the next
- most are chemical in mammals

Question 5

structure of synapse

Answer 5

presynaptic membrane- axon terminal
postsynaptic membrane - dendritic spine
synaptic cleft- space in between

Question 6

synaptic vesicle

Answer 6

presynaptic membrane bound spheres containing 1 or more NTs

Question 7

storage granule

Answer 7

presynaptic membranous compartments that hold several vesicles containing NT

Question 8

postsynaptic receptor

Answer 8

site to which NT molecule binds

Question 9

electrical synapse

Answer 9

gap junction- fused pre and post synaptic membrane allows ion to pass directly qnd exchange substances

• very fast
• not very flexible, cannot amplify/ dimish signals, cannot change with experience

Question 10

4 steps of neurotransmission

Answer 10

1. synthesis
2. release
3. receptor action
4. inactivation

Question 11

2 ways NT can be synthesized

Answer 11

1. axon terminal- building blocks from food pumped into cellfrom transporters
2. cell body- packaged at golgi bodies and transported on microtubules

Question 12

how are NT released

Answer 12

action potential opens up voltage gated Ca channels

• Ca then binds to camodulin forming a complex
• complex triggers release of vesicles to binding to presynaptic membrane and release into synapse

Question 13

quantum

Answer 13

the amount of NT in one vesicle- depends on:

• amount of Ca entering axon terminal
• number of vesicles docked and primed

Question 14

transmitter activated receptors

Answer 14

protein with binding site for specific NT

• may depolarize and cause EPSP or
• hyperpolarize and cause IPSP or
• initiate other reacitons to excite or inhibit other funcitons of receiving neurons

Question 15

4 ways of deactivation

Answer 15

1. diffusion
2. degradation - enzymes break down
3. reuptake - back into presynaptic axon terminal
4. astrocyte uptake

Question 16

excitatory vs inhibitory messages

Answer 16

excitatory:
- round vesicles, located on dendrites, dense material, wide cleft and large active zone
inhibitory synapse:
flat vesicles, located on cell body, sparse material, narrow cleft and small active zone

Question 17

4 criterea for NTs

Answer 17

1. must be present in neuron
2. must be released and produce response in cell
3. must activate in same way when experimentally placed
4. must be a mechanism for removal after work is done

Question 18

4 classes of NT

Answer 18

1. small molecule
2. peptide
3. lipid
4. gaseous

Question 19

characteristics of small molecules

Answer 19

quick acting and quick replaced
synthesized from dietary nutrients and packed into vesicles for use in axon terminals
- variety of functions
ex. Ach, histamine, DA, NE, EP, 5-HT, Glu, GABA

Question 20

peptide transmitters

Answer 20

chain of amino acids synthesized in the nucleus

• slow acting and slow to replace
• act as hormones that respond to stress, regulate eating, drinking, pleasure and pain, learning

Question 21

lipid transmitters

Answer 21

not soluble in water, not stored in vesicles so made on demand

• diffuse across cell membrane
  ex. endocannabinoids inhibit release of glutamate and GABA so dampen neuronal excitation and inhibition

Question 22

gases

Answer 22

not stored in vesicles, synthesized on demand, cross membrane

ex. NO, CO
- slow cellular metabolishm, control intestinal wall muscles and dilate blood vessels

Question 23

2 classes of receptors

Answer 23

1. ionitropic- binding site for NT and pore that flows ions
2. metabotropic- binding site for NT but no pore
   - linked to G protein that affects other receptors and produces changes in metabolic activity

Question 24

second messenger

Answer 24

chemical that carries a message to initiate a biochemical process

• activated by a NT
• alters ion flow in membrane channel, forms new ion channels