NERVOUS SYSTEM:Synaptic Transmission

Question 1

How do neurons make a connection with each other?

Answer 1

impulse arrives at end of axon
& crosses the synaptic cleft via synaptic transmission
NEURONS DO NOT TOUCH

Question 2

presynaptic membrane vs postsynaptic membrane

Answer 2

PRE- encloses synaptic vesicles with neurotransmitters
(chemical message manufactured by axon)
POST-contains protein receptor sites within the membrane for specific neurotransmitters

Question 3

Step 1 of synaptic transmission

Answer 3

impulse arrives at end of axon
-Na floods into axon terminal
THIS INCREASES VOLTAGE

Question 4

Step 2 of synaptic transmission

Answer 4

• calcium gates open

- Ca moves into axo bulb of presynaptic neuron

Question 5

Step 3 of synaptic transmission

Answer 5

-calcium binds to contractile proteins attached to the vesicles
-proteins contract and pull vesicles towards presynaptic membrane
USES ATP

Question 6

Step 4 of synaptic transmission

Answer 6

• exocytosis occurs and vesicles release neurotransmitters into the synaptic gap
• neurotransmitters diffuse

Question 7

Step 5 of synaptic transmission

Answer 7

neurotransmitters bind with receptor sites on postsynaptic membrane

Question 8

Step 6 of synaptic transmission

Answer 8

when neurotransmitters attach, voltage changes

• Na gates open due to this
• membrane depolarizes

Question 9

Step 7 of synaptic transmission

Answer 9

SYNAPSE BETWEEN-
axon and dendrite:action potential continues down the next neuron
axon and muscle cell: muscle contracts
axon and gland: hormone is released

Question 10

Step 8 of synaptic transmission

Answer 10

enzymes enter synaptic gap to destroy neurotransmitters

-gap returns to original condition

Question 11

Step 9 of synaptic transmission

Answer 11

Ca ions returned by active transport

Question 12

Can synaptic transmission happen in both directions?

Answer 12

NO

-axon has neurotransmitters and dendrite has receptors ONLY

Question 13

Where does the energy for the process come from?

Answer 13

Mitochondria

-abundance in synaptic gap/axon bulb

Question 14

what does the neurotransmitter ACETYLCHOLINE do?

Answer 14

promotes responses in a relaxed state
controls skeletal muscles
destroyed by ACETYLCHOLINESTERASE

Question 15

what does the neurotransmitter NORADRENALIN do?

Answer 15

excitatory transmitter (fight or flight)
increases activity of the receiving cell/tissue/organ
destroyed by monoamine oxidase

Question 16

How do drugs affect the synapse?

Answer 16

• hold receptors open for a long time
• block enzymes
• increase secretions
• imitate/mimic neurotransmitters
• stop neurotransmitters from joining receptors

Question 17

How does drug addiction work?

Answer 17

-some drugs bind to recyclers so NT cannot be removed from synapse causing neurons to increase rate of depolarization
-as a result, postsynaptic membrane decreases number of protein receptors
WHEN DRUG IS REMOVED
-NT amount goes back to normal but receptors do not
-makes getting high more difficult and you crave the drug