Nervous System: Synaptic Transmission

Question 1

Define Synapses

Answer 1

• Space between neurons and effectors (muscles, glands, organs)
• neurons don’t touch each other
• terminal branch of a neuron allows it to join with many different neurons
• communication between neurons is thru chemicals called neurotransmitters

Question 2

What are the neurons involved with synapses

Answer 2

• presynaptic neuron

- postsynaptic neuron

Question 3

Define Presynaptic neuron

Answer 3

neuron that carries impulses to synapses

- releases neutrotransmitters into synapse from synaptic knobs

Question 4

Define Postsynaptic neuron

Answer 4

neuron that carries impulse away from synapses

• Have receptors for neutrotransmitters
• neurotransmitters alter permeability of post-synaptic cell

Question 5

Define synaptic knob

Answer 5

• endplate/ axon terminal
• swellings on end of axon
• contain synaptic vesticles that produce and store NT

Question 6

Define synaptic vesticles

Answer 6

sacs of NT released into synapse

Question 7

Define neuroransmitters

Answer 7

• chemicals which inhibit or excite neighboring neurons
• released from vesicles in presynaptic membrane into synaptic cleft, altering membrane potentials of postsynaptic neurons

Question 8

Path during a synaptic transmission

Answer 8

• action pot. in presynaptic neuron reaches axon terminal
• Ca+ channels open to let Ca into presynaptic neuron
• Calcium causes synaptic vesicles to fuse w/ membrane
• NT in vesicles are released into synaptic cleft and move across space to bind to receptors on postsynaptic membrane

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Question 9

Excitatory Neurotransmitter

Answer 9

• open Na+ channels
• make Na rush into post synaptic neuron
• causing depolarization
• action pot. if threshold is reached

Question 10

Inhibitory Neurotransmitter

Answer 10

• Open K+ gates
• move out of neuron causing hyperpolarization
• no action pot

Question 11

Name Neurotransmitters

Answer 11

• Acetylcholine
• Glutamate
• Noradrenaline/Norepinephrine
• Dopamine
• Serotonin
• GABA

Question 12

GABA

Answer 12

• most common NT in brain
• Inhibitory
• produced in CNS
• Effects: controls motor behaviour by causing relaxation, reduce stress n anxiety, increase
  focus
• Alcohol stimulates GABA
• Deficiency in GABA can cause: anxiety, irritability, headaches, seizures, low sex drive, heart disorders, depression

Question 13

Acetylcholine

Answer 13

• Most common NT in body
• produced in PNS n CNS
• in cns: inhibitor to heart muscles
• in pns: connect motor nerves to muscles
• excitatory to skeletal muscles
• associated w/ learning,memory, arousal
• Major effect: skeletal muscle contraction
• Decrease of production can lead to Alzheimers bcs of loss of memory n mental capacity

Question 14

Cholinesterase

Answer 14

• aka Acetylcholinesterase
• produced in PNS n CNS
• Enzyme released from presynaptic membrane after acetylcholine
• Effect: break down acetylcholine to be recycled
• when broken down, Na channels close, starting neuron recovery
• if acetylcholine is not broken down, neuron would always be excited

Question 15

Glutamate

Answer 15

• Excitatory NT in brain n spinal cord (CNS)

- Effect: learning n memory

Question 16

Noradrenaline/Norepinephrine

Answer 16

• produced by adrenal glands during flight or fight response
• produced in PNS n CNS
• Excitatory or inhibitory
• Effect: speeds up nerve transmission at synapse, inc blood sugar lvls, effect wakefulness, inhibits digestion, inhibits sexual excitement

Question 17

Dopamine

Answer 17

• Excitatory
• produced in CNS n PNS
• Effect: control voluntary movements and emotional response, ability to feel pleasure n pain
• Decreased production of dopamine result in parkinsons bcs of involuntary muscle contractions and tremors

Question 18

Serotonin

Answer 18

• Inhibitory
• produced in CNS
• Effect: sleep, temp., sensory perception, mood control

Question 19

Summation

Answer 19

• more than one presynaptic neuron is connected to a post synaptic neuron, causing more NT to excite or inhibit the neuron