Class 1: Intro

Question 1

Synapse

Answer 1

Point of connection at which a neuron communicates with another cell (usually another neuron)

Question 2

Two types of synapses

Answer 2

1. chemical (separated by a synaptic cleft; transmission via neurotransmitters)
2. electrical (aka gap junctions). Super speedy

Question 3

Propagation of a nerve impulse: Presynaptic

Answer 3

Action potiential reaches axon bulb

Voltage gated Ca+ open –> Ca+ floods into neuron

Vesicles migrate to cell membrane and exocytose their contents into synaptic cleft

Question 4

Propagation of a nerve impulse: Postsynaptic

Answer 4

Neurotransmitters fit into receptors on post-synaptic membrane

Excitatory NTs cause Na+ channels to open, depolarizing (making more positive) the inside of the cell.

If the postsynaptic potential reaches -70 mV, then voltage gated Na+ channels open, propagating AP down cell.

Question 5

Excitatory PostSynaptic Potential (EPSP)

Answer 5

Depolarizing postsynaptic potential

May take a number of EPSPs in order to reach threshold required to initiate a nerve impulse

Question 6

Inhibitory PostSynaptic Potential (IPSP)

Answer 6

Hyperpolarizing postsynaptic potential.

Makes the inside more negative, thus making it more difficult to generate an action potential

Question 7

What channels are opened up by inhibitory NTs?

Answer 7

K+ (outbound) and/or Cl- (inbound)

Question 8

What is the main excitatory NTs?

Answer 8

ACh (at neuromuscular junctions)

Glutamate (CNS)

Question 9

How are NTs removed from synaptic cleft?

Answer 9

1. diffusion
2. enzymatic degradaton (ie ACh-esterase)
3. reuptake by cell (another form of receptor-mediated endocytosis)

Question 10

Serotonin

Answer 10

5HT (hydroxytryptamine)
Monoamine
Converted from tryptophan by B6
80% in GI tract. Also brain, smooth muscle

Excitatory

Affects mood, sleep, pain, appetite

Question 11

What enzyme breaks down serotonin?

Answer 11

MAO (monoamine oxidase)

Question 12

“Modulator” NTs

Answer 12

Slower acting, longer lasting.

Include 5HT, DA, NE and many small peptide molecules.

Question 13

Dopamine

Answer 13

Amine

Excitatory (and inhibitory)
Brain, smooth muscle

Controls arousal levels

Question 14

Norepinephrine

Answer 14

Amine

Excitatory
Brain, smooth muscle

Induce arousal, heighten mood

Question 15

Acetylcholine

Answer 15

Acetic acid

Excitatory and inhibitory

PNS, brainstem

Memory, vasodilation

Question 16

GABA

Answer 16

amino acid

Inhibitory

Brain

Controls anxiety levels

Question 17

Enkephalin

Answer 17

Neuropeptide (opiate)

Inhibitory

Brain, spinal cord

Reduce stress, promotes calm, analgesic

Question 18

What are the three main endogenous opiates

Answer 18

Enkephalin
Endorphin
Dynorphin

Question 19

Dale’s Principle

Answer 19

Belief that only one neurotransmitter is produced by each neurofibre. Incorrect

Question 20

A single nerve cell may have how many synapses?

Answer 20

Hundreds or thousands; however each input may be so small that many inputs are required for an action potential to be generated.

Question 21

Nicotine

Answer 21

ACh agonist

Question 22

Curare

Answer 22

ACh antagonist at NMjunction. Blocks muscle contraction

Question 23

Cocaine

Answer 23

Blocks DA reuptake

Question 24

Sarin (and similar nerve agents)

Answer 24

Blocks ACh-esterase

Question 25

Myasthenia gravis

Answer 25

Destruction of ACh receptors at NMjunction

Question 26

Neuropil

Answer 26

Dense tangle of dendrites, axon terminals, and glial cells in CNS. Where most synaptic connectivity occurs

Question 27

The components of a Neural Circuit

Answer 27

1. afferent 2. efferent 3. interneuron

Question 28

Myotatic Reflex

Answer 28

1. Hammer tap stretches tendon --> afferent fibre to dorsal root ganglion 2. Afferent fibre synapses with Efferent fibre in ventral horn, which activates extensor muscle(s) 3. Afferent fibre also synapses with Interneuron, with synapses with a different Efferent fibre, which inhibits the antagonist (flexor) muscle

Question 29

Neuronal Pool

Answer 29

Group of interconnected neurons with a specific function | Patterns of interaction can be diagrammed as a "neural circuit"

Question 30

Five Neural Circuit patterns

Answer 30

1. divergence 2. convergence 3. serial processing 4. parallel processing 5. reverberation

Question 31

Divergence

Answer 31

Spread of information from one neuron to many Allows broad distribution of signal ie. sensory neurons --> neuronal pools throughout SC and brain

Question 32

Convergence

Answer 32

Several neurons synapse with one postsynaptic neuron Can allow for one motor neuron to be under both coscious and nonconscious control

Question 33

Serial Processing

Answer 33

Stepwise relay of information from one neuron or neuronal pool to another ex pain pathways

Question 34

Parallel processing

Answer 34

Divergence then serial processing Allows for diverse simultaneous responses

Question 35

Reverberation

Answer 35

Positive feedback loop constantly stimulating presynaptic neuron Will continue until synaptic fatigue or inhibitory stimuli Consciousness, muscular coordination, normal breathing