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Brain And Behaviour > Topic 5 > Flashcards

Topic 5 Flashcards

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The Brain flashcards
1
Q

Define neurotransmitter

A

Chemical released into a neuron with an inhibitory or excitatory effect

Chemicals circulating the bloodstream outside of the CNS are hormones

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2
Q

Otto Loewi experiment

A

Discovered the role of the vagus nerve and acetylcholine in slowing the heart

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3
Q

Characteristics of acetylcholine

A

Excitatory for skeletal muscles (somatic system)

Inhibitory for internal organs (autonomic system)

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4
Q

Chemical synapse

A

Neurotransmitters are released from one neuron to excite or inhibit the next neuron
- presynaptic membrane (axon terminal)
- postsynaptic membrane (dendrites)
- synaptic cleft
- tripartite synapse (synthesize, protect, and break down NTs)
- synaptic vesicles
- storage granule (holds vesicles)
- postsynaptic receptor
- anterograde synaptic transmission (NTs binding to post receptors)
- transporter

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5
Q

Steps of anterograde synaptic transmission

A
  1. NTs are synthesized in the neuron
    - small in axon terminal, according to diet, transporters
    - big in cell body, according to DNA, microtubules
    2.NTs are packaged and stored in vesicles
  2. AP opens voltage gated Ca channels —> exocytosis
    - Ca binds to calmodulin protein to form a complex
    - complex causes exocytosis
  3. NTs bind to and activate receptors on the postsynaptic membrane
    - depolarize postsynaptic membrane (EPSP with influx of Na)
    - Hyperpolarize postsynaptic membrane (IPSP with efflux of K or influx of Cl)
    - autoreceptors are receptors on the pre membrane that cause negative feedback
  4. NTs are degraded or removed
    - diffuse away from cleft
    - degraded by enzymes
    - retaken by the presynaptic membrane
    - astrocyte uptake an brought back to axon terminal
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6
Q

Antidepressants

A
  • serotonin transporter and norepinephrine transporter
    (Tricyclic antidepressants, SSRI, SNRI)
  • monoamine axidase
    (Inhibits MAO enzymes, preventing breakdown of serotonin and norepinephrine)
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7
Q

Types of synapses (8)

A

Dendrodendritic
Axodendritic
Axoextracellular
Axosomatic
Axosynaptic
Axoaxonic
Axosecretory
Axomuscular

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8
Q

Electrical synapses

A

Gap junction - fused pre and post membranes that allow AP to pass through
- faster than chemical synapses
- groups of cells fire synchronously
- less flexible

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9
Q

Excitatory vs Inhibitory synapse

A

Excitatory
- located on dendrites
- round vesicles
- wide cleft
- large active zone

Inhibitory
- located on cell body
- flat vesicles
- narrow cleft
- small active zone

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10
Q

Characteristics of NTs

A
  1. Transmitter must be synthesize in the neuron
  2. Chemical must be released and produce a response on a target when neuron is active
  3. Response must be constant when experimentally placed on target
  4. Must be a mechanism for removing excess transmitter

May also
1. Carry messages between neurons
2. Change the synapse structure
3. Send retrograde messages to communicate

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11
Q

Classes of neurotransmitters

A

Small molecule transmitter
Peptide transmitter
Lipid transmitter
Gaseous transmitter

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12
Q

Small molecule transmitters

A
  • quick acting
  • synthesized from dietary nutrients
  • packaged in axon terminals
    Amino acids
  • glutamate (main excitatory)
  • GABA (main inhibitory)
  • glycine
    Amines
  • dopamine
  • norepinephrine
  • epinephrine
  • serotonin
    Acetylcholine
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13
Q

Peptide transmitters

A

Neuropeptides
- synthesized through translation of mRNA
- assembled in neurons ribosomes
- transported by microtubules
- act slowly and not replaced quickly
-stress related hormones, eating drinking regulation, etc.
- opioids
- neurohypophyseals
- secretins
- insulins
- gastrins
- somatostatins
- tachykinins

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14
Q

Lipid transmitters

A
  • lipophilic molecules
  • non soluble in water
  • not stored in vesicles
    Ex. Endocannabinoids
  • retrograde transmitter
  • synthesized in post and acts on pre
  • reduces amount of NT released
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15
Q

Gaseous transmitter

A

Synthesized in cell as needed and easily cross membranes
Ex. Nitric oxide

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16
Q

Ionotropic receptor

A
  • ion channels
  • membrane with a binding site and a pore that regulates flow
  • NT attaches, protein changes shape, pore opens or closes
  • rapid effects
  • directly changes membrane voltage
17
Q

Metabotropic receptor

A
  • membrane protein with a binding site for NTs
  • no pore
  • indirectly produces changes in ion channels, metabolic activity, or gene expression
  • linked to g proteins
  • slow developing effects but longer lasting and more variable

Nt binds to receptor, activates G protein, alpha subunit binds to ion channel or enzyme

18
Q

G protein and second messengers

A
  • membrane receptor
  • alpha beta and gamma subunits
  • amplification cascade
  • alter channel flow, cells metabolic process, or gene expression
19
Q

Receptor subtypes

A

Each subtypes have different properties, resulting in different effects from same NTs

20
Q

Somatic Motor Efferents

A
  • innervate skeletal muscle
  • acetylcholine excites muscle causing contractions
  • nicotinic acetylcholine receptor permits efflux of K and influx of Na
21
Q

Somatic Sensory Afferents

A
  • AP causes stretch activated channels on dendrites to open
  • influx of Na
  • voltage gated Na and K channels open
  • nerve impulses produced
22
Q

Activating system

A
  • CNS
  • neural pathways that coordinate brain activity through a single NT
  • cell bodies in nucleus in brain stem
  • axons throughout the brain
23
Q

Cholinergic system

A

Acetylcholine
- maintaining attention
- waking EEG patterns
- memory by maintaining neuron excitability
- decrease in ACh is related to Alzheimer’s disease

24
Q

Dopaminergic system

A

Dopamine
Nigrostriatal
- maintains normal motor behaviour
- loss of DA leads to muscle rigidity and dyskinesia in Parkinson’s
Mesolimbic
- repetition in behaviour
- most affected by addictive drugs and behavioural addictions
- increases in DA related to schizophrenia
- decreases in DA related to attention deficits

25
Q

Noradrenergic system

A

Norepinephrine
- maintains emotional tone
- decreases in NE related to depression, hyperactivity, and attention deficit
- increases in NE related to mania

Brain And Behaviour (11 decks)

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