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Flashcards in Neurotransmitterrs Deck (65):
1

Glia

Astro Yates, oligodendrocytes and Schwann cells and microglia

2

Dendrites

Input, increase contact expanse

3

Dendritic spines

Increase SA for axonal contact

4

Cell body

Maintenance factory

5

Axon

Output, can reach distances far away

6

Myelin sheath

Insulation for electrical signaling

7

Synaptic buttons

Chemical signaling, neurotransmitters

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Axon hillock

Action potential generated

9

Sensory neurons

Receptors in periphery, cell body in ganglion

10

Motor neurons

Cell body in CNS for skeletal motor neurons

Cell body in autonomic ganglia for smooth muscle

11

Interneurons

Contained in CNS

Travel from one brain region to another and local confined to cell body

12

Internal structure neurons

High protein synthesis and neurotransmitter

Ribosomes and rough ER

cytoskeleton components- microtubules, neurofilsments and microfilaments

13

Spinal cord circuitry

Gray matter in 10'layers, Latina

Peripheral into spinal cord via dorsal roots and dorsal root ganglia contain cell bodies of sensory axons

Ventral horn and intermediate zone contain cell bodies of motor neurons whose axons travel in ventral root

14

Peripheral nerves

Epineurium, perineurium snd endoneurium

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Epineurium

Fibroblasts and collagen sheath containing peri and epineurium and peripheral axons

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Perineurium

Connective tissue sheath containing bundles of peripheral nerve axons

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Endoneurium

Connective tissue sheath surrounding individual axons

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Schwann cell

Unmyelinated in PNS

19

Glial cell factors

Do not form synapses

Electrically unexcitable, no action potential

Only 1 process and some divide, numerous as neurons

20

Astrocytes

Provide structural matrix- blood brain barrier

Homeostasis- K and glucose, and neurotransmitters

Scar following injury

Many different types and shapes

21

Blood brain barrier

Surrounding capillary with endothelial cells forming tight junction

Pedicures with smooth muscle like property and astroglial end feet

22

Myelin producing cells

Oligodendrocytes and Schwann cells

1 oligo forms many myelin segments CNS and insulate against signal degradation

Segmentally organized nodes of Ranvier

Schwann cells can act like CNS glial cells but are PNS, create ECM and can phagocytose

23

Microglia

Ubiquitous, numerous, plasticity, immune competence- can become brain macrophages and self renewal

24

Ependymal cells

Line ventricular system

Circulate CSF via cilia

Choroid plexus cells produce and secrete CSF

CSF during sleep removes metabolites

25

Three compartments and three interfaces

Blood-CNS

CNS-CSF

CSF- blood

So glucose can pass through blood brain barrier

26

Cerebral cortex

6 layers

Pyramidial cells (3 and 5)
Long axons of cortex
Projects to other neurons in cerebral cortex
Projects structures outside cerebral cortex

Layer 4 is the inner granular layer and receives info from thalamus

27

Projection neurons

Large dendritic arborizations

Large cell bodies and long axons

Important for information processing between structures

28

Interneurons

Small neurons with smaller dendritic arborizations

Small cell bodies short axons

Project short distances

Local info processing

29

Hippocampal formation

3 layers, connects with thalamus, amygdala and septal nuclei

Dentate gyrus- input cells of hippocampus
CA region- pyramidial cells, output cells (hippocampus proper)

Memories of facts via connection to thalamus

Amnesia

30

Cerebellum

Molecular, purkinje cell layer and granule layer

Granule cell axon to molecular layer as parallel fibers and synapses with dendrite of purkinje cell which is major output and connects with Brain stem and thalamus

Motor movement

31

Purkinje cells

Largest neurons in Brian

Receive ~100,000 synapses

32

Primary site for neurochemical communication

Synapse or neuroeffector junction

33

Electrical synapse

Fast communication, no signal amplification ( cardiac, GI, fast neural tissue)

Not target for drug action

34

Chemical synapses

Slower but amplification, targeted by drugs and signal computation

Axon to Nerve and dendrite or to cell body

Usually unidirectional (except nitric oxide)

Fast or slow, thousands of synapses

Active zone for rapid fusion and stored transmitter release, exocytosis

35

Synapse types

Fast: ligand gated ion channel

Slow: G protein coupled receptor

36

CNS Neurotransmitter

Endogenous substances used to transmit signals to cells across synapse

May exert excitatory and inhibitory actions on target, and response depends on if activates and the receptor effector coupling mechanism

37

Acetylcholine

CNS Somatic motor neurons, skeletal muscle

Excitatory and used in memory

38

Dopamine

Pleasure when released to reward circuits

Movement, mood and reward

CNS

39

GABA

Major inhibitory neurotransmitter of Brain

40

Glutamate

Major excitatory neurotransmitter of the brain

41

Norepinephrine

Can also act as hormone, CNS

In peripheral, fight or flight

In Brain- attention, wakefulness, pain

42

Serotonin

Mood aggression, sensory

CNS, in spinal cord used as inhibitory pain pathway

43

Opioid peptides

CNS role in pain perception and mood

In addition option exert GI action

44

5 requirements for endogenous substance to be considered synaptic neurotransmitter

Present in presynaptic nerves sequestered in synaptic vesicles

Mechanism must exist for synthesis or accumulation of the substance within presynpatic nerve

Mechanism for inactivation must exist within synaptic region, degradation enzymes, reuptake system or other

45

Neurotransmitter pathways

NT formed and stored within specific nerve cells

Different classes clustered in regions of the brain

46

Synaptic vehicle formation, transport and NT loading

Large quantities typically stored in synaptic vesicles and held for release at presynaptic axon termini

Processes differ for small amine transmitters vs. peptide transmitters

47

Small molecule NT

Vesicles formed in cell body and transported to termini without NT

Synthesized locally and packaged into small clear core vesicles at Nerve terminal

Vesicles recycled and reloaded with NT after release

48

Neuropeptide NT

NT precursor synthesized within body on ER

Precursors and processing enzymes loaded to dense core vesicles in cell body and transported to nerve terminal with the processing enzymes

Little evidence for vesicle recycling

49

Chemical neurotransmission

NT formation and storage in synaptic vesicles
Synaptic transmission: stimulation of release, activation of receptors, target cell response to receptor activation, termination of NT action

50

Synaptic neurotransmission steps 1

1. Stimulation of NT release- action potentional. Ca rush into nerve terminal which causes vesicle to fuse and release contents into extra cellular space (synapse)

Vesicle membrane re captured by endocytosis and recycled back into synaptic vesicles, vesicles then reloaded with NT

51

Transmitter release

Limited circumstances where there appears to be a therapeutic benefit derived from the use of agents that alter NT release

52

Synaptic transmission 2

NT activation of captors on postsynaptic cells

Once release NT bind and activate receptor classes which changes target cell channels, enzymes and messengers

Receptor activation can excite or inhibit target cell and then do not respond if lack appropriate receptors

Therapeutic intervention- agonists and antagonist

53

GABA-A Receptors

Regulate opening of Cl channels

Major inhibitory AA transmitter in CNS

54

GLU

excitatory AA transmitter in CNS

Drugs that mimic or enhance GLU are excitatory

55

CNS depression by enhanced inhibitory neurotransmission

DIAZEPAM- benzodiazepine

Sedative, enhance GABA to stimulate Cl channel opening so have membrane hyperpolarization and deceased neuronal excitability

56

CNS depression by reduced excitatory transmission

Ketamine

Blocks GLU activation of NMDA receptors

In normal animals NMDA increases Na and Ca into neurons and membrane depolarization to increase neuron excitability

57

Transmitter receptor activation

Vital process that is common target for numerous drugs of therapeutic importance

58

Synaptic neurotransmission 4

Elimination of NT from synapse

To terminate signal NT must be removed and elimination processes are conserved

Certain NT elimination processes are major targets for therapeutic drug intervention (inhibitors)

Inhibition of NT elimination will enhance NT action

59

Uptake reuptake transport

Termination of NT action

60

Act elimination

AChE enzymes

61

DA elimination

Uptake by dopamine transporters

Metabolic degradation- MAO

62

GABA elimination and GLU elimination

Uptake by glutamate transporters or metabolic degradation

63

NE elimination

Uptake by catecholamine transports or metabolic degradation

64

5-HT elimination

Uptake by serotonin receptors or metabolic degradation

65

Acetylcholine degradation ex

Rapidly hydrolyzed by AChE at all sites where works as NT

If inhibit half life is high