EXAM I Intro to the Nervous System Flashcards Preview

Human Disease and Therapeutics > EXAM I Intro to the Nervous System > Flashcards

Flashcards in EXAM I Intro to the Nervous System Deck (29):
1

describe the general principles of direct actions of neurotransmitters

  • NT binds to and opens ion channels
  • promotes rapid responses by altering membrane potential

2

describe the general principles of indirect actions of neurotransmitters

  • NT acts through intracellular second messengers, usually G protein pathways
  • broader, longer-lasting effects

3

___ is an excitatory neurotransmitter

glutamate

4

___ and ___ are inhibitory neurotransmitters

dopamine and GABA

5

___, ___, and ___ are both excitatory and inhibitory neurotransmitters

acetylcholine, norepinephrine, and serotonin

6

is GABA a direct or indirect acting neurotransmitter?

direct

7

___ membrane channels open and close in response to voltage changes across the membrane; what are some examples?

  • voltage-gated
  • examples: voltage-gated Na+ channels and lidocaine

8

___ membrane channels involve a hormone, drug, or transmitter than bind to the protein and the channel opens up; what are some examples?

  • ligand-gated (ionotropic)
  • examples: glutamate (AMPA), nicotine ACh receptors, and GABA

9

what is the action length of ligand-gated (ionotropic) receptors?

action is immediate and brief

10

are ligand-gated (ionotropic) receptors excitatory or inhibitory?

  • some are excitatory and open channels for small cations
  • some are inhibitory and allow Cl- influx or K+ efflux to cause hyperpolarization

11

T or F:

metabotropic receptors are not directly linked to ion channels

true

12

how do metabotropic receptors work?

  • initiates a biochemical process that mediates more long-term effects and modifies the responsiveness of the neuron
  • NT acts as the first messenger which activates a second messenger that in turn changes the excitability of a neuron

13

what are the two types of metabotropic receptors?

  • membrane-delimited - occur entirely in plane of membrane
    • when G-proteins interact with calcium channels, they inhibit channel function (presynaptic inhibition)
    • when G-proteins interact with K+ channels, they open (activate) channels causing postsynaptic inhibition
  • diffusible second messengers

14

what are examples of diffusible second messengers (metabotropic)?

beta-adrenergic receptors and cAMP

15

___ are receptors on an axon terminal through which the neuron's own NT can influence the function of the terminal (usually inhibitory) - for example, D2 receptors

autoreceptors

16

___ are receptors on an axon terminal through which NTs from other neuronal types can influence the function of the terminal

heteroreceptor

17

what are the 3 catecholamines?

dopamine, norepinephrine, and epinephrine

18

___ can act like dopamine due to its similar structure

amphetamine

19

which enzyme catalyzes the conversion of NE to epi?

phenylethanolamine-N-methyltransferase (PNMT)

20

epinephrine is typically made by ___, but can also be made by some ___

  • adrenal medullary cells
  • CNS neurons

21

what is a monoamine?

one amino group connected to an aromatic group by a 2-carbon chain

22

what are 3 exmamples of monoamines?

catecholamines, serotonin, histamine

23

is serotonin a catecholamine?

no, it is an indoleamine

24

which amino acid is inhibitory?

GABA

25

which amino acid is excitatory?

glutamate

26

H3 (histamine) receptor is thought to function as an ___

inhibitory heteroreceptor

thus, activtaion of brain H3 receptors decreases the release of acetylcholine, dopamine, norepinephrine, serotonin, and certain peptides

27

what is neurotensin? where is it found?

  • a neuropeptide that acts as an endogenous neuroleptic and regulates dopamine systems (inhibitory feedback)
  • it is found in the GI tract (inhibits GI motility) and circulation (causes vasodilation)

28

describe nitric oxide

  • gaseous signaling molecule
  • CNS role is controversial
  • relaxes vascular smooth muscle

29

how do endorphins make you happy?

endorphins bind to µ receptors, causing a decrease in GABA release, which causes an increase in dopamine release (= happy feeling)