Pharm Block III

Question 1

Are leak channels open or closed at resting membrane potential?

Answer 1

Open

Question 2

Which ion takes advantage of leak channels and contributes to the resting membrane potential?

Answer 2

K - it can leak out

Question 3

What are 2 general mechanisms of EPSPs and give examples?

Answer 3

1. Inc. conductance to Na or Ca - nicotinic and several types of Glu receptors
2. Dec. conductance of a leak channel - comes from GPCRs, phos K channel by PKA - closure via Gs

Question 4

What are 2 general mechanisms of IPSPs and give examples?

Answer 4

1. Inc. conductance to Cl - GABA

2. GPCRs can open K channels

Question 5

Norepinephrine is synthesized from ____________.

Answer 5

Tyrosine

Question 6

What is the rate limiting step in norepinephrine synthesis?

Answer 6

Tyr → Levo-dopa via tyrosine hydroxylase

Question 7

Where is dopamine β-hydroxylase located and what is its function?

Answer 7

Synaptic vesicles, converts dopamine to NE

Question 8

VMAT

Answer 8

Pumps dopamine into synaptic vesicles and pumps out H+

Question 9

NAT

Answer 9

Plasma membrane transporters on axon terminal take up NE - work in reverse w/ amphetamine around

Question 10

What is one way in which NE release is inhibited?

Answer 10

α2 autoreceptors - dec Ca2+ sensitivity - feedback inhibition

Question 11

What is one way in which NE release is increased?

Answer 11

β receptors - inc. cAMP, more Ca2+ - feedforward regulation

Question 12

What are 3 methods of neuronal reuptake of NE?

Answer 12

1. NET - selective
2. Na symporter
3. Pumped back in vesicles by VMAT

Question 13

What are 2 enzymes that break down NE and where are they located?

Answer 13

1. MAO - cytosolic in presynaptic cell

2. Catechol-O-methyl-tranferase in postsynaptic cell

Question 14

Neurotensin is a ___________ transmitter and is always co-localized with ____________.

Answer 14

Neuropeptide

Dopamine

Question 15

Neurotensin release requires high levels of ____ that can be seen during ____________________.

Answer 15

Calcium

High intensity, rapid firing of neurons

Question 16

Neurotensin undergoes _________ release which has what effect on signaling?

Answer 16

Extrasynaptic
Targeting is less directed
can find receptors on postsynaptic nerves farther away
Not 1:1 signaling

Question 17

How is neurotensin inactivated?

Answer 17

1. Extracellular peptidases
2. Diffusion
   * *NO REUPTAKE

Question 18

General anestheisa

Answer 18

State of pt in which no movement occurs in response to a painful sitmuli

Question 19

What are 4 characteristics of the general anesthetic state?

Answer 19

1 . Amnesia

2. Unconsciousness
3. Analgesia
4. Noxious stimuli don’t evoke movement/autonomic response

Question 20

Potency

Answer 20

Dose of anesthetic that prevents movement in response to pain in 50% of pts

Question 21

A dose of gas is directly related to/determined by its ___________________.

Answer 21

Concentration at the alveolus

Question 22

Minimum alveolar concentration

Answer 22

MAC that prevents movement in 50% of patients

Question 23

What are two mechanisms by which anesthetics work?

Answer 23

1. Open GABA - Cl channel - hyperpolarize

2. Inhibit NMDA: reduced Na and Ca influx - not as effective as opening GABA

Question 24

What are three characteristics of parenterally administered general anesthetics?

Answer 24

1. Hydrophobic
2. Rapid CNS effect
3. Duration of action is shorter than half life

Question 25

Sodium Thiopental

Answer 25

Activates GABAa receptors
Induces anesthesia
12 hour half life
Can produce hangover
CNS/Resp depression + venodilation

Question 26

Propofol

Answer 26

Activates GABAa 
Induces/maintains
3.5 hr. half life, antimimetic
CNS/Resp depression, vasodilation
SE: Pain on injection, drop in BP, blunt baroreflexes, initial excitation

Question 27

Etomidate

Answer 27

Induces, little effect on BP - lots of pain on injection, N/V
75 min half life
Non-analgesic

Question 28

Ketamine

Answer 28

NMDA antagonist
Induces/maintains 2.5-3 hr half life
Dissociative anesthesia
SE: nystagmus, salivation, lacrimation, inc. in muscle tone, SNS stim