mod 18

Question 1

is a state characterized by reversible loss of
perception of pain or other motor response to
stimuli in a local or regional part of the body, and is not accompanied by loss of consciousness

Answer 1

local or regional anesthesia

Question 2

indications of local or regional anesthesia

Answer 2

•Used during minor surgery
•To numb an area of the body so the procedure
can be performed

Question 3

substances which when applied about the nerve
terminals or nerve fiber prevent conduction of both sensory and motor impulses in axons and dendrites

Answer 3

local anesthetics

Question 4

are distinguished from the muscle relaxants which block normal neural transmission at the neuromuscular junction synapse

Answer 4

local anesthetics

Question 5

membrane of nerve cell has channel proteins to allow passage of electrically charged molecules called

Answer 5

ions

Question 6

initiates a nerve impulse

Answer 6

pain, pressure, temperature

Question 7

is the first local anesthetic discovered

Answer 7

cocaine

Question 8

for a nerve impulse to be generated in a neuron there needs to be a?

Answer 8

threshold of electrical activity to be reached

DEPOLARIZATION

Question 9

What is the charge on the outside of a neuron at rest?

Answer 9

positive

Question 10

What is the charge on the inside of a neuron at rest?

Answer 10

negative

Question 11

in depolarization, sodium moves IN or OUT?

Answer 11

in

Question 12

in depolarization, sodium moves IN or OUT?

Answer 12

in

Question 13

What causes channel proteins in the neuron membrane to open?

Answer 13

stimulus

Question 14

During depolarization, which ion moves into the neuron?

Answer 14

3 sodium (Na+)

Question 15

During depolarization, which ion moves out of the neuron?

Answer 15

2 potassium (K+)

Question 16

What happens to the inside of the neuron when sodium (Na⁺) moves in?

Answer 16

becomes positive

3 sodium in, 2 potassium out

Question 17

What is the ratio of sodium to potassium movement?

Answer 17

3 sodium in, 2 potassium out

Question 18

in depolarization, the neuron becomes more positive or negative?

Answer 18

positive

Question 19

depolarization occurs in what manner?

Answer 19

occurs in a wave

Question 20

What does local anesthesia block?

Answer 20

It blocks sodium (Na⁺) and potassium (K⁺) channels in the nerve membrane.

Question 21

What is the effect of blocking sodium channels?

Answer 21

Sodium ions can’t enter the neuron, so depolarization cannot occur.

Question 22

What happens to the charge inside the neuron when sodium can’t enter?

Answer 22

The inside of the neuron stays negative, and no action potential is generated.

Question 23

What is the overall result of local anesthesia on nerve function?

Answer 23

No depolarization means no nerve impulse, so pain signals are blocked — you don’t feel pain in that area.

Question 24

Why is depolarization important for nerve impulses?

Answer 24

Depolarization allows the neuron to send an electrical signal (action potential). Without it, the nerve can’t transmit messages.

Question 25

How do local anesthetic particles work at the molecular level?

Answer 25

They **bind to and block voltage-gated sodium channels**, preventing Na⁺ from entering during stimulation.

Question 26

What happens to the resting membrane potential when local anesthesia is applied?

Answer 26

The resting membrane potential **stays negative**, and the neuron remains **inactive**

Question 27

Why does the body part feel numb after local anesthesia?

Answer 27

Because **nerve impulses can’t travel**, the brain receives no sensation signals from that area.

Question 28

what local anesthetic affect more? non myelinated or myelinated nerve fibers

Answer 28

non myelinated nerve fibers

Question 29

myelinated fibers are affected only at the?

Answer 29

nodes of Ranvier (devoid of myelin)

Question 30

The order of sensory blockade is as follows

Answer 30

sympathetic outflow ➡️ pain ➡️ thermal and propioceptive sensations ➡️ motor activity

Question 31

The highly lipid soluble local anesthetics which may cause **greater motor blockade** than sensory blockade.

Answer 31

etidocaine

Question 32

MOA of local anesthetic

Answer 32

• After injection, the uncharged (unporotonated) form passes through the connective tissues surrounding the nerve fiber and through the plasma membrane to the axoplasm. • Inside the neuron, the local anesthetic ionizes due to lower pH in the axoplasm. • The cationic form of the drug then attaches to the internal sodium gate, thus decreasing the sodium

Question 33

In what form does a local anesthetic cross the nerve membrane?

Answer 33

In its uncharged (unprotonated) form.

Question 34

Why must the uncharged form be present for the anesthetic to enter the neuron?

Answer 34

Because only the lipid-soluble uncharged form can diffuse through the nerve’s lipid membrane.

Question 35

What happens to the local anesthetic once it is inside the neuron?

Answer 35

It becomes ionized (charged) due to the lower pH of the axoplasm.

Question 36

Which form of the anesthetic actually blocks the sodium channel?

Answer 36

cationic (charged) form

Question 37

Where does the local anesthetic bind to block sodium movement?

Answer 37

It binds to the internal portion of the voltage-gated sodium (Na⁺) channel

Question 38

Why does the local anesthetic ionize inside the axoplasm?

Answer 38

Because the axoplasm has a lower (more acidic) pH, which favors ionization.

Question 39

Which form of the drug is responsible for **diffusion** across membranes, and which for **channel blockade**?

Answer 39

- Uncharged form → crosses membrane - Charged form (cationic) → blocks sodium channel

Question 40

3 PARTS OF MOST USEFUL ANESTHETICS

Answer 40

•aromatic ring (lipophilic group) •intermediate chain •amino group

Question 41

intermediate chain can be an ?

Answer 41

ester or amide

Question 42

enumerate Ester Local Anesthetics

Answer 42

cocaine benzocaine tetracaine procaine

Question 43

enumerate Amide Local Anesthetics

Answer 43

lidocaine bupivacaine mepivacaine prilocaine ropivacaine

Question 44

helpful tip in memorizing AMIDE ANESTHETICS

Answer 44

•Amide anesthetics have an extra “i” letter prior to –caine suffix Lidocaine Mepivacaine Bupivacaine Etidocaine Prilocaine Dibucaine

Question 45

THE TYPE OF INTERMEDIATE CHAIN DETERMINES:

Answer 45

- Biotransformation - Allergenecity - Stability - Toxicity - Acid dissociation constant (PKa) - Onset of Action - Drug interaction

Question 46

True or False Most local anesthetics are weak acids

Answer 46

False **weak bases**, which are less soluble in aqueous solutions.

Question 47

The solubility of local anesthetics is increased in solutions of low or high pH?

Answer 47

low pH

Question 48

like any other weak bases ionize in alkaline medium

Answer 48

local anesthetics

Question 49

pH of Ester LA

Answer 49

8.5 - 9

Question 50

pH of tetracaine

Answer 50

8.5

Question 51

pH of chlorprocaine

Answer 51

9

Question 52

pH of Amide LA

Answer 52

7.6 - 8.1

Question 53

pH of mepivacaine

Answer 53

7.6

Question 54

ph of ropivacaine

Answer 54

8.1

Question 55

Ester LA ⬇️ More Ionization ⬇️ ?

Answer 55

less lipophilic

Question 56

Amide LA ⬇️ 50% ionization ⬇️ ?

Answer 56

more lipophilic

Question 57

onset of action of Ester LA (fastest to slowest)

Answer 57

tetracaine - 8.5 cocaine - 8.7 procaine - 8.9 chlorprocaine - 9

Question 58

onset of action of Amide LA (faster to slowest)

Answer 58

mepivacaine - 7.6 lidocaine - 7.9 prilocaine - 7.9 ropivacaine - 8.1 bupivacaine - 8.1

Question 59

procaine is hydrolyzed by what enzyme?

Answer 59

plasma esterases procaine becomes less stable

Question 60

lidocaine undergoes in what processes in the liver?

Answer 60

oxidation and conjugation lidocaine becomes more stable

Question 61

the ester local anesthetics are hydrolyzed by?

Answer 61

pseudocholinesterases

Question 62

differentiate ester LA and amide LA

Answer 62

basahin mo na lang sa ppt (page 30)

Question 63

Local anesthetics are administered at the?

Answer 63

site of action

Question 64

local anesthetics absorption and distribution from the site of administration reduce the

Answer 64

pharmacologic

Question 65

Absorption of too much local anesthetic may cause

Answer 65

adverse systemic effects

Question 66

Absorption into the blood circulation may be retarded by incorporation of a vasoconstrictor agent such as

Answer 66

epinephrine or phenylephrine

Question 67

Drug is applied to skin and mucous membrane (eyes, nose, mouth, throat, tracheobronchial tree, urinary tract, and gastrointestinal tract) to cause loss of sensory perception.

Answer 67

surface or topical anesthesia

Question 68

application of surface or topical anesthesia on the mucous membrane may lead to

Answer 68

rapid absorption and possible toxicity

Question 69

Most local anesthetic agents are ineffective when applied on unbroken skin because

Answer 69

cornified epithelium limits penetration

Question 70

Surface local anesthetic agents include

Answer 70

cocaine, hexylcaine, lidocaine, tetracaine, and cyclomethylcaine

Question 71

Most commonly used for superficial procedures such as skin biopsy and or suturing wounds the drug is injected directly into skin or deeper structures to facilitate surgery or other painful procedures

Answer 71

infiltration anesthesia

Question 72

Local anesthetics for infiltration anesthesia include

Answer 72

lidocaine, mepivacaine, bupivacaine, etidocaine, and chloroprocaine

Question 73

Drug is injected into the area immediately surrounding the nerve or group of nerves (plexus).

Answer 73

peripheral nerve-block

Question 74

The anesthetic diffuses into the nerve trunks and anesthetize the area innervated by these nerves.

Answer 74

peripheral nerve-block

Question 75

This technique results in the blockade of the sensory, motor, and autonomic pathways

Answer 75

peripheral nerve-block

Question 76

Agents commonly used for peripheral nerve block include:

Answer 76

lidocaine, mepivacaine, and bupivacaine

Question 77

Seldom used in animals

Answer 77

spinal (intrathecal) anesthesia

Question 78

The drug is injected into the CSF of the spinal subarachnoid space.

Answer 78

spinal anesthesia

Question 79

Anesthesia is due to the action of the drug on the spinal nerve roots and in the dorsal root ganglia, thus causing both sensory and motor blockade with rapid onset.

Answer 79

spinal anesthesia

Question 80

Local anesthetics for spinal anesthesia include:

Answer 80

lidocaine (preservative free) and tetracaine

Question 81

Drug is injected into the epidural space of the spinal canal posterior to the end of the spinal cord.

Answer 81

epidural anesthesia

Question 82

It is used in obstetric, perineal; and lower extremity procedures

Answer 82

epidural anesthesia

Question 83

Agents commonly used for epidural anesthesia include

Answer 83

lidocaine, mepivacaine, bupivacaine, etidocaine, and chloroprocaine