Chapter 16 - Drugs that block nicotinic cholinergic transmission

Question 1

Neuromuscular blocking agents prevent acetylcholine from activating ________ receptors on skeletal muscles causing ______

Answer 1

Nicotinic M ; muscle relaxation

Question 2

Why are neuromuscular blocking agents given?

Answer 2

produce muscle relaxation during surgery, intubation, ventilation and other procedures

Question 3

What are the two major catagories of neuromuscular blockers?

Answer 3

1. Competitive (nondepolarizing)

2. depolarizing agents

Question 4

What is excitation-contraction coupling?

Answer 4

process by which an action potential in a motor neuron leads to contraction of a muscle

Question 5

In _______ muscle there is uneven distribution of electrical charge across the inner and outer surfaces of the cell membrane.

Answer 5

resting

Question 6

Because of the uneven charge distributioni in a resting muscle the resting membrane is said to be _______

Answer 6

polarized

Question 7

What happens when the membrane depolarizes?

Answer 7

positive charges move from outside to inside

Question 8

Repolarization?

Answer 8

by pumping positively charged ions out of the cell

Question 9

_______ restores the original resting membrane state, with positive charges on the outer surface and negative charges on the inner surface.

Answer 9

repolarization

Question 10

What causes the muscles to relax?

Answer 10

because there is no longer any calcium available to support the interaction of actin and myosin

Question 11

Competitive neuromuscular blocking agents are drugs that compete with acetylcholine for binding

Answer 11

nicotinic M receptors (also known as nondepolarizing neuromuscular blockers)

Question 12

______ is one of several active principles found in curare, an arrow poison.

Answer 12

Tubocurarine

Question 13

The clinical utility of the neuromuscular blockers is based on the same action that is useful in hunting

Answer 13

production of skeletal muscle relaxation

Question 14

All of the neuromuscular blocking agents contain at least one ________

Answer 14

quanternary nitorgen. As a result these drugs always carry a positive charge, and can not readily cross membranes.

Question 15

The inability of neuromuscular blockers to cross membranes has what three clinical consequences ?

Answer 15

1. must be given IV bc they are not absorbed by GI Tract
2. Cannot cross blood brain barrier
3. cannot readily cross the placenta

Question 16

Muscle function can be restored by eliminating the drug or by increasing the amount of _______ at the neuromuscular junctions

Answer 16

acetylcholine

Question 17

The primary effect of neuromuscular blockers is relaxation of skeletal muscle, causing a state known as _____

Answer 17

flaccid paralysis

Question 18

What are the first drugs to be paralyzed when using neuromuscular blockers?

Answer 18

levator muscle of the eyelid and the muscles of mastication

last muscles affected are muscles of respiration-the intercostals and diaphragm

Question 19

Histamine lowers blood pressure by causing _____

Answer 19

vasodialation

Question 20

paralysis peaks in ____ minutes and complete recover takes _____

Answer 20

20-45 ; one hour

Question 21

Which neuromuscular blocker releases significant amounts of histamine causing hypotension?

Answer 21

atracurium

Question 22

Neuromuscular blocking agents must be used with special care in patients with

Answer 22

myasthenia gravis (bc muscles are already weak)

Question 23

low potassium levels can _____ paralysis, whereas high potassium levels can _____ paralysis.

Answer 23

enhance ; reduce

Question 24

What ABX can intensify responses to nerumuscular blockers?

Answer 24

aminogylcosides(gent), tetracyclines and nonpenicillin ABX

Question 25

Cholinesterase _______acetylcholine

Answer 25

degrades (breaks down)

Question 26

cholinesterase inhibitors increase responses to _______,

Answer 26

succinylcholine

Question 27

What is succinylcholine?

Answer 27

a depolarizing neuromuscular blocker

Question 28

If a neuromuscular blocker dose is to high, what drug will be given?

Answer 28

neostigime. Need to give a cholinesterase inhibitor.

Question 29

Resp depression can be reversed by using a ________

Answer 29

cholinesterase inhibitor

Question 30

What is the only depolarizing neuromuscluar blocker in clinical use?

Answer 30

succinylcholine [anectine, quelicin]

Question 31

What are the two differences of depolarization neuromuscular blockers from competitive neuromuscular blockers?

Answer 31

1. paaralysis from succinylcholine is preceded by transient contractions 2. paralysis abates more rapidly due to it being rapidly degraded by pseudocholinesterase, an enzyme in the plasma

Question 32

Succinylcholine is used for what type of procedures?

Answer 32

intubation. Because of brief duration

Question 33

Malignant hyperthermia is a rare and potentially fatal condition that can be triggered by

Answer 33

succinycholinel

Question 34

Malignant hyperthermia s/s

Answer 34

muscle rigidity associated with a profound elevation of body temperature—sometimes as high as 43°C. Temperature becomes elevated owing to excessive and uncontrolled metabolic activity in muscle, secondary to increased release of calcium from the SR. Can also cause dysrhythmias, unstable blood pressure, electrolyte problems and metabolic acidosis.

Question 35

Succinylcholine promotes release of _____ from tissues

Answer 35

potassium

Question 36

What drugs potentiate the effects of succinycholine?

Answer 36

cholinesterase inhibitors. They decrease the activity of pseudocholinesterase