20.8m Blocking & Stimulating Agents

competitive antagonism

Ganglionic blockade is produced by (?) with ACh at the receptors in the autonomic ganglia.

entire autonomic nervous system

This can, in effect, turn off the (?).

trimethaphan

The two medications in this class are (?) (Arfonad) and mecamylamine (Inversine).

hypertension

Both are used to treat (?).

antimuscarinic medications

The adverse effects of ganglionic blockade include signs associated with (?) such as atropine—dry mouth, blurred vision, urinary retention, and tachycardia.

profound hypotension

Other adverse effects arising from the vasodilation and decreased preload caused by sympathetic blockage include (?) with orthostatic hypotension even more evident.

hypertensive crisis

Trimethaphan is administered primarily for (?) when other treatments are ineffective.

selective

These agents are almost never used now because they are not (?) and many superior agents are available.

Neuromuscular blockade

(?) produces a state of paralysis without affecting consciousness.

paralyzed

Imagine how terrifying it would be to be fully conscious and aware but completely (?), unable to move or breathe.

competitive antagonism

Neuromuscular blockade is caused by (?) of receptors at the neuromuscular junction.

electroconvulsive therapy

This is useful during surgery as part of anesthesia and during (?) for depression.

intubation

These agents are most often used in the field to facilitate (?).

depolarizing

Neuromuscular blocking agents are either (?) or nondepolarizing, depending on their mechanism of action.

succinylcholine

Most are nondepolarizing; only one depolarizing medication, (?) (Anectine), is commonly used in the clinical setting.

tubocurarine

Though not frequently used clinically, (?), is the oldest neuromuscular blocker and the prototype nondepolarizing agent.

muscle depolarization

It produces neuromuscular blockade by binding with the receptor sites without causing (?).

Succinylcholine

(?) acts in the same manner, but like ACh, it does cause muscle depolarization when it binds with the receptor.

repolarization

It is useful as a neuromuscular blocker because, in contrast to ACh, which rapidly separates from the receptor, it remains bound, preventing the muscle’s (?).

rate of onset

Several nondepolarizing agents are available; the specific agent chosen depends on its (?) and duration of action.

pseudocholinesterase

Succinylcholine has the shortest onset and duration of action because it has a naturally occurring enzyme, (?), which degrades it.

Table 20-16

See (?).

Nicotinic-N receptors

(?) reside at the ganglia of both the parasympathetic and sympathetic nervous systems.

nicotine

The alkaloid (?) stimulates these receptors.

tobacco

Nicotine is found in (?) and, although it has no therapeutic uses, is of interest for two reasons.

Historically

Historically, nicotine, along with muscarine, led to a much better understanding of the autonomic nervous system’s specific receptors.

abused medications

Also, it is one of the most (?) in the world.

dose related

Nicotine can cause a variety of responses, most of which are (?).

low doses

At (?), similar to those from smoking, nicotine causes excitation at the autonomic ganglia.

parasympathetic and sympathetic nervous systems

This affects both the (?) .

parasympathetic response

The (?) causes increased salivation, peristalsis, and secretion of gastric acid.

sympathetic response

The (?) causes the release of norepinephrine and epinephrine.

heart’s workload

These lead to increases in heart rate, myocardial contractility, vasoconstriction, and blood pressure, all of which increase the (?).

awareness

Sympathetic stimulation also increases (?) and suppresses fatigue and appetite.

smoking cessation

Nicotine administration devices such as gum and transdermal patches are available for use in (?).

nicotine inhaled in smoking

Their actions are similar to those of (?).