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Mikeland
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04/16/07 - 03:23 PM       #1

A patient was administered trimethaphan during surgery. This drug will cause which of the following responses?
A-Accommodation
B-Hypertension
C-Peristalsis
D Pupillary constriction
E- Tachycardia

new_n_lost
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04/17/07 - 05:49 AM       #2

D Pupillary constriction blocks nicotinic receptors

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asherif
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04/17/07 - 07:46 AM       #3

E- Tachycardia (block nicotinic receptors ---> decrease in blood pressure ---> tachycardia)

correct me if I'm wrong

new_n_lost how will blocking nicotinic receptors cause pupillary constriction?

new_n_lost
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04/17/07 - 08:09 AM       #4

it wont cause tachycardia unless its given in high does n the uses of trimethaphan for inducing hypotension esp in aortic dissection where the required BP has to be low so that there isnt a rupture

The ciliary muscle of the eye functions to round the lens for accommodation and is controlled mainly by parasympathetic system input. With administration of a ganglion-blocking drug, the ciliary muscle cannot contract and the patient loses the ability to focus their eyes.


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Mikeland
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04/17/07 - 08:13 AM       #5

Try this, thinking about that Trimethaphan is a ganglionic blocker; and also, what is the predominant tone (sympathetic or parasympathetic). The blocker will produce the oppasite effect of the predominant tone

Mikeland
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04/17/07 - 08:18 AM       #6

The eye is predominantly under parasympathetic control. Parasympathetic stimulation causes the pupil to constrict. If you bock it with Trimethaphan procuce mydriasis. "D" is wrong

asherif
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04/17/07 - 08:26 AM       #7

The ciliary muscle of the eye functions to round the lens for accommodation and is controlled mainly by parasympathetic system input. With administration of a ganglion-blocking drug, the ciliary muscle cannot contract and the patient loses the ability to focus their eyes.


and why would that cause pupillary constriction? ciliray muscle has nothing to do with the iris
and the effect of ganglion blocking agents should actually be midraitic (pupillary dilatation) as the Iris is dominant innervation is parasympathetic.



new_n_lost
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04/17/07 - 08:31 AM       #8

MAn u guys r right then wht shud be the answer then by exculsion the answer shud be E right.

Sorry guys got mixed up. Apologise for it .


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Mikeland
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04/17/07 - 08:33 AM       #9

Asherif you were right, I mentioned before, blocking cause mydriasis, D is wrong. However, What is the tone prdominant in the heart?, knowing this you find the answer. Actualy, you got the aswer, the reason was wrong.

Mikeland
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04/17/07 - 08:33 AM       #10

Right, The predominant tone in heart is parasymphathetic control. Parasymphathetic stimulation of the hearty causes bradycardia. Correct answer is "E"

asherif
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04/17/07 - 09:20 AM       #11

nod yeah that too grin

lq2006
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05/22/07 - 05:09 PM       #12

E

jean robert
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06/01/07 - 12:30 PM       #13

Trimethaphan has a strong effect on the cardiovascular system.

The size of BLOOD VESSELS is primarily controlled by the sympathetic nervous system. Loss of sympathetic system input to the blood vessels causes vasodilation which has the effect of lowering blood pressure.

Effects on the HEART include a decreased force of contraction and an INCREASE IN HEART RATE (TACHYCARDIA)


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