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Pharm Block 10 > Cholinergic Agonisits > Flashcards

Cholinergic Agonisits Flashcards

1
Q

What is the rate limiting step of ACH synthesis

A

Choline uptake

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2
Q

Release of Ach

A
  • membrane depolarizes
  • open Ca2+ channels and Ca2+ rushes in
  • this causes the vesicles to move to the membrane and release Ach into the synapse
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3
Q

What are the 3 fates of ACH once it is in the synapse?

A
  1. Binds postsynaptic receptor
  2. Metabolized by acetylcholinesterase
  3. Ach binds to presynaptic nerve (same nerve that releases)
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4
Q

What does Ach bind to postsynaptically

A

Nicotinic or muscarinic receptors

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5
Q

How is Ach metabolized

A

By acetylcholinesterase

-breaks it into choline and esterase

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6
Q

What happens to the choline once acetylcholinesterase has metabolized Ach

A

It gets recycled, it never takes in whole Ach, has to be choline

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7
Q

Why does Ach have a short half life

A

Because acetylcholinesterase metabolizes it so quickly

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8
Q

What happens when Ach binds to the presynaptic cleft?

A
  • regulation by negative feedback
  • usually an M2 receptor (GI)
  • decreases CAMP, which decreases Ca2+ channels opening, which stops Ach release.
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9
Q

All NT releasing neurons have to be regulated by

A

Negative feedback

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10
Q

What receptors do NE bind to regulate with negative feedback

A

A2

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11
Q

What receptors do dopamine have to bind to to regulate via negative feedback

A

D2

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12
Q

What does an acetylcholinesterase inhibitor act like

A

Muscarinic agonist

Increases the half life of Ach

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13
Q

What does Botox do to the release of Ach

A

Decreases it

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14
Q

What does Botox do to a somatic muscle nerve

A

Muscle wont contract,relaxes it

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15
Q

Botox and sweat glands

A

Inject into sweat glands to decrease sweat, sweat is activated by Ach

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16
Q

What does spider venom do to Ach

A

Causes very increased released of Ach

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17
Q

Can bind acetylcholine and the alkaloid muscarine

A

Muscarinic receptors

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18
Q

What are the subclasses of muscarinic receptors

A

M1,M2,M3,M4,M5

We dont talk much anoint 4 and 5

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19
Q

M1 receptors located mainly in the

A

CNS

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20
Q

M2 receptors mainly located in the

A

Heart and presynaptic preganglionic nerves

21
Q

Where are M3 receptors found

A

Just about everywhere except the heart and CNS

22
Q

Properties of muscarinic receptor agonists

A
  • show selectivity for muscarinic receptors
  • mimic the actions of Ach but have longer 1/2 life
  • parasympathetic effects + sweating (symp)
23
Q

Muscarinic receptor agonist drugs

A
  • bethanechol
  • carbachol
  • methacholine
  • pilocarpine
  • cevimeline
24
Q

GI system effects of muscarinic agonists

A

-stimulates the GI tract
Increases just about everything
-may be accompanied by nausea, belching, vomiting, intestinal cramps, and defacation

25
Q

Urinary effects of muscarinic agonists

A

Increased urination

  • increase ureteral peristalsis
  • contract dertusor muscle
  • relax the trigone and sphincter muscle
  • increase max voluntary voiding pressure
  • decrease capacity of the bladder
26
Q

Muscarinic receptors in urinary tract

A

M3

27
Q

Muscarinic receptors in the GI Tract

A

M3

28
Q

Cardiovascular effects of a muscarinic agonist

A

M2
-decrease HR, contractility, and rate of conduction

M3
-vasodilation with drugs only

29
Q

M3 receptors in the blood vessels

A
  • physiologically inactive
  • pharmacologically useful
  • there are 3 receptors in BV, a1, b2, m3
  • a1 is innervated and activated by epi and b2 is activated by epi from adrenal medulla
  • m3 has no nerve and does not get Ach from any other source.
  • can only be activated pharmacologically
  • releases NO onto smooth muscles to cause vasodilation
  • activated by muscarinic agonist
30
Q

Miscellaneous effects of muscarinic agonists

A

Increased secretions
Bronchoconstriction
Miosis and accommodation

31
Q

Why are acetylcholine and carbachol not good for the GI tract

A

They are not very selective and will also bind nicotinic receptors

32
Q

Used to stimulate the smooth muscle of the GI tract and bladder. Used for urinary retention and gastric atony

A

Bethanechol

“Bowels and bladder”

33
Q

Carbachol and decreasing IOP

A

Used to decreased IOP, but it is as last choice drug for that.

34
Q

Why is carbachol’s use restricted

A

Because of nicotinic effects at autonomic ganglia. Rarely used because it is not selective enough

35
Q

What is methacholine important for

A

Helps dx asthma

  • causes bronchoconstriction
  • can dx astham in subjects who do not have clinically apparent asthma (methacholine chllange test)
  • asthma patients more sensitive to this
36
Q

Pilocarpine and glaucoma

A

Used for open angle glaucoma and angle closure glaucoma. Not first choice. Low priority

37
Q

What are pilocarpine and cevimeline important for

A

Xerostomia

  • occurs after head and neck radiation tx or with sjogrens sysndrom.
  • stimulates salivary secretions which eases swallowing
38
Q

What is a drug you would give to someone who is having difficulty swallowing due to a dry mouth

A

Pilocarpine or cevimeline

39
Q

This is an autoimmune disease causing decreased secretion (dryness)

A

Sjogren’s

40
Q

What does glaucoma treatment usually involve

A

Decreased the production or increased the drainage of aqueous humor
-muscarinic agonists increase fluid drainage

41
Q

Toxicity of muscarinic agonists

A

Miosis, bradycardia, bronchoconsitrion (dont give to asthma patients), increased gastric acid production (avoid in ulcers), diarrhea, increased ruination, flushing, salivation, lacrimation, sweating

42
Q

How are muscarinic agonists given to avoid toxicity

A

Topically

43
Q

What is given to treat serious toxic reactions to muscarinic agonists

A

Atropine sulfate or epinephrine

44
Q

What kind of binding is atropine sulfate in the case of a muscarinic agonist overdose

A

Pharmacological

45
Q

What kind of binding is epinephrine in the case of a muscarinic agonist overdose

A

Physiologic

Binding symp receptors while the agonist is binding parasympathetic

46
Q

Why is reversible drugs more therapeutic than nonreversible

A

Because they are less dangerous

They have temporary inhibition, binds and lets go

47
Q

This group of drugs inhibits achase

A

Acetylcholinesterase inhibitors

48
Q

How can acetylcholinesterase inhibitors be exerted

A

At either nicotinic or muscarinic receptors

Pharm Block 10 (6 decks)

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