Autonomics 3 Flashcards

1
Q

What type of receptor do preganglionic parasympathetic fibers synapse on?

A

nicotinic

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2
Q

What type of receptor do postgangilonic parasympathetic fibers synapse on?

A

muscarinic receptors

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3
Q

Two Types of Cholinergic Receptors

A
  1. Nicotinic
  2. Muscarinic
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4
Q

Describe the path of ACh in the synapse.

A
  1. Aceytlcholine made in presynaptic neuron from choline and acetyl CoA
  2. Released from a vesicle into the synapse
  3. Some ACh will bind to receptors, other will be broken down by acetylcholinesterase
  4. Choline transported back into axon terminal to make more ACh
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5
Q

Are nicotinic receptors always excitatory?

A

yes

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6
Q

What type of receptor is a nicotinic receptor?

A

ligand-gated ion channel (ACh binds and causes channel to open, Na+ rushes in and membrane depolarizes)

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7
Q

What type of receptor will you find in neuromuscular junctions?

A

nicotinic

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8
Q

Nicotine

A

mimics ACh at nicotinic receptors

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9
Q

How many types of muscarinic receptors are there?

A

five (5)

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10
Q

Muscarine

A

mimics ACh at muscarinic receptors; water-soluble toxin derived from a mushroom

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11
Q

Are muscarinic receptors always excitatory?

A

NO, they can be excitatory or inhibitory, depending on type and where it binds

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12
Q

What are muscarinic receptors bound to?

A

G-proteins, and second messenger systems (therefore slower acting and more local)

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13
Q

Gq

A

excitatory G protein

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14
Q

Gi

A

inhibitory G protein

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15
Q

Which muscarinic receptors are excitatory?

A

M1, M3, and M5

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16
Q

Which muscarinc receptors are inhibitory?

A

M2, M4

17
Q

What parasympathetic muscarinic receptor is found in the heart?

A

M2

18
Q

What parasympathetic muscarinic receptor is found in arteries, veins, eyes, lungs, GI tract, urinary system, and salivary glands?

A

M3

19
Q

Parasympathetic System Effect on Bladder

A

contract the detrusor muscles (promote urine)

20
Q

Parasympathetic System Effect on Stomach and Intestines

A

increase gastric acid secretion, contract smooth muscle and increase motility

21
Q

Parasympathetic System Effect on Heart

A

decrease heart rate and blood pressure

22
Q

Parasympathetic Effect on Arteries and Veins

A

vasodilation, decrease blood pressure

23
Q

Parasympathetic System Effect on Bronchioles

A

bronchial contraction

24
Q

Parasympathetic System Effect on Eyes

A

contraction of pupil due to relaxation of the CIRCULAR msucles of the iris

25
Q

Asthma and the Parasympathetic System

A

relaxing means bronchioles contract, therefore breathing difficulty increases leading to coughing at night

26
Q

Does the parasympathetic system have any effect on bladder or intestinal sphincters?

A

no, sphincters are only affected by the sympathetic nervous system (a1 contraction)

27
Q

Which two receptors are never located in the same region? Why?

A

a1 and M3 - two dfferent systems but the same contracting function

28
Q

In what special case will M3 have no contracting function?

A

arteries (blood vessels)

M3 will act on endothelial cells and trigger nitric oxide synthesis which binds to something in smooth muscle to make cGMP which reduces calcium and therefore relaxes the smooth muscle cells

29
Q

Direct Acting cholinergic agonists

A

act on muscarinic receptors to activate a tissue response

30
Q

Pilocarpine

A

cholinergic agent used to treat glaucoma by constricting the pupil by stimulating M receptor with minimal effect on N receptor

31
Q

SLUD effect

A

salivation, lacrimation, urination, defecation

32
Q

Indirect Acting Cholinergic agonists

A

inhibit acetylcholinesterase

33
Q

2 Types of Indirect Acting Cholinergic agonists

A
  1. Reversible Inhibitors
  2. Irreversible Inhibitors
34
Q

Can cholinergic agonists pass the blood brain barrier?

A

some of them

35
Q

Should you ever use an organophospahte as medicine?

A

NO!

It is used in pesticides and nerve gasses!

36
Q

Anticholinergics

A

inhibit muscarinic ACh receptors and allow sympathetic system to take over

37
Q

Ganglionic receptor agonists

A

block both sympathetic and parasympathetic transmission of nerve impulses (act on nicotinic receptors)

38
Q

Why don’t we use ganglionic receptor agonists in vet med?

A

because they are not selective