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Flashcards in autonomic nervous system stuff Deck (38):
1

What is the characteristic neuronal layout of the autonomic nervous system?






• Two neuron link between the CNS and the peripheral target organ.
• This isn't like the somatic nervous system
• Preganglionic neurons located in the brainstem or spinal cord connect to postganglionic neurons located in autonomic ganglia outside the CNS
• Postganglionic neurons project to the target organ where they innervate smooth muscle, cardiac muscle, or glands

2

What fibers to the splanchnic nerves carry?

• Preganglionic axons arising from lower 7 thoracic spinal levels

3

Where are the preganglionic neurons of the sympathetic nervous system?

• Located in the intermediolateral column of the thoracic and upper lumbar segments of the spinal cord
• Axons exit from ventral roots of the corresponding spinal nerves

4

Which are myelinated, preganglionic or postganglionic autonomic fibers?

• Preganglionic fibers are myelinated and conduct things faster
• Postganglionic are unmyelinated

5

What do postganglionic autonomic neurons innervate?

• smooth muscle, cardiac muscle, or glands

6

Where do you find acetylcholine released from?






• Preganglionic sympathetic neurons

7

What is the primary work of the sympathetic nervous system?

• Vasodilation and vasoconstriction
• Increased sympathetic tone = vasoconstriction
• Decreased sympathetic tone = vasodilation
• At rest, sympathetic tone keeps the vessels in not-dilated-not-constricted steady state

8

Where are preganglionic sympathetic fibers innervating adrenal medulla found?

• Thoracic levels 6-9

9

What little organ/gland is a specialized component of the sympathetic nervous system?

• Adrenal medulla (adrenal gland)
• Functions as a neuorendocrine gland
• Postganglionic cells contained in adrenal medulla secrete epinephrine (80-90%)and norepinephrine (10-20%) INTO THE BLOODSTREAM
• Adrenergic receptors from far away can then be activated by this system

10

What do postganglionic sympathetic neurons innervate?

• sweat glands, peripheral blood vessels, hair follicles, etc.

11

Where are postganglionic sympathetic neurons found?

• Ganglia of sympathetic trunk (paravertebral chain ganglia)
• Axons from postganglionic neurons exit the spinal trunk through gray rami communicans
• Travel with spinal nerves to reach sweat glands, peripheral blood vessels, hair follicles, etc.

12

Postganglionic sympathetic neurons release what neurotransmitter?

• Norepinephrine

13

Preganglionic sympathetic neurons release what neurotransmitter?

• Acetylcholine
Norepinephrine is found to be released where?
• At the synaptic cleft of postganglionic sympathetic neurons

14

Where are preganglionic neurons of the parasympathetic nervous system located?



• In brainstem nuclei and in sacral spinal cord
• Preganglionic fibers exit the brainstem in CN III, VII, IX, X
• Use acetylcholine as a neurotransmitter
• Innervate postganglionic neurons in ganglia close to/right on top of the effector organ

15

What controls vasodilation?

• It's more the lack of sympathetic input than it is the amount of parasympathetic input

16

Do splanchnic nerves have parasympathetic neurons?

• Yep. The preganglionic parasympathetic neurons travel with the splanchnic nerves out of the sacral level

17

If you see Ach you think…

• Acetylcholine, the neurotransmitter used by the preganglionic fibers of both parasympathetic and sympathetic nervous systems
* also used by postganglionic parasympathetic neurons

18

Postganglionic sympathetic neurons use what NT? Is that different than preganglionic sympathetic neurons?

• Postganglionic sympathetic = norepinephrine
• Preganglionic sympathetic = ach

19

How many types of cholinergic receptors are there?


• Two types
• Nicotinic
• Muscarinic

20

Whare are muscarinic receptors primarily found?

• Muscarinic receptors are present on effector cells (cardiac muscle, smooth muscle, glands)

21

What cholinergic receptors are mainly present in the cell body of postganglionic neurons of the autonomic ganglia?

• Nicotinic receptors
• Muscarinic receptors are present on effector cells (cardiac muscle, smooth muscle, glands)

22

How is the muscarinic receptor's mechanism of action fundamentally different than the nicotinic mechanism of action?

• Nicotinic = non-selective cation channel, ligand gated (ligand binds and the cell will depolarize because lots of ions flow through)
• Muscarinic = GPCR, Gs, increased cAMP and PKA action

23

Epinephrine activates which receptors?

• Adrenergic receptors
• Epinephrine from adrenal medulla activates all 4 suptypes

24

Norepinephrine activates what adrenergic receptors?

• NE only activates alpha1,2 and beta1 (just not beta2)

25

What are the suptypes of adrenergic receptor?

• Subdivided into alpha1,2 and beta1,2 receptors
• NE only activates alpha1,2 and beta1 (just not beta2)
• Epinephrine from adrenal medulla activates all 4 suptypes

26

What makes up adrenergic receptors?

• Adrenergic receptors consist of alpha and beta receptors
• Subdivided into alpha1,2 and beta1,2 receptors
• NE only activates alpha1,2 and beta1 (just not beta2)
• Epinephrine from adrenal medulla activates all 4 suptypes

27

If it's not cholinergic its…

• ADRENERGIC - for epinephrine and norepinephrine

28

The muscarinic receptor in atrial cells does what upon binding Ach?

• Ach from vagus nerve binds to receptor
• G protein opens K channels
• Hyperpolarization and slowing of heart rate is the result

29

How many different subtypes of muscarinic receptor are there?

• 5
• M1 - M5
• Coupled to different proteins and different effector molecules
• Allows Ach to have different effects with same NT

30

What is the example agonist used to bind selectively to alpha1 adrenergic receptors and what does it do?


• Phenylephrine
• Vasoconstriction in skin

31

What is the example agonist used to bind selectively to beta2 adrenergic receptors and what does it do?

• Albuterol
• Increased heart rate
Vasodilation in skeletal muscle

32

What is the example agonist used to bind selectively to beta1 adrenergic receptors and what does it do?

• Dobutamine
• Increased heart rate

33

What is the example agonist used to bind selectively to alpha2 adrenergic receptors and what does it do?

• Clonidine
• Presynaptic inhibition of NE release
• Some vasoconstriction

34

What is the example ANTAGONIST used to bind selectively to alpha1 adrenergic receptors?


• doxazosin

35

What is the example ANTAGONIST used to bind selectively to beta2 adrenergic receptors and what does it do?

butaxamine

36

What is the example ANTAGONIST used to bind selectively to beta1 adrenergic receptors and what does it do?

• atenolol

37

What is the example ANTAGONIST used to bind selectively to alpha2 adrenergic receptors?

• trazodone

38

What is meant when a drug is "sympathomimetic"?

• They activate the sympathetic nervous system stuff