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Physiology II Final > Lecture 19: Autonomic Nervous System > Flashcards

Lecture 19: Autonomic Nervous System Flashcards

1
Q

What can the ANS control in general?

A

Visceral function rapidly and intensely

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2
Q

The ANS pathways typically consists of what two neurons in sequence?

A

Preganglionic neuron and postganglionic neuron

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3
Q

Describe preganglionic neurons

A

Cell bodies are located within CNS
Axons are myelinated
Neurotransmitter is ACH

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4
Q

Describe postganglionic neuron

A

Cell bodies are located in peripheral ganglia
Axons unmyelinated
Neurotransmitter is ACH (parasym) or norepinephrine (symp)

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5
Q

How does the ANS generally transmit its effector functions to the organs they innervate?

A

Its like a cloud of neurotransmitters released to the general area. Dont form complex releationships with effector structures.
Most parasympathetic and almost all sympathetic postganglionic fibers merely touch or pass near to the effector cells. Terminal ends of these fibers usually have enlarged varicosities where neurotransmitter and large numbers of mitochondria are stored.

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6
Q

Where does the cell body of each sympathetic preganglionic neuron lie?

A

In the intermediolateral horn of the spinal cord

Thoracolumbar (T1-L2)

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7
Q

(sympathetics) Preganglionic fibers can synapse with postganglionic neurons upward or downward in what?

A

The paravertebral chain

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8
Q

Preganglionic fibers can pass for variable distances through the paravertebral chain and then through one of the sympathetic nerves to synapse where?

A

in the peripheral sympathetic ganglion

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9
Q

Describe postganglionic sympathetic fibers

A

Pass through the gray rami
Type C fibers
Make up about 8% of the fibers in the average nerve
Control blood vessels, sweat glands, piloerector muscles

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10
Q

Describe secretory cells of the adrenal medulla

A

They are modified postganglionic neurons that have rudimentary fibers that secrete epinephrine and norepinephrine

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11
Q

What stimulates the adrenal medullae?

A

sympathetic system

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12
Q

How much epinephrine and norepinephrine do the adrenal medullae secrete?

A

80% epinephrine

20% norepinephrine

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13
Q

Do hormones or neurotransmitters last longer?

A

Hormones last 5-10 times longer

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14
Q

What does circulating norepinephrine do?

A

Constricts most of the blood vessels of the body
Greater effect on raising arterial pressure
Increases heart activity
Inhibits GI tract
Dilates pupil

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15
Q

What effect does circulating epinephrine have on the body?

A

Raises arterial pressure to a lesser extent than norepinephrine
Increases cardiac output MORE than norepinephrine
has a 5-10 times as great effect on metabolism as norepinephrine
Can increase metabolic rate of whole body by as much as 100% above normal

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16
Q

What occurs during a fright or flight response?

A 
Increased arterial pressure
Rerouting of blood flow to active muscles
Increased rates in cellular metabolism
Increased blood glucose concentration
Increased glycolysis in liver and muscle
Increased muscle strength 
Increased mental activity 
Increased blood coagulation rate
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17
Q

About 75% of all parasympathetic fibers are in what?

A

The vagus nerve

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18
Q

Most parasympathetic preganglionic fibers pass all the way to what?

A

To the organ that is to be innervated

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19
Q

Describe postganglionic parasympathetic fibers

A

Located in the wall of the organ

Use Ach as their neurotransmitter

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20
Q

How is acetylcholine made?

A

Acetyl-CoA + Choline -> acetylcholine

choline acetyl-transferase

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21
Q

How is acetylcholine broken down?

A

By acetylcholinesterase

Breaks down into choline + acetate ion

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22
Q

How is norepinephrine synthesized?

A

Hydroxylation of tyrosine to dopa
Decarboxylation of dopa to dopamine
Transport of dopamine into vesicles
Hydroxylation of dopamine to norepinephrine

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23
Q

How does 80% of norepinephrine in the adrenal medulla form epinephrine?

A

It is methylated to form epinephrine

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24
Q

How is norepinephrine removed?

A

Reuptake
Diffusion
Destruction by monamine oxidase (found in nerve endings)
Destruction by catechol-O-methyl transferase (present in all tissues) COMT

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25
Q

How long does norepinephrine/epinephrine active when secreted directly into the tissues?

A

For only a few seconds

26
Q

How long does norepinephrine/epinephrine active when secreted into the blood via the adrenal medulla?

A

It remains active until destroyed by COMT in surrounding tissues, especially liver

27
Q

What is muscarinic?

A

acetylcholine receptors are found on all effector cells stimulated by postganglionic cholinergic neurons

28
Q

Where are nicotinic receptors found?

A

Acetylcholine receptors found in autonomic ganglia at synapses between preganglionic and postganglionic neurons
Present in neuromuscular junctions in skeletal muscels

29
Q

Norepinephrine excites mainly what type of receptors?

A

Mainly alpha receptors but also beta receptors to a lesser extent

30
Q

Epinephrine excites what types of receptors?

A

Both alpha and beta equally

31
Q

Are alpha receptors excitatory?

A

Cetain alpha receptors are excitatory; others inhibitory

32
Q

Alpha receptors are associated with what functions?

A 
Vasoconstriction
Iris dilation
Intestinal relaxation
Intestinal sphincter contraction
Pilomotor contraction 
Bladder sphincter contraction
Inhibition of neurotransmitter release
33
Q

What are beta 1 adrenergic receptors associated with?

A

Cardioacceleration
Increased myocardial strength
Lipolysis

34
Q

What are beta 2 adrenergic receptors associated with?

A 
Vasodilation
INtestinal relaxation
Uterus relaxation
Bronchodilation
Calorigenesis
Glycogenolysis 
Bladder wall relaxation
35
Q

What are nicotinic receptors?

A 
Cholinergic receptors (acetylcholine receptors) that respond to both ACh and nicotine
They are ionotropic receptors - or - ligand-gated ion channels
36
Q

What are muscarinic acetylcholine receptors?

A

Responsive to ACh and muscarine

Metabotropic receptors or G protein-coupled receptors

37
Q

What are beta3 adrenergic receptors associated with?

A

thermogenesis

38
Q

Phenylephrine drug effects what receptor?

A

Alpha

39
Q

Isoproterenol drug effects what receptor?

A

beta receptors

40
Q

Albuterol drug effects what receptor?

A

beta2

41
Q

What is ephedrine used for

A

Sympathomimetic amine
Used as a stimulant, concentration aid, decongestant, appetite suppressant, and to treat hypotension associated with anaesthesia

42
Q

What is tyramine?

A

Acts as a catecholamine releasing agent

43
Q

What is amphetamine

A

Potent CNS stimulant used in the treatment of attention deficit hyperactivity disorder and narcolepsy

44
Q

What does reserpine do?

A

Blocks synthesis and storage of norepinephrine

45
Q

What does guanethidine do?

A

Blocks release of norepinephrine

46
Q

What does phenoxybenzamine/phentolamine do?

A

Blocks sympathetic alpha receptors

47
Q

What does propranolol do?

A

Blocks sympathetic beta1 and beta2 receptors

48
Q

What does metoprolol do?

A

Blocks mostly sympathetic beta1 receptors

49
Q

What does hexamethonium do?

A

Blocks transmission through autonomic ganglia

50
Q

Describe parasympathomimetic drugs

A

Not rapidly destroyed by cholinesterase
Include pilocarpine and methacholine
Act directly on muscarinic receptors

51
Q

What are some drugs that inhibit acetylchoninesterase?

A

Neostimmine
Pyridostigmine
Ambenonium

52
Q

What are some drugs that block cholinergic activity?

A

Atropine
Homatropine
Scopolamine

53
Q

What effects does the ANShave on eyes?

A

Sym: pupil dilation
Para: pupil constriction; lens focusing

54
Q

What effects does Sympathetics have on glands?

A

Causes secretion of large amounts of sweat:
Cholinergic except hands and feet
Actually a parasympathetic function distributed via sympathetic fibers

55
Q

What effects does parasympathetics have on glands?

A

Strongly stimulates lacrimal, nasal, salivary and many GI glands
Strongly stimulates GI glands of upper tract

56
Q

What effects does sympathetics have on GI tract?

A

Strong stimulation inhibits peristalsis

GI tract is normally not dependent on sympathetic stimulation

57
Q

What effects does parasympathetics have on GI tract?

A

Promotes peristalsis

Relaxes sphincters

58
Q

What effects does parasympathetics have on blood vessels?

A

Almost no effect

59
Q

What effect does ANS stimulation have on arterial pressure?

A

Sym: results in acute increase in arterial pressure but little effect long term
Para: decreases pumping of heart but little effect on blood pressure

60
Q

Describe ANS effects on endodermal structures

A

Sym: inhibits
Para: excites

Physiology II Final (4 decks)

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