Autonomic Nervous System

Question 1

2 divisions of the ANS

Answer 1

sympathetic

parasympathetic

Question 2

Both systems are (3)

Answer 2

Involuntary, Excitatory & Inhibitory, Di-synaptic

Question 3

Generally — one another when they innervate the same tissue.

Answer 3

oppose

Question 4

Each system is — active, but one system is usually

predominant at rest.

Answer 4

tonically

Question 5

Sympathetic (SNS) (3)

Answer 5

• Fight or Flight
• Can selectively activate 
effectors or elicit a mass 
discharge, especially 
during stress response
• Noraderenergic 
(NE)/Adrenergic (EPI)
– BUT cholinergic pre- to 
post-ganglionic

Question 6

Parasympathetic (PNS) (3)

Answer 6

• Rest & Digest
• Control mechanisms are 
almost always specific, 
activating or inhibiting 
discrete targets.
• Cholinergic (ACH)

Question 7

Both the SNS & PNS have: (2)

Answer 7

Preganglionic neurons

Postganglionic neurons

Question 8

Preganglionic neurons (cell 
bodies in

Answer 8

lateral gray horn of the
spinal cord (SNS) or motor nuclei
of cranial nerves III, VII, IX and X
(PNS))

Question 9

All preganglionic terminals

release

Answer 9

ACh that binds to
nicotinic receptors (Type NN)
on the postganglionic neuron

Question 10

— receptors are ligand-
gated ion channels (ionotropic)
that are selective for both (2)

Answer 10

nACh
Na+
and K+.

Question 11

Postganglionic neurons cell

bodies are

Answer 11

outside of the CNS

Question 12

Thoracolumbar Division

Answer 12

T1 through L3 or L4

Question 13

Preganglionic axons exit through a white ramus into one of

the ganglia of the sympathetic chain. Fibers will then either: (4)

Answer 13

1. Synapse with postganglionic 
neurons at that ganglia
2. Pass up or down the 
sympathetic chain, then 
synapse with a different 
ganglia
3. Pass through the chain and 
out a sympathetic nerve 
(Splanchnic) where it will 
synapse in a peripheral 
sympathetic ganglion (celiac, 
superior mesenteric, or 
inferior mesenteric)
4. EXCEPTION:  Adrenal 
Medulla

Question 14

Almost all sympathetic postganglionic terminals release

— which —

Answer 14

norepinephrine (NE/noradrenaline) at synapse with target cells.
NE activates both alpha and beta receptors.

Question 15

Almost all sympathetic postganglionic terminals release
norepinephrine (NE/noradrenaline) at synapse with target cells.
NE activates both alpha and beta receptors.
– Exception:

Answer 15

most sympathetic post-ganglionic terminals release ACh
at sweat glands to activate muscarinic receptors. Some skeletal
muscle vasculature also works this way.

Question 16

When stimulated, the adrenal medulla (chromaffin cells)

secretes

Answer 16

80% epinephrine (EPI/adrenaline) and 20% NE into
the bloodstream. EPI and NE then circulate throughout the
body and activate adrenergic receptors.

Question 17

The adrenal medulla contains the enzyme —, which catalyzes the conversion of NE to
EPI (this reaction requires cortisol)

Answer 17

phenylethanolamine-N-

methyltransferase (PNMT)

Question 18

Compared to beta receptors, alpha receptors have a –

affinity for catecholamines, so beta receptors are activated at

Answer 18

lower
lower concentrations (i.e. beta receptors have a higher affinity)

Question 19

Norepinephrine has a slightly greater potency at —

receptors compared to epinephrine.

Answer 19

alpha

Question 20

Alpha 1:

Answer 20

constrict smooth muscle (Gq protein, increase IP3)

Question 21

Alpha 2:

Answer 21

blocks further NE release (presynaptic receptor) (Gi

protein, decrease cAMP)

Question 22

Catecholamine Potency for Beta receptors varies: (3)

Answer 22

Epi & NE have almost equal potency at beta 1 receptors;
Epi has MUCH greater potency at beta 2 receptors than NE;
NE has slightly greater potency at beta 3 receptors than EPI.

Question 23

Beta 1:

Answer 23

increase heart rate & contractility, increase lipolysis, increase
renin secretion, increase protein content in saliva (Gs
protein: increase cAMP)

Question 24

Beta 2:

Answer 24

relax smooth muscle, release FA & glucose (Gs protein: increase
cAMP)

Question 25

Beta 3:

Answer 25

found in adipose tissue (Gs protein: increase cAMP)

Question 26

Systemic absorption of injected local anesthetics depends on

Answer 26

blood flow to the area.

Question 27

The addition of epinephrine causes

Answer 27

vasoconstriction (via alpha 1 receptors) at the site of administration, which decreases blood absorption and facilitates neuronal uptake, enhances quality of analgesia, prolongs duration of action and limits toxic side effects. Addition of EPI to lidocaine usually extends the duration of anesthesia by at least 50%.

Question 28

Albuterol

Answer 28

Beta 2 selective agonist, is used for treatment of asthma | as it causes bronchodilation.

Question 29

NE that is released by nerve terminals remains active for only a few seconds before: (3)

Answer 29

1. Diffusion away from synaptic cleft 2. Reuptake by presynaptic terminal (cocaine blocks re-uptake) 3. Destruction by the enzymes MonoAmine Oxidase (MAO) or Catechol-O-Methyl Transferase (COMT)

Question 30

PNS compared to SNS: (2)

Answer 30

``` – PNS has longer preganglionic axons than SNS. – Preganglionic terminals also release ACh that binds to nicotinic ACh receptors. ```

Question 31

Craniosacral Division (2)

Answer 31

``` – Preganglionic parasympathetic axons supply the face via the oculomotor (III), facial (VII), glossopharyngeal (IX) nerves and the thorax and upper abdomen via the vagus (X) nerve. – S2-4 carry preganglionic parasympathetic axons to the pelvic viscera. ```

Question 32

Postganglionic parasympathetic varicosities release

Answer 32

ACh that bind | to muscarinic ACh receptors on target cells.

Question 33

Muscarinic receptors (G-protein/metabotropic) (3)

Answer 33

– Constrict smooth muscle – Relax sphincters – Stimulate glandular secretions

Question 34

Known Muscarinic Receptors (4)

Answer 34

– M1 – M2 – M3 – M4

Question 35

– M1:

Answer 35

stomach (secretions and contraction), salivary glands (Gq: IP3, increase IC Ca++)

Question 36

– M2:

Answer 36

smooth muscle, myocardium, cardiac autorhythmic cells, CNS (Gi protein, decrease cAMP)

Question 37

– M3:

Answer 37

exocrine glands (ex. salivary), smooth muscle, endothelium, CNS (Gq: IP3, increase IC Ca++)

Question 38

– M4:

Answer 38

CNS, vagal nerve (Gi protein, decrease cAMP)

Question 39

Cholinergic Receptors (5)

Answer 39

``` – M1 – M2 – M3 – M4 _ M5 ```

Question 40

M5:

Answer 40

sweat glands (SYMPATHETIC FUNCTION) (Gq: IP3, increase IC Ca++)

Question 41

Anticholinergic drugs such as amitriptyline (Elavil), a | tricyclic antidepressant, inhibit the effects of

Answer 41

``` acetylcholine systemically (via muscarinic receptors), resulting in a myriad of side effects. Gastrointestinal side effects include xerostomia, constipation, ileus, and nausea and vomiting. ```

Question 42

• Sialorrhea (drooling) can occur in patients taking

Answer 42

anti-cholinesterases (ex. treatment for Alzheimer’s Disease).

Question 43

Skeletal Muscle: Binding of ACh to NM receptor elicits

Answer 43

contraction

Question 44

Relaxation occurs when

Answer 44

ACh release by the somatic motor neuron and activation of NM receptor stops

Question 45

PNS: bladder (2)

Answer 45

M2 Relax sphincter | M3 Constricts detrusor

Question 46

SNS: bladder (2)

Answer 46

alpha1 Constricts sphincter | beta2 Relaxes detrusor

Question 47

PNS: GI Tract (2)

Answer 47

M2 Relax sphincter | M3 Contracts muscle

Question 48

SNS: GI Tract (2)

Answer 48

alpha1 Constricts sphincter | beta2 Relaxes muscle

Question 49

PNS :Salivary Glands

Answer 49

``` M1 and M3 Stimulates lots of watery secretion due to contraction of myoepithelial cells and vasodilation ```

Question 50

SNS: Salivary Glands (2)

Answer 50

alpha1 vasoconstriction and secretion of concentrated saliva beta1 receptors stimulate secretion of protein

Question 51

anti-cholinergic drugs for the treatment of Parkinson’s Disease can cause

Answer 51

Xerostomia

Question 52

``` Methamphetamine acts on the α -adrenergic receptors of the vasculature of the salivary glands, causing vasoconstriction and reducing salivary flow, depriving the oral environment of saliva's buffering activity to counteract acidity and prevent demineralization of enamel leading to ```

Answer 52

“Meth Mouth”.

Question 53

PNS: vascular smooth muscle/blood

Answer 53

NA

Question 54

SNS: vascular smooth muscle/blood

Answer 54

alpha1 vasoconstriction beta2 vasodilation

Question 55

the diameter of most arterioles in the body is not regulated by the PNS, but there are a few exceptions. For example, the PNS (via ACH on Muscarinic Receptors) causes

Answer 55

vasodilation of salivary gland arterioles, which increases blood flow to the salivary glands for secretion of saliva. A few other arterioles that dilate under PNS control include arterioles of the gastric and intestinal glands.

Question 56

PNS: Heart

Answer 56

Keeps HR low (M2)

Question 57

SNS: heart

Answer 57

increases HR and contractility (beta 1) and coronary blood flow via vasodilation (beta 2)

Question 58

PNS: lungs

Answer 58

predominant tone | constricts bronchial smooth muscle (M3)

Question 59

SNS: lungs

Answer 59

relaxes bronchial smooth muscle (beta2)