The Autonomic Nervous System

Question 1

Regulates the function of smooth muscle and cardiac muscle and also controls some aspects of metabolism

-involuntary

Answer 1

Autonomic Nervous System (ANS)

Question 2

The ANS is centrally regulated by nuclei in the

Answer 2

Medulla, Pons, Hypothalamus, and Spinal cord

Question 3

Some examples of tissues that are modulated by the ANS include

Answer 3

Cardiovascular, renal, GI, and Endocrine

Question 4

Afferent tracts that affect the ANS are classified as

Answer 4

1. ) Visceral afferents
2. ) Somatic Afferents
3. ) Central chemo afferents
4. ) Cognitive components of CNS

Question 5

Information regarding anger, arousal, stress, etc

Answer 5

Cognitive components of the CNS

Question 6

Designed for coping with acute challenges such as elevations in heart rate and blood pressure

Answer 6

Sympathetic nervous system (SNS)

Question 7

Very active during resting conditions and chronically regulates metabolism and cardiovascular function

Answer 7

Parasympathetic nervous system (PSNS)

Question 8

Upregulated to help counteract elevated SNS activity

-more localized in its action than the SNS

Answer 8

PSNS

Question 9

The sympathetic chain is a series of ganglia located on either side of the vertebral column. What type of neurons are preganglionic SNS neurons?

Answer 9

Cholinergic fibers (i.e. ACh is their primary neurotransmitter)

Question 10

Dendrites and cell bodies of the post-ganglionic SNS fibers express ACh receptors, and these post-ganglionic cholinergic nreceptors can also bind

Answer 10

Nicotine

Question 11

Dendrites and Cell bodies of Post ganglionic SNS fibers have receptors that are thus identified as

Answer 11

Cholinergic-nicotinic (N2) receptors

Question 12

When choinergic-nicotinic receptors are bound to ACh or nicotine, they are activated and allow

Answer 12

Inward Na+ or Ca2+ current

Question 13

Branching of the axons of pre- and post-ganglionic fibers explains, in part, the diffuse action of the

Answer 13

SNS

Question 14

Post-ganglionic SNS fibers are considered to be

Answer 14

Noradrenergic (use norepinephrine as primary neurotransmitter)

Question 15

Cell plasma membranes of effector tissues that are innervated by the SNS fibers express

Answer 15

Adrenergic receptors

Question 16

Adrenergic receptors (adrenoceptors) are grossly classified as type α and β. These receptor families are subclassified as type

Answer 16

α1, α2, β1, β2, and β3

Question 17

The specific complement of receptor isoforms determines specificity of the response to

Answer 17

Adrenergic stimulation

Question 18

Adrenoreceptors belong to the family of

Answer 18

G-protein coupled receptors

Question 19

Can mobilize phospholipase C, and in turn ligand-gated Ca2+ channels can be activated

Answer 19

α1 adrenoreceptors

Question 20

Binding of adrenergics to α1 receptors in smooth muscle results in what 5 things?

Answer 20

1. ) activation of Gi proteins
2. ) Decrease in cGMP and cAMP production
3. ) Opening of membrane Ca2+ channels
4. ) Increase in sarcoplasmic [Ca2+]
5. ) Vasoconstriction

Question 21

Often associated with inhibitory effects on GI smooth
muscle contractility, inhibition of some glandular secretions, and inhibition of neurotransmitter
secretion

Answer 21

Activation of α2 adrenoreceptors

Question 22

Located on the prejunctional membrane of some post-ganglionic SNS fibers (e.g., cardiovascular)

Answer 22

α2 receptors

Question 23

When activated by adrenergics, these α2 receptors are involved in

Answer 23

Down regulating neurotransmitter release (negative feedback)

Question 24

Closely associated with stimulating Gs protein/cAMP signaling

Answer 24

β1 and β2 adrenoreceptors

Question 25

Predominant in the heart

Answer 25

β1 receptors

Question 26

Also expressed within the heart and couple to both stimulatory (Gs) and inhibitory (Gi) signaling motifs -also found in many smooth muscle beds

Answer 26

β2 receptors

Question 27

In the heart, the activation of β1 and β2 receptors results in increased

Answer 27

Heart rate (chronotropy) and cardiac contractility (inotropy)

Question 28

Also couple to Gi protein-mediated pathways which induce negative inotropy

Answer 28

Cardiac β2 receptors

Question 29

Associated with the relaxation of smooth muscle, hepatic glycogen metabolism, and glycogenolysis in skeletal muscle

Answer 29

β2 receptors

Question 30

In the kidney, activation of β1 receptors stimulates

Answer 30

Renin secretion from JG cells

Question 31

Synthesized in the axon termini of SNS post ganglionic neurons

Answer 31

Norepinephrine

Question 32

What are the steps of norepinephrine synthesis?

Answer 32

Tyrosine ---> L-dopa --->Dopamine ---> Norepinephrine

Question 33

Dopamine is converted to norepinephrine by

Answer 33

Dopamine β-hydroxylase

Question 34

Norepinephrine can be converted to epinephrine by

Answer 34

Phenolethaolamine N-methyltransferase

Question 35

A catcholamine that acts through two receptor isoforms

Answer 35

Dopamine

Question 36

Expressed within the vascular smooth muscle beds of the cerebral, renal, coronary and mesenteric circulations

Answer 36

Type 1 dopamine receptor (DA1)

Question 37

DA1 induces

Answer 37

Vasodilation

Question 38

Expressed within presynaptic SNS fibers and SNS ganglia

Answer 38

Type 2 dopamine receptor (DA2)

Question 39

Inhibits the secretion of norepinephrine as well as SNS ganglionic transmission

Answer 39

DA2

Question 40

After diffusing across the synapse, adrenergics bind to adrenoceptors on the

Answer 40

Post-synaptic membrane of the effector tissue

Question 41

Adrenergics can be degraded by

Answer 41

Catechol-O-methyl transferase (COMT) and/or monoamine oxidase (MAO)

Question 42

Secrets epinephrine and to a much lesser degree, norepinephrine

Answer 42

The adrenal medulla

Question 43

Preganglionic SNS fibers terminate within the adrenal medulla and synapse with modified post-ganglionic SNS neural cells called

Answer 43

Chromaffin cells

Question 44

Chromaffin cells synthesize

Answer 44

Epinephrine and norepinephrine

Question 45

Chromaffin cells are stimulated by

Answer 45

ACh

Question 46

Adrenal-derived epi supports the action of the norepi that is locally secreted from

Answer 46

Post-ganglionic SNS fibers

Question 47

Has a high binding affinity for both α and β adrenoreceptors -dose-dependent

Answer 47

Epinephrine

Question 48

At all doses, Epinephrine is a potent

Answer 48

β1 agonist

Question 49

At a low dose, epinephrine tends to bind B2 receptors and induce

Answer 49

Vasodilation

Question 50

At a high dose, epinephrine binds α1 adrenoreceptors and thus induces

Answer 50

Vasoconstriction

Question 51

A potent α1 and β1 agonist and thus augments both systolic (β1) and diastolic (α1) blood pressure

Answer 51

Norepinephrine

Question 52

At lower doses, norepinephrine does not have as much of an effect on cardiac function, but instead exerts more of a

Answer 52

Presser effect (α1 mediated vasoconstriction)

Question 53

Norepinephrine has a lower affinity for

Answer 53

β2 adrenoreceptors

Question 54

So called beta blockers (e.g., atenolol and metoprolol) are type β1 adrenoceptor antagonists; these agents are used to

Answer 54

Lower heart rate and contractility

Question 55

Commonly used beta blockers with a high degree of specificity against β1 adrenoceptors

Answer 55

Atenolol and metoprolol

Question 56

The SNS stimulates increased arterial BP through

Answer 56

Increased cardiac output (B1) and vasoconstriction (a1)

Question 57

What is responsible for the increased blood flow to contracting skeletal muscle seen in SNS response?

Answer 57

B2

Question 58

What is responsible for the concurrent decreased blood flow to non-contracting skeletal muscle and the GI tract?

Answer 58

a1

Question 59

SNS response of increased glycolysis in the liver and skeltal muscle is due to

Answer 59

B2 activation

Question 60

What mediates the following SNS responses? 1. ) Decreased insulin secretion 2. ) Upregulated glycogenolysis resulting in increased plasma glucose level

Answer 60

1. ) a2 and pancreatic B cells | 2. ) B2 activation, hepatocytes, and skeletal muscle

Question 61

What mediates the following SNS responses? 1. ) Bronchial smooth muscle relaxation 2. ) Increased platelet aggregation

Answer 61

1. ) B2 ativation | 2. ) a2 activation

Question 62

Compounds which stimulate adrenoceptor activity (adrenoceptor agonists)

Answer 62

Sympathomimetics

Question 63

Endogenous as well as pharmacologic adrenoreceptor agonists

Answer 63

Epinephrine and norepinephrine

Question 64

Low concentrations of epinephrine stimulates both B1 and B2 activity whereas high concentrations function as more of an

Answer 64

a1 agonist

Question 65

A very effective a1 and B1 agonist but has little B2 effect

Answer 65

Norepinephrine

Question 66

Impair SNS activity by blocking adrenoceptor activity

Answer 66

Adrenoreceptor antagonists

Question 67

Suppress vascular smooth muscle tone and thus are useful for reducing hypertension

Answer 67

Alpha blockers

Question 68

Non-specific alpha blockers have a suppressive effect on presynaptic a2 receptors and will cause

Answer 68

Reflex tachycardia

Question 69

Widely used to control angina and hypertension

Answer 69

Beta blockers

Question 70

Beta agonists are indicated to control

Answer 70

Asthma

Question 71

Beta blockers with a relatively high specificity for the B1 adrenoreceptor

Answer 71

Atenolol and Metoprolol

Question 72

An example of a non-specific beta blocker is

Answer 72

Propranolol

Question 73

Cell bodies of the preganglionic PSNS neurons originate within the

Answer 73

Brainstem and sacral region of the spinal cord

Question 74

Myelinated axons emerging from the brainstem are distributerd within which 4 nerves?

Answer 74

Cranial Nerves 1. ) III (oculomotor) 2. ) VII (facial) 3. ) IX (glossopharyngeal) 4. ) X (vagus)

Question 75

Approximately 75% of the axons of preganglionic PSNS fibers are in the

Answer 75

Vagus nerve

Question 76

Myelinated axons of the sacral PSNS neurons are distributed with

Answer 76

Pelvic nerves

Question 77

These fibers are choinergic and terminate in ganglia that are seated very near to the effector tissues

Answer 77

Preganglionic PSNS neurons

Question 78

Like postganglionic SNS fibers, post-ganglionic PSNS fibers have

Answer 78

Cholinergic-nicotinic receptors (and are unmyelinated)

Question 79

All pre-ganglionic ANS neurons are

Answer 79

Cholinergic

Question 80

Dendrites and cell bodies of all post-ganglionic ANS neurons express

Answer 80

Cholinergic nicotinic receptors

Question 81

Cholinergic nicotinic receptors are functionally classified as

Answer 81

Ligand-coupled (or ligand-activated) Na+ channels

Question 82

Effectors that respond to PSNS activity posses which type of receptors? -G-protein coupled receptors

Answer 82

Cholinergic-muscarinic (CM) receptors

Question 83

ACh is synthesized in the PSNS nerve termini via the reaction between

Answer 83

Acetyl-CoA and choline

Question 84

ACh synthesis is fairly exclusive to

Answer 84

Pre-ganglionic ANS fibers and Post-ganglionic PSNS fibers

Question 85

Can synthesize ACh, but rely upon extracellular choline as the substrate for ACh production

Answer 85

α motor neurons

Question 86

Binds to cholinergic receptors (either muscarinic or nicotinic) on the post-synaptic membrane

Answer 86

ACh

Question 87

Upon binding, ACh is rapidly degrade by

Answer 87

ACh esterase (cholinesterase)

Question 88

A hydrolytic product of cholinesterase activity, can be re-uptaken by the presynaptic terminus and recycled for the re-synthesis of ACh

Answer 88

Choline

Question 89

Compounds that can activate PSNS activity

Answer 89

Chiolinomimetics

Question 90

Compounds which can impair PSNS activity

Answer 90

Muscarine antagonists

Question 91

Muscarine antagonists will block the effects of (post-ganglionic) muscarine, and thus have a wide variety of uses. A common example is

Answer 91

Atropine

Question 92

Uses include: 1. ) Anesthesia: block vagal activity to reduce salivary and bronchial secretions and alleviate the inhibition of heart rate 2. ) Pupil dilation 3. ) Prevention of motion sickness 4. ) Reduction in intestinal spasm

Answer 92

Muscarine antagonists such as atropine