Chapter 9 Sympathetic Nervous System

Question 1

Synthesis of catecholamines

Answer 1

Tyr> Dopa> Dopamine> Epinephrine> NE

Degradation by MAO in synapse and by COMT in end organ

Question 2

Receptor types

Answer 2

Alpha-1 & 2

Beta 1,2,3

Question 3

Sympathetic system

Answer 3

“PUMP IT UP”

responsible for directing the body’s rapid involuntary response to dangerous or stressful situations

Question 4

Alpha Adrenoceptors

Answer 4

1. Alpha-1
   arterioles, iris radial muscle, nasal mucosa
   (leads to constriction/vasoconstriction {pupil dilation})
   - coupled to PLC»IP3»Ca2+ release
2. Alpha-2
   Sympathetic nerves, vascular smooth muscle, pancreas
   (Leads to presynaptic inhibition of NE, direct constriction, and inhibition of insulin release and lipolysis)
   - inhibits AC (less cAMP)

Question 5

Beta Adrenoceptors

Answer 5

1. Beta-1
   increase myocardial constriction/heart rate
   increase renin release
2. Beta-2
   vasodilation and bronchodilator
   increase liver glycogenolysis
3. Beta-3
   increase fat breakdown (lipolysis)

Question 6

Metabolic effects of Catecholes

Answer 6

1. stimulate liver to release glucose
   - both glycogenolysis and gluconeogenesis
2. reduce pancreatic secretion of insulin
   - overall EPI inhibits insulin release
3. increase lipolysis and breakdown of triglycerides to Free Fatty Acids

Question 7

Uses of Catecholes

Answer 7

1. Epinephrine
   - in bronchospasm & anaphylaxis
   - cardiac arrest
   - superficial hemorrhage
   - with local anesthetics to reduce drug level
2. Norepinephrine
   - for hypotensive shock

Question 8

Sympathomimetics

Answer 8

1. Indirect acting
   - Tyramine: taken up; causes NE release/ deplete
2. Mixed action; deplete & act as receptors
   - Amphetamine & Ephedrine: for ADD, appetite suppression, and nasal decongestion
   - ——> Cause nervousness & anxiety
   - Phenylopropanolamine: for appetite suppression
3. Direct acting

Question 9

Direct Acting Sympathomimetics

1. Alpha-1 agonists

Answer 9

• For hypotensive shock, hemorrhage, nasal decongestion, mydriasis

side effects: raise BP, headache, bradycardia

Agents: Midodrine, phenylephrine, pseudoephedrine

Question 10

Direct Acting Sympathomimetics

2. Alpha-2 agonists

Answer 10

• For hypertension, ADD/ADHD, or reduce intraoccqular pressure
• Decrease sympathetic outflow centrally
  Agents: clonidine, guanabenz, guanfacine

side effects: dizziness, drowsiness, dry mouth

Question 11

Direct Acting Sympathomimetics

3. Beta-1 agonists (Agent: Dobutamine)

Answer 11

• To increase cardiac output after surgery

Side effects: chest pain, arrhythmia

Question 12

Direct Acting Sympathomimetics

4. Beta-2 agonists

Answer 12

• For anaphylaxis, bronchial asthma, emphysema, reduce premature labor

Agents: Metaproterenol, albuterol

side effects: nervousness, can increase maternal heart rate & B.P. ; can make airways hypersensitive

Question 13

Direct Acting Sympathomimetics

5. B-3 agonists

Answer 13

Mirabegron: for reduction in bladder tone during bladder urgency

Question 14

Dopamine agents

Answer 14

D-1: Fenoldopam
- Used to reduce BP due to vasodilatory effect (hypersensitive emergency)

D-2: Bromocriptine
- Used for CNS effects (EX: PARKINSON’S)