Week 3: Autonomic Nervous System Flashcards
What are the sympathetic and parasympathetic effects of stimulation on pupils?
Sympathetic: dilate
Parasympathetic: constrict
What are the sympathetic and parasympathetic effects of stimulation on salivation?
Sympathetic: decreases saliva production
Parasympathetic: increases saliva production
What are the sympathetic and parasympathetic effects of simulation on heart rate?
Sympathetic: increase
Parasympathetic: decrease
What are the sympathetic and parasympathetic effects of simulation on contractility (strength of heart contraction)?
Sympathetic: increase
Parasympathetic: decrease
What are the sympathetic and parasympathetic effects of simulation on the bronchi?
Sympathetic: bronchiole dilation
Parasympathetic: bronchiole constriction
What are the sympathetic and parasympathetic effects of simulation on the GI tract?
Sympathetic: decreases activity
Parasympathetic: increases activity
What are the sympathetic and parasympathetic effects of simulation on the adrenal medulla?
Sympathetic: increases epinephrine (and some norepinephrine) release
Parasympathetic: N/A
What are the sympathetic and parasympathetic effects of simulation on urination?
Sympathetic: decreases urination (relaxes urinary bladder, constricts sphincter)
Parasympathetic: increases urination (constricts urinary bladder, relaxes sphincter)
What are the sympathetic and parasympathetic effects of simulation on vasculature?
Sympathetic: general vascular tone. Increased sympathetic response leads to vasoconstriction.
Parasympathetic: N/A
Which branch of the ANS innervates sweat glands?
SNS
Which branch of ANS innervates blood vessels?
SNS
What is the somatic nervous system?
Nerve impulses that are under voluntary control as well as reflexes
4 main neurotransmitters of the ANS
- Epinephrine
- Norepinephrine
- Acetylcholine
- Dopamine
What is a synapse?
The endpoint of a nerve where it releases its neurotransmitter for cell to cell communication.
The recipient cell can be another nerve cell or of the target organ.
What neurotransmitter is released by the somatic nervous system?
What receptor binds this neurotransmitter here?
Acetylcholine
Nicotinic (type 1) receptor
What neurotransmitter is released into the synapse at all autonomic ganglion?
What receptor binds this neurotransmitter here?
Acetylcholine
Nicotinic (type 2) Receptor (Or Nn receptor)
What neurotransmitter is released onto target organs from the parasympathetic nervous system?
What receptor binds this neurotransmitter here?
Acetylcholine
Muscarinic (M) Receptor
What neurotransmitter is released onto target organs from the sympathetic nervous system?
What receptors bind this neurotransmitter here?
Norepinephrine
Adrenergic Receptors (alpha1, alpha 2, Beta 1, Beta 2)
What neurotransmitter is released by the adrenal medulla?
Where does this neurotransmitter go?
Primarily epinephrine (some norepinephrine)
It goes into the vascular circulation
How and where is acetylcholine metabolized?
Acetylcholinesterase (AChE) in synaptic cleft
How and where is epinephrine metabolized?
Primarily COMT, sometimes MAO in presynaptic terminal
If in systemic circulation, metabolized by liver
How and where is norepinephrine metabolized?
Primarily MAO, sometimes COMT in presynaptic terminal
Autonomic tone
Steady balance of SNS and PNS innervation
How does the baroreceptor reflex respond to low blood pressure?
Vasoconstriction and Inc. CO
How does the baroreceptor reflex respond to high blood pressure?
Vasodilation and Dec. CO
What are the 2 main effects of alpha-1 stimulation and where can you find the receptor?
Postsynaptic
1. Vasoconstriction
2. Prostate contraction
List all the effects of alpha-1 stimulation and where you can find the receptor (7)
All postsynaptic
1. Vasoconstriction
2. Prostate contraction
3. Pupil dilation
4. Bladder sphincter contraction
5. Uterine contraction
6. Hair erection
7. Ejaculation
What is the main effect of alpha-2 stimulation and where can you find the receptor?
Presynaptic
Dec. SNS outflow -> sedation
List all the effects of alpha-2 stimulation and where you can find the receptor (6)
Postsynaptic
1. Platelet aggregation
2. Vasoconstriction
Presynaptic
3. Inhibition of NT release
4. Vasodilation
5. GI relaxation
6. Dec. SNS outflow -> sedation
What is the main effect of beta-1 stimulation and where can the receptor be found?
Postsynaptic
Think heart: Inc. contractility, Inc. HR, Inc. AV node conduction velocity
List all the effects of beta-1 stimulation and where you can find the receptor (2)
All postsynaptic
1. Heart: Inc. contractility, Inc. HR, Inc. AV node conduction velocity
2. Renin release from kidneys
What are the main effects of beta-2 stimulation and where you can find the receptor (6)
All postsynaptic
1. Bronchodilation
2. Uterine relaxation
3. Vasodilation in skeletal muscle, heart, and lungs
4. Dec. GI/GU motility
5. Inc. K+ uptake -> tremor
6. Glycogenolysis
List the main effects of dopamine-1 stimulation and where you can find the receptor
Postsynaptic
Vasodilation of coronaries and renal vasculature
Agonist
Stimulates the receptor to do what it normally does
Antagonist
Blocks the normal activated receptor activity
Affinity
Strength of drug binding to the receptor
What is a catecholamine?
NT of SNS
Characteristics of catecholamines
Can’t be given PO
Can’t cross BBB
Short half-life bc metabolized by MAO and COMT
Characteristics of non-catecholamines
Can be given PO
Can cross BBB
Longer half-life bc not metabolized by COMT, only slowly metabolized by MAO
Possible complications of MAO inhibitor
Hypertension and tachycardia
Norepinephrine: Class and receptor selectivity
Adrenergic agonist
a1, a2, B1
Ephedrine: Class and receptor selectivity
Indirect agonist
a1, a2, B1
Phenylephrine: Class and receptor selectivity
A1 agonist
a1>a2
Clonidine: Class and receptor selectivity
A2 agonist
a2>a1
Dexmedetomidine: Class and receptor selectivity
A2 agonist
a2>a1
Dobutamine: Class and receptor selectivity
B1 agonist
B1>B2
Isoproterenol: Class and receptor selectivity
B1/B2 agonist
B1 and B2
Terbutaline: Class and receptor selectivity
B2 agonist
B2>B1
Albuterol: Class and receptor selectivity
B2 agonist
B2>B1
List the two synthetic catecholamines
Dobutamine and isoproterenol
Dopamine: Class and receptor selectivity
Adrenergic agonist
D1 = D2 > B1 > A1
Epinephrine: Class and receptor selectivity
Adrenergic agonist
a1, a2, B1, B2
Epinephrine: Indications + contraindications
Indications:
- Bronchoconstriction due to asthma
- Acute allergic reaction
- Cardiac arrest
- Dec. myocardial contractility
Contraindications:
- Tachydysrhythmia
Epinephrine: What’s unique?
Adrenergic agonist prototype, rapid onset, short duration unless used via IV
Norepinephrine: Indications + contraindications
Indications:
- Acute hypotension
- Any need for extreme vasoconstriction
Contraindications:
- Risk for metabolic acidosis
- Risk for tissue necrosis if extravasation
Norepinephrine: What’s unique?
- Vasoconstriction is unopposed
- No glycogenolysis or hyperglycemia
Dopamine: Indications + contraindications
Indications:
- Renal dose: Hemodynamic imbalances for renal, splanchnic, and cerebral blood flow
- Low dose: Want to inc. CO without inc. HR
- High dose: Need for general vasoconstriction
Contraindications:
- Higher dose = less specificity
Ephedrine: Indications + contraindications
Indications:
- Bradycardia
- Hypotension
Contraindications:
- HTN
- Can cause hypertensive crisis
Ephedrine: What’s unique?
Indirect agonist: Blocks uptake of NE, prolonging NE in synapse
Phenylephrine: Indications + contraindications
Indications:
- Hypotension
- Nasal congestion
Contraindications:
- HTN
Phenylephrine: What’s unique?
Vasoconstriction with no HR or contractility agonism
Clonidine: Indications + contraindications
Indications:
- Hypertension
- Need for sedation
Contraindication:
- Hypotension
Clonidine: What’s unique?
More routes of administration routes available
Dexmedetomidine: Indications + contraindications
Same as clonidine
Isoproterenol: Indications
Indications:
- Heart block
Isoproterenol: What’s unique?
“Chemical pacemaker” (inc. HR, contractility, and bronchodilation)
Dobutamine: Indications
Indications:
- Chronic heart failure
Dobutamine: What’s unique?
Inc. contractility without inc. HR or BP substantially (by dilating coronary arteries)
Albuterol: Indications + contraindications
Indications:
- Asthma-induced bronchospasm
Contradictions:
- Hypokalemia
- Hyperglycemia in diabetics
Albuterol: What’s unique?
Largely asthma use
Terbutaline: Indications + contraindications
Indications:
- General respiratory distress that causes bronchoconstricton
- Premature labor
Contradictions:
- Hypokalemia
- Hyperglycemia in diabetics
Terbutaline: What’s unique?
Use for bronchodilation AND premature labor
Phentolamine: Class and receptor selectivity
A antagonist
A1 = A2
Phenoxybenzamine: Class and receptor selectivity
A antagonist
A1 = A2
Prazosin: Class and receptor selectivity
A1 antagonist
A1»_space; A2
Metoprolol, Atenolol, Esmolol: Class and receptor selectivity
B1 antagonist
B1»_space; B2
Propranolol: Class and receptor selectivity
B antagonist
B1 = B2
Labetalol, Carvedilol: Class and receptor selectivity
B antagonist + A at high doses
B1 = B2 > A1 > A2
Phentolamine: Indications and contraindications
Indications:
- HTN
- Pheochromocytoma
- Local infiltration post-extravasation
Contraindications/AE:
- Orthostatic hypotension
- Reflex tachycardia
- Nasal conjestion
- Inhibition of ejaculation
Phenoxybenzamine: Indications and contraindications
Indications:
- Pheochromocytoma management until surgery
Contraindications/AE:
- Orthostatic hypotension
- Reflex tachycardia
- Nasal congestion
- Inhibition of ejaculation
Prazosin: Indications and contraindications
Indications:
- HTN
- Benign prostatic hyperplasia (BPH)
Contraindications/AE:
- Orthostatic hypotension
- Reflex tachycardia
- Nasal congestion
- Inhibition of ejaculation
Metoprolol, Atenolol, Esmolol: Indications and contraindications
Indications:
- HTN
- Angina
- Post-MI / pre-op at risk for MI
- Tachyarrhythmias
- Excessive SNS activity
Contraindications/AE:
- AV heart block
- Cardiac failure
- Restrictive airway disease
- Uncontrolled diabetes
- Hypovolemia
Propranolol: Indications and contraindications
Indications:
- HTN
- Angina
- Essential tremor
- Post-MI / pre-op at risk for MI
- Tachyarrhythmias
- Excessive SNS activity
Contraindications/AE:
- AV heart block
- Cardiac failure
- Restrictive airway disease
- Uncontrolled diabetes
- Hypovolemia
Labetalol, Carvedilol: Indications and contraindications
Indications:
- HTN
- Angina
- Post-MI / pre-op at risk for MI
- Tachyarrhythmias
- Excessive SNS activity
Contraindications/AE:
- AV heart block
- Cardiac failure
- Restrictive airway disease
- Uncontrolled diabetes
- Hypovolemia
- Orthostatic hypotension
- Bronchospasm
- CHF
- Bradycardia
Phentolamine: What’s unique?
Shorter acting than phenoxybenzamine
Phenoxybenzamine: What’s unique?
Uses covalent binding, thus, very long-acting. Long-term use inc. risk for cancer
Atenolol: What’s unique?
Most selective B blocker, very useful in those with coronary artery disease
Nn/N1 receptor: Locations
All ANS ganglia
Adrenal medulla
Nn/N1 receptor: Actions
ANS ganglia -> Agonizes post-ganglion nerves
Adrenal medulla -> Release Epi/NE
M1 receptor: Location
Blood vessels (no nerve synapse)
M1 receptor: Action
Vasodilation
M2 receptor: Location
Heart
M2 receptor: Action
Dec. HR
M3 receptor: Locations (5)
Eye
Lung
Bladder
Sweat glands
Sex organs
M3 receptor: Actions (5)
Eye: Miosis, ciliary musc. contraction (near vision)
Lung: Bronchoconstriction, inc. secretions
Bladder: Facilitates urination
Sweat glands: Sweating
Sex organs: Erection
M1-5 receptor: Location
CNS
M1-5 receptor: Action
Memory
Atropine: Class and BBB status
Anticholinergic (Cholinergic antagonist)
Can cross BBB
Scopolamine: Class and BBB status
Anticholinergic (Cholinergic antagonist)
Can cross BBB
Glycopyrrolate: Class and BBB status
Anticholinergic (Cholinergic antagonist)
Can’t cross BBB
Ipratopium: Class and BBB status
Anticholinergic (Cholinergic antagonist)
Can cross BBB
Atropine: Indications and contraindications
Indications:
- Bradycardia
- Excess salivary/respiratory secretions
- Cycloplegia for eye exams and surgery
- Excessive GI motility
- Bronchoconstriction caused by asthma
Contraindications:
- Glaucoma
- Dry mouth
- Blurry vision
- Tachycardia
- Constipation
Scopolamine: Indications and contraindications
Indications:
- Use for sedation
- Mydriasis
- Sea sickness
Contraindications/AE:
- Glaucoma
- Dry mouth
- Blurry vision
- Tachycardia
- Constipation
Glycopyrrolate: Indications and contraindications
Indications:
- Excess salivary and respiratory secretions
- Reversal of muscarinic effects of cholinergic agents
Contraindications/AE:
- Glaucoma
- Dry mouth
- Blurry vision
- Tachycardia
- Constipation
Ipratropium: Indications and contraindications
Indications:
- Bronchoconstriction from asthma or COPD
Contraindications/AE:
- Glaucoma
- Dry mouth
- Blurry vision
- Tachycardia
- Constipation
Describe the actions of cholinergic antagonists
- Antagonizes ACh at all muscarinic receptors
- Doesn’t cause vasoconstriction, just blocks vasodilation
- Reverses effects of cholinergic agonists
Blocks PSNS response, mimics SNS response
Bethanechol: Class
Muscarinic agonist
Bethanechol: Indications and contraindications
Indications:
- Dec. GI/GU motility, especially post-op, post-partum, neurogenic bladder
Contraindications/AE:
- Bowel/bladder obstruction
- Heart block
- Hypotension and bradycardia
- Asthma
- Inc. secretions
- Sweating
- Bronchoconstriction
- Miosis
Describe the actions of AChE inhibitors
- Binds to AChE making it unfunctional
- Leads to more ACh to interact with receptors -> inc. response
Indirectly inc. PSNS response
Neostigmine: Class
AChE inhibitor
Pyridostigmine: Class
AChE inhibitor
Neostigmine: Indications and contraindications
Indications:
- Myasthenia gravis
- Neuromuscular block (NMB)
- Slow GI/GU motility
Contraindications/AE:
- Unstable/severe cardiac disease
- Uncontrolled epilepsy
- Active peptic ulcer disease
- GI/GU obstruction
- Bradycardia
Pyridostigmine: Indications and contraindications
Indications:
- Glaucoma
- Myasthenia gravis
- Neuromuscular block (NMB)
Contraindications/AE:
- Unstable/severe cardiac disease
- Uncontrolled epilepsy
- Active peptic ulcer disease
- GI/GU obstruction
- Bradycardia
Neostigmine: What’s unique?
Can be used to improve GI/GU motility
Pyridostigmine: What’s unique?
Can be used for glaucoma
Cholinergic crisis: Cause, presentation, and treatment
Cause: AChE inhibitors or muscarinic agonists
Presentation: Extreme muscle weakness, salivation, cramps
Treatment: Atropine, supportive care for respiratory failure
Myasthenic crisis: Cause, presentation, and treatment
Cause: Myasthenia gravis
Presentation: Extreme muscle weakness
Treatment: AChE inhibitor, supportive care for respiratory failure
How can you tell if a patient is experiencing a myasthenic crisis or a cholinergic crisis?
- Take patient history for indications of autoimmune disorders
- Give patient a short-acting AChE inhibitor and monitor CLOSELY. If patient gets worse, they are experiencing a cholinergic crisis
Succinylcholine: Class
Depolarizing NMB
Nm agonist
Describe the actions of Nm agonists
- Agonizes Nm at neuromuscular junction -> continuous Nm activation
- Muscle contracts and then relaxes but cannot receive another action potential
Succinylcholine: Indications and contraindications
Indications:
- Any need for complete paralysis
Contraindications/AE:
- No sedation or analgesia
- Hyperkalemia
- Muscle pain
Rocuronium: Class
Nondepolarizing NMB
Nm antagonist
Describe the actions of Nm antagonists
- Binds to Nm to prevent ACh from binding
- Muscle cannot depolarize, no muscle contraction
Succinylcholine: What’s unique?
Short duration, broken down by pseudocholinesterase
Rocuronium: Indications and contraindications
Indications:
- Any need for complete paralysis
Contraindications/AE:
- No sedation or analgesia
Rocuronium: What’s unique?
- Good for patients with end-stage renal disease (since no hyperkalemia)
- Straight to flaccid paralysis
