36 Questions
What is the typical structure of the autonomic nervous system?
Two-neuron structure
Where is the cell body of the preganglionic neuron located in the sympathetic nervous system?
Thoracic and lumbar spinal cord
What is the neurotransmitter released by sympathetic neurons?
Norepinephrine
What is the neurotransmitter released by cholinergic neurons?
Acetylcholine
Where are the preganglionic neurons of the parasympathetic nervous system located?
Brainstem and sacral spinal cord
Which part of the spinal cord has the most spinal nerves?
Thoracic
What is the primary mechanism by which beta-adrenergic blocking agents reduce cardiac output?
Block cardiac beta-1 receptors leading to lower HR and lower CO
Which of the following is a 2nd generation beta blocker?
Metoprolol
What is the effect of beta-adrenergic blocking agents on the SA node and ectopic pacemakers?
Decrease in automaticity
Which of the following is a clinical use of beta-adrenergic blocking agents?
Treatment of migraine
What is the effect of beta-adrenergic blocking agents on the refractory period of the AV node?
Increase in refractory period
What is the mechanism by which beta-adrenergic blocking agents reduce renin secretion?
Block renal beta-1 receptors
Which of the following beta blockers is a hybrid, having both alpha and beta blocking properties?
Labetalol
Which receptor subtype is responsible for the vasoconstriction effect of norepinephrine?
Alpha 1
What is the primary mechanism of action of indirect-acting adrenergic agonists?
Inhibiting the reuptake of norepinephrine
What is the effect of dopamine on the renal vascular bed?
Vasodilation
What is the primary use of fenoldopam?
Rapid vasodilation for severe hypertension in hospitalized patients
What is the mechanisms of action of guanethidine?
Depleting norepinephrine from nerve endings
Which of the following is a mixed alpha and beta receptor agonist?
Epinephrine
What is the primary therapeutic use of dobutamine?
Treatment of congestive heart failure
What is the effect of alpha 2 receptors on dilator muscle?
Relaxation
Where is endogenous epinephrine produced?
Medulla of the adrenal gland
What is the effect of epinephrine on uveal scleral outflow?
Increase
What is the use of 1% epinephrine in the treatment of POAG?
Hypotensive effect
What is the diagnosis where epinephrine is used?
Horner's syndrome
What is the side effect of epinephrine in aphakic patients?
Maculopathy
What is the characteristic of phenylephrine?
Alpha 1 agonist
What is the duration of action of 2.5% and 10% phenylephrine?
45-60 minutes
What is the primary mode of action of Brimonidine tartrate in reducing intraocular pressure?
Decreases aqueous humor production
What is the main advantage of Betaxolol over other beta blockers in glaucoma treatment?
It is a beta-1 selective blocker
What is the primary action of Dapiprazole on the eye?
It reversibly blocks alpha 1 receptors on the dilator muscle
Why is Cocaine not commonly used in ophthalmic practice?
It is not commercially available in ophthalmic solution
What is the primary mechanism of action of Aproclonidine in reducing intraocular pressure?
It decreases aqueous humor production
What is the primary indication for Combigan?
Treatment of glaucoma
What is the main side effect of Lumify that is unique to this medication?
Blanching
Why is Carteolol considered a safer option for some patients?
It increases the ratio of high density lipids to total cholesterol
Study Notes
Regulation of Biological Process
- Hormones: regulate various physiological processes
- Neurotransmitters: transmit signals between neurons
- Histamine: involved in allergic responses
- Prostaglandins: involved in inflammation and smooth muscle contraction
Organization of the Nervous System
- Afferent (sensory) neurons -> PNS -> Efferent (motor) neurons -> Autonomic Nervous System (ANS) or Somatic Nervous System
- Thoracic region has the most spinal nerves
- ANS: regulates involuntary actions (e.g., heart rate, digestion)
- Subdivisions: Sympathetic, Parasympathetic, and Enteric systems
Autonomic Nervous System (ANS)
- Sympathetic system:
- Preganglionic neuron in thoracic and lumbar spinal cord
- Produces widespread physiological activity
- Uses norepinephrine as neurotransmitter
- Parasympathetic system:
- Preganglionic neuron in brainstem and sacral spinal cord
- Produces response on an organ basis
- Uses acetylcholine as neurotransmitter
Neurotransmission
- 3 stages: Preganglionic synapse, Postganglionic synapse, Metabolites excreted in urine
Classification of Beta-Adrenergic Blocking Agents
- Non-selective (1st gen)
- Cardioselective (beta-1 selective, 2nd gen)
- Hybrid antihypertensive drugs (3rd gen)
Clinical Uses of Beta-Blockers
- Hypertension
- Angina pectoris
- Glaucoma
- Migraine
- Thyrotoxicosis
- Arrhythmia prophylaxis
Adrenergic Agonists
- Direct action: drug directly activates receptor
- Indirect action: drug enhances release of norepinephrine
- Mixed action: drug acts both directly and indirectly
- Examples:
- Tyramine (indirect action)
- Cocaine (indirect action)
- Amphetamines (indirect action)
- Pseudoephedrine (direct action)
- Ephedrine (direct action)
Adrenergic Antagonists
- Decrease sympathetic tone of blood vessels
- Results in decrease in total peripheral resistance (TPR)
- Examples:
- Phenoxybenzamine (non-competitive antagonist)
- Phentolamine (competitive reversible antagonist)
Alpha Adrenergic Receptors
- Alpha 1:
- Works through phospholipase C pathway
- Increases intracellular Ca++ in smooth muscle cells
- Contraction of smooth muscle
- Alpha 2:
- Works through adenylate cyclase pathway
- Decreases release of neurotransmitters and hormones
Beta Adrenergic Receptors
- Beta 1:
- Works through stimulation of adenylate cyclase pathway
- Increases cardiac muscle contraction
- Beta 2:
- Works through stimulation of adenylate cyclase pathway
- Relaxation of smooth muscle
- Beta 3:
- Works through stimulation of adenylate cyclase pathway
- Lipolysis in adipose tissue
Test your knowledge of the autonomic nervous system, including its structure and function, as well as the role of hormones and neurotransmitters like histamine and prostaglandins. Learn about the organization of the nervous system and the different types of neurons involved.
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