Sympathetic Nervous System Flashcards
What compounds can mimick sympathetic effects?
- Andregenic Receptor Agonists (Direct Acting)
- Norephinephrine Uptake Blockers (indirect Acting)
- Monoamine Oxidase and COMT inhibitors (Indirect)
- NE releasing agents (indirect)
MO and COMT inhibitors delay breakdown of NE, E, Dopamine
What compounds can block sympathetic effects?
Andregenic Receptor Antagonists
Explain NE termination at the synapse.
What type of receptors can Epinephrine Activate?
Equal Activation at all subtypes - Alpha and Beta.
What type of receptors can NE activate?
Can activate Alpha and Beta 1 receptors. Little effect on B2. NE not a good bronchodilater.
What receptors can Dopamine Activate?
Activates Cardiac B1 receptors.
Can activate kidney dopamine receptors causing increase in blood flow
What are the main sympathetic receptors in the heart and what are the effects produces from stimulation and blocking of these receptors?
B1 - 80 Percent
B2 - 20 Percent
Stimulation of both produce same effects
What is a therapeutic use of Beta and Selective Beta 1 Agonists on the heart?
- To treat cardiogenic shock and stimulate contractility.
- Used for Allergic Reactions: Epiephrine (Increase contracility, constricts and dilates vessels to maintain BP, bronchodilation, removal of mediators from mast cells.
- To treat Resistant Heart Failure - B1 Agonist (Not first choice)
Adverse Effect: Arrythmias (Overstimulation)
Should Not Use: Patients with cardiac conditions.
What is the therapeutic use of Beta and Beta 1 blockers on the heart?
Most Widely used drugs for cardiovascular conditons.
Used to treat hypertension, cardiac arrythmias, congestive heart failure etc.** Decrease Atrioventricular Conduction, Decrease Contractility. **
Adverse Effects: Can Cause Bradycardia or Heart Block
Should Not Use: Patients who have Conduction Defects involving the AV Node
What are the sympathetic receptors for Blood vessels and what is the effect of the stimulation and blocking of these receptors?
A1 however some vessels(skeletal muscle vessels) have beta 2 receptors which produce vasodilation.
What are the therapeutic uses for alpha 1 agonists for blood vessels?
Used to treat hypotension. Produce local vaoconstriction. Treat Nasal Decongestion (Constricts Mucosal Vessels)
Adverse Effects: Reflex Bradycardia (triggers baro-reflex)
Should Not Use: With Patients with Arrythmias of Vascular Conditions.
What are the therapeutic uses of Alpha 1 blockers for blood vessels?
**Used to treat hypertension. **
Adverse Effect: Reflex Tachycardia (increased blood pressure triggers the Baro - reflex) - Due to Vasodilation of B2 vessels.
Remember: Skeletal muscle, pulmonary, abdominal viscera, renal and coronary vessels have β2
receptors which cause VASODILATION and decrease vessel resistance. E.g. epinephrine will
dilate these vessels, NE will not (little B2 activity)
What is the therapeutic use of Alpha 2 agonist in blood vessels?
Alpha 2 is presynaptic - prevents release of NE from nerve terminal through negative feeback inhibition.
**Used to treat hypertension **- A2 agonist has anti sympathetic effect.
What is the therapeutic use of Beta blockers in blood vessels?
**Prevents vasodilation of blood vessels where these receptors are present.
***
Non selective beta blockers used for glaucoma because they reduce secretion of ciliary body.
No such thing as selective Beta 2 blocker yet
What is the dominant tone of the kidney?
Sympathetic
What is the sympathetic receptors in the kdiney and what are the effects from stimulation and blocking of these receptors.
B1
What are the therapeutic uses of Beta blockers and B1 blockers on the Kidney?
Decrease renin-angiotensin aldosterone activity redcuing blood pressure.
What are the sympathetic receptors in the Urinary Bladder and what are the effects from the stimulation and blocking of these receptors?
B3 (Not significant), A1 (Internal Sphincter)
What are the therapeutic uses of Alpha 1 blockers for the Urinary bladder?
To treat difficulty emptying the bladder of benign prostatic hyperplasia.
Almost always treatment of first choice
What are the sympathetic receptors of the GI Tract and what is the effect of stimulation and blocking of these receptors?
A1, A2, B1, B2
What are the sympathetic receptors of salivary glands and what are the effects from stimulation and blocking of these receptors?
A1
What is the dominant tone of the Liver?
Sympathetic
What are the sympathetic receptors in the liver and what effect to they have from the stimulation and blocking of these receptors.
B2
**Stimulation of B2 by epinephrine causes Glycogenolysis and gluconeogenesis. **
What is the clinical relevance of Non selective B blockers in the liver?
Type 1 diabetic patients on insulin ar eprone to develop hypoglycemia and coma as a serious side effect of insulin. Sympathetic system is activated during hypoglycemia and helps release glucose to correct the coma.
Non Selective Beta Blockers block this.
Should not give non selective B blockers to Type 1 Diabetics.
