Adrenergic Agonists and Adrenergic Blockers

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Alpha 1

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Increases the force of contraction, vascoconstriction increases BP, mydriasis (dilation of pupils) occurs, decreases secretions in the salivary glands and increases urinary bladder relaxation and urinary sphincter control.
When alpha1 receptors in vascular tissues of muscles are stimulated the arterioles and venules constrict which increases peripheral resistance and blood return to the heart. Ciruclation is improved and BP increases. If it is too much stimulation, the blood flow is decreased to the vital organs.

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Terms in this set (30)

Alpha 1

Alpha 2

Inhibits the release of norepinephrine, dilates the blood vessels, produces hypotension, decreases gastrointestinal motility and tone.
Alpha 2 receptors are found in the postganglionic sympathetic nerve endings. They inhibit the release of norepinephrine, which leads to a decrease in vasoconstriction... this results in vasodilation and a decrease in BP.

Beta 1

Increases the heart rate and force of contraction, increases renin secretion which increases blood pressure.

Beta 1 receptors are located in the kidney but primarily in the heart. When stimulated, these receptors increase myocardial contractility and heart rate.

Negative effect: dysthymias, angina

Beta 2

Dilates bronchioles, promotes gastrointestinal and uterine relaxation, promotes increase in blood sugar through glycogenolysis in the liver, increases blood flow in the skeletal muscles.

Beta 2 receptors are mostly in the smooth muscle of the lungs and gastrointestinal tract, liver and uterine muscle. Stimulation of beta 2 receptors = relations of smooth muscles of lungs (bronchodilation), decrease in gastrointestinal tone and motility and activation of glycogenolysis in the liver and increased blood glucose as well as relaxation of the uterine muscles resulting in a decrease in uterine contraction.

negative effect: hyperglycemia in diabetic person, tremor.

Explain how drugs that stimulate the sympathetic nervous system work..

Drugs that stimulate the sympathetic nervous system are called : adrenergics, adrenergic agonists or sympathomimetics because they mimic the sympathetic neurotransmitters norepinephrine and epinephrine. These act on adrenergic receptor sites located in the effector cells of the muscles, such as the heart, bronchiole walls, gastrointestinal tract and urinary bladder and cilliary muscle of the eye.