Adrenergic Effects

As you already know, sympathetic involves the adrenergic receptors. Let’s look at the three adrenergic receptors.

Alpha Adrenergic Receptors stimulated by norepinephrine causes…

1. Vasoconstriction. This causes an increase in blood pressure. If a person is in shock, you’d see this utilized.
2. Stimulates sweat & salivary glands (this is not the opposite of parasympathetic)
3. Decreases intra-ocular pressure (again, not the opposite of parasympathetic)

So these last two effects are not competing with the parasympathetic effects.

Beta 1 Adrenergic Receptors stimulated by norepinephrine…

Increases heart rate and the force of contraction. If a person is in shock, you’d see this utilized.

Beta 2 Adrenergic Receptors stimulated by norepinephrine causes…

Bronchodilation (useful for asthma) and can also relax smooth muscle. One potential use is to relax the uterus in case of premature labor.