3.2.2. Adrenergics I and II Flashcards
Norepinephrine acts on which types of adrenergic receptors?
- alpha 1, alpha 2
- beta 1
Epinephrine acts on which types of adrenergic receptors?
- alpha 1, alpha 2
- beta 1, beta 2, beta 3
Dopamine (1st cousin of the adrenergic receptor) acts on which types of adrenergic receptors?
- beta 1
- D1 (and D5), D2 (and D3 & D4)
Which adrenergic receptors are found in the heart?
beta 1
What is the response to adrenergic agonists in the heart?
-increased contractility, increased automaticity, increased conduction velocity (remember these are beta 1 receptors)
Which adrenergic receptors are found in blood vessels?
- alpha 1 (in most vascular beds)
- beta 2 (in skeletal muscle & liver)
- D1, dopamine, in kidney and mesentery
On smooth muscle, what do alpha 1 receptors mediate?
How about beta 2 receptors?
Alpha 1 mediates constriction on smooth muscle, beta 2 mediates relaxation.
What is the response to adrenergic agonists in blood vessels?
- arteriolar constriction (alpha 1 in most vascular beds)
- arteriolar dilation (beta 2 in skeletal muscles and liver, and D1 in kidney and mesentery)
- venoconstriction (alpha 1)
- venodilation (beta 2)
Which adrenergic receptor is found in bronchioles?
beta 2
What is the response to adrenergic agonists in the bronchioles?
Dilation (remember beta 2 mediates relaxation)
Which adrenergic receptor is found in the iris?
alpha 1
What is the response to adrenergic agonists in the iris?
radial muscle contraction (mydriasis–remember alpha 1 constricts)
Which adrenergic receptors are present in the GI tract and urinary bladder?
- alpha 1
- beta 2
What is the response to adrenergic agonists in the GI tract and urinary bladder?
- contraction of the sphincters (alpha 1)
- decreased motility (beta 2)
Which adrenergic receptor is found in the uterus?
beta 2
What is the response to adrenergic agonists in the uterus?
relaxation (beta 2)–> we give beta 2 agonist to slow labor
Beta 1 is only found in these three places:
heart, fat and kidney
Which adrenergic receptor is NEVER found at a synapse?
beta 2 (beta 2 is extra-junctional on end organs and beta 2 receptors are activated by circulating EPI)
What are the metabolic effects of beta 2 and alpha 1?
stimulate glucose release from liver
What are the metabolic effects of beta 1 and beta 3?
stimulate free fatty acid release from fat cells
True or False: EPI increases all aspects of cardiac activity
True (cardiac effects of EPI (beta 1 actions) include: increased automaticity, increased heart rate, increased conduction velocity, increased contractile force, increased cardiac output and O2 consumption
What is the effect of a low dose of EPI on HR, BP and peripheral resistance?
HR increases (beta 1), diastolic pressure decreases (beta 1) and increase in systolic pressure (alpha 1 & beta 2), peripheral resistance decreases (alpha 1 & beta 2)
What is the effect of EPI on the bronchioles?
bronchioles dilate (beta 2)
What are the metabolic effects of EPI?
EPI increases the availability of glucose and fatty acids for the skeletal muscle.
What is the effect of norepinephrine on HR, BP and peripheral resistance?
HR decreases (alpha 1 and beta 1), diastolic BP increases (alpha 1) and systolic blood pressure increases (beta 1), peripheral resistance goes way up (alpha 1)
What is the effect of isoproterenol on HR, BP and peripheral resistance?
BP slightly lowered, HR increased (beta 1), peripheral resistance decreased (beta 2) (*isoproterenol stimulates beta 1 and beta 2 but not alpha receptors)
What is the effect of dopamine on HR, BP and peripheral resistance?
BP slightly elevated, HR slightly increased, peripheral resistance slightly lowered
Which agents have an affinity for alpha 1 receptor (found in arterial smooth muscle)?
EPI>/=NE»I
Which agents have an affinity for beta 1 receptor (found in the heart)?
I>EPI=NE