Study Set Content:
The action of sympathomimetics on the central nervous system varies dramatically, depending on their ability to cross the
blood-brain barrier
These effects have been described as ranging from ___ to ____ or "a feeling of impending disaster."
"nervousness", "an adrenaline rush
Peripheral effects of B-adrenoceptor agonists such as tachycardia and tremor are similar to the somatic manifestations of
anxiety.
Noncatecholamines with indirect actions, such as amphetamines, which readily enter the central nervous system from the circulation, produce qualitatively very different
CNS effects
Endogenous Catecholamines
• Epinephrine (adrenaline) is an agonist at both a and ß receptors. It is therefore a very potent
vasoconstrictor and cardiac stimulant.
The rise in systolic blood pressure that occurs after epinephrine release or administration is caused by its ____ on the heart (predominantly B1 receptors) and the vasoconstriction induced in many vascular beds (a receptors).
positive inotropic and chronotropic actions
also activates B 2 receptors in some vessels (eg, skeletal muscle blood vessels) leading to their dilation leading to their dilation. .
Epinephrine
(levarterenol, noradrenaline) is an agonist at both a 1 and a 2 receptors.
Norepinephrine
Norepinephrine also activates B 1 receptors with similar potency as epinephrine, but has relatively little effect on
B 2 receptors.
increases peripheral resistance and both diastolic and systolic blood pressure.
Norepinephrine
is the immediate precursor in the synthesis of norepinephrine
Dopamine
Endogenous dopamine may have more important effects in regulating (blank)and (blank)
sodium excretion, renal function.
It is an important neurotransmitter in the central nervous system and is involved in the reward stimulus relevant to addiction.
Dopamine
Its deficiency in the basal ganglia leads to Parkinson's disease, which is treated with its
precursor levodopa
Dopamine receptors are also target for
antipsychotic drugs
is an effective mydriatic and decongestant and can be used to raise the blood pressure
Phenylephrine
Epinephrine
➢ Stimulates
a,. 02. B1. B2 receptors
At low dose-epinephrine stimulates
b1 and b2 receptors
At high doses - it stimulates
a receptors.
Cardiovascular effect :() heart rate & contractility: () of arterioles in the skin, viscera, & mucous membrane.
increased, vasoconstriction
