2 months ago
**Similarities:** - Both are adrenergic receptors. - Both are G-protein coupled receptors. **Differences:** **Location:** - Alpha receptors in blood vessels, smooth muscles, organs. - Beta receptors in heart, lungs, liver, adipose tissue. **Subtypes:** - Alpha: alpha-1 (vasoconstriction) and alpha-2 (inhibit neurotransmitter release). - Beta: beta-1 (heart rate, contractility), beta-2 (bronchodilation, vasodilation), beta-3 (lipolysis, thermogenesis). **Response to Agonists:** - Alpha responds to norepinephrine, epinephrine (variable affinities). - Beta-1 responds to norepinephrine, epinephrine. - Beta-2 responds to epinephrine. - Beta-3 responds to norepinephrine. **Effects:** - Alpha regulates blood pressure, vascular tone, blood flow. - Beta regulates heart rate, cardiac contractility, bronchial relaxation, metabolism. **Functional Significance:** - Alpha and beta receptors work together for stress response, exercise, and quick physiological adjustments.