Baroreceptor reflex

Baroreceptor: ↑ blood pressure → activate stretch receptors → CNS → autonomic efferents → ↓ BP.  Origins:
Aortic arch wall → efferent via vagus → tractus solitarius in medulla
Carotid sinuses (above carotid bifurcation in internal carotid) → small Hering’s nerves → glossopharyngeal nerve → tractus solitarius

Reflexes:
For low blood pressure:
Alpha-1 receptors → vasoconstriction
Both arteries (↑ SVR) and veins (↑ blood return to heart)
Beta-1 receptors → increase cardiac activity
For high blood pressure:
Inhibit vasoconstriction center in medulla → ↓ peripheral resistance
Parasympathetic muscarinic receptors → ↓ HR and mildly ↓ cardiac contractility → ↓ CO