Autonomic Nervous System Function and Receptor Specificity

Vocabulary flashcards covering Autonomic Nervous System (ANS) homeostatic balance, receptor specificity, and sympathetic vs. parasympathetic effects on major organ systems.

Homeostatic Balance

The maintenance of physiological stability through the dynamic, opposing actions of the sympathetic and parasympathetic nervous systems.

Receptor Specificity

The concept that the precise physiological response of target organ systems is dictated by the specific distribution and affinity of receptors.

Sympathetic Effect on the Heart ($\beta_1$ Receptor)

Increases heart rate, contractility, and conduction via $\text{cAMP}$.

Parasympathetic Effect on the Heart ($M_2$ Receptor)

Decreases heart rate and AV conduction through increased $K^+$ efflux.

Sympathetic Effect on the Lungs ($\beta_2$ Receptor)

Promotes bronchodilation.

Parasympathetic Effect on the Lungs ($M_3$ Receptor)

Promotes bronchoconstriction.

Sympathetic Effect on the GI Tract ($\alpha_1$ / $\beta_2$ Receptors)

Decreases motility and secretions while increasing sphincter tone.

Parasympathetic Effect on the GI Tract ($M_3$ Receptor)

Increases peristalsis and secretions including $\text{HCl}$ and enzymes.

Sympathetic Effect on Kidneys / Bladder System

$\alpha_1$ contracts the internal sphincter and $\beta_2$ increases relaxation of smooth muscle, leading to non-voiding.

Parasympathetic Effect on Kidneys / Bladder System ($M_3$ Receptor)

Causes smooth muscle contraction and $\text{NO}$-mediated relaxation of the internal sphincter.

Sympathetic Effect on the Eyes

$\alpha_1$ causes mydriasis, while $\beta$ increases aqueous humor production and intraocular pressure (IOP).

Parasympathetic Effect on the Eyes ($M_3$ Receptor)

Causes miosis, accommodation, and increases aqueous outflow.