Sympathetic Nerve Effects

An increase in sympathetic nerve activity, as occurs during the fight-or-flight reaction and exercise, stimulates constriction of afferent arterioles. This helps to preserve blood volume and to divert blood to the muscles and heart. A similar effect occurs during cardiovascular shock, when sympathetic nerve activity stimulates vasoconstriction. The decreased GFR and the resulting decreased rate of urine formation help to compensate for the rapid drop of blood pressure under these circumstances (fig. 17.11).

Table 17.1 Regulation of the Glomerular Filtration Rate (GFR)

Regulation Stimulus

Afferent Arteriole

Sympathetic Activation by Constricts Decreases nerves baroreceptor reflex or by higher brain centers Autoregulation Decreased blood Dilates No change pressure

Autoregulation Increased blood Constricts No change pressure

Was this article helpful?

0 0
Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Post a comment