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i ^sponse to Decreased ECF

RENAL PHYSIOLOGY

T

Volume contraction

1

| Renin

Sympathetic

activity

| Angiotensin I

f Angiotensin II

J. Perkins

MS, MFA

°(py

Ficure 6.14 Response to Volume Contraction_

' -e kidneys respond to a decrease in the volume of the extracellular <j (volumc contraction) by dccreasing their excretion of NaCI and »jtcr. The primary mechanisms m this response aro summarized. Vcreased NaCI excretion rcsults from a decrease in the filtered loatl NaCI (decreased OK) and stimulation of NaCI reabsorption along -*• nephron. This occurs because the sympathetic and renin-• -ąiotensin-aldosterone Systems are activated and atrial natriuretic peptide (ANP) secretion is suppressed. The sympathetic and renin-angiotensin-aldosterone Systems decrease the GFR and stimulate proximal tubule and collecting duet NaCI reabsorption. Increased levels of antidiuretic hormone (ADH) cause decreased water excre-tion. Abbreviation: ACt, Angiotensin<onvcrting enzyme.

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