Regulation of Fluid Balance

What 3 hormones control fluid & electrolyte balance?

-Aldosterone

-ADH

-Natriuretic Peptide (NP)

What is aldosterone?

A hormone secreted by the adrenal cortex whenever sodium levels in the extracellular fluid (ECF) are low.

What does Aldosterone prevent?

Water and sodium loss

What happens when aldosterone is secreted?

It acts on the kidney nephrons, and triggers them to reabsorb sodium and water from the urine back into the blood

How does the secretion of Aldosterone affect the blood osmolarity & blood volume?

It INCREASES THE BLOOD OSMOLARITY & BLOOD VOLUME

What electrolyte does aldosterone promote the excretion of?

Potassium

What is the other name for ADH?

Vasopressin

Where and why is ADH/Vasopressin released?

Released from posterior pituitary gland in response to changes in blood osmolarity

How is the hypothalamus related to regulation of fluid balance?

The hypothalamus contains osmoreceptors, which are sensitive to changes in blood osmolarity.

How does ADH trigger?

Increased blood osmolarity, especially an increase in level of plasma sodium, results in slight shrinkage of these cells & triggers ADH release from the posterior pituitary gland

What does ADH act on?

Kidney nephrons. This makes them more permeable to water. As a result, more water is reabsorbed by these tubules and returned to blood, which decreases blood osmolarity by making it more dilute.

What INHIBITS ADH release?

Blood osmolarity decreasing, and low plasma sodium levels which causes the osmoreceptors to swell slightly

What are Natriuretic peptides?

Hormones secreted by special cells that line the atria and ventricles of heart

What are NPs secreted in response to?

Increased blood volume and blood pressure, which stretch the heart tissue.

What do NPs bind to?

Receptors in kidney nephrons

Are the effects of NPs bindings similar or opposite of aldosterones effects?

OPPOSITE