fluid homeostasis

vasopressin

Known also as ADH or Vasostrict

drug used to:

• increase blood volume

• decrease urine output

diabetes insipidus & vasopressin

when kidneys can not properly concentrate urine

septic shock & vasopressin

vasopressor (constricts blood vessels) which improves organ perfusion

xxx and vasopressin

how does ADH affect renal tubular water movement

ADH binds to its membrane receptor (which is a GPCR, specifically G-aS)

apical side vs basal side

apical side - faces the lumen (open space)

basal side - the other side :)

The Renin-Antiotensin-Alsosterone System

critical regulator of blood pressure, electrolyte balance, and systemic vascular resistance

what is renin

an enzyme secreted into blood by kidneys following a drop in blood pressure of fluid volume

what is angiotensinogen

secreted by liver

what renin cleaves

what is the pathway to get to angiotensin II

1. angiotensin is released from the liver

2. renin released from kidneys when low BP or drop in fluid volume

3. renin cleaves angiotensinogen → angiotensin I

4. ACE (angiotensin-converting enzyme) released from lungs

5. ACE cleaves angiotensin I → angiotensin II

6. angiotensin II goes to blood vessels and adrenal corte

what is angiotensin II

the active form of the molecule which circulates to:

• blood vessels: directly stimulates vasoconstriction

• adrenal cortex: stimulate release of aldosterone which acts on kidneys to stimulate reabsorption of water

what is aldosterone

critical modulators of gene expression during water conservation

secreted by adrenal cortex when blood pressure is low

steroid hormone that binds to nuclear receptors which change gene expression

what happens when aldosterone binds to its nuclear receptor?

increases the synthesis of Na/K pumps (mobilized to the basal membrane) and the Na antiporters (mobilized to apical membrane facing the lumen)

These new transport proteins:

• increase secretion of K+

• increase absorption of Na+ and water

Water travels with Na+ due to osmotic pressure changes

Increased water retention increases blood pressure

ACE inhibitors

class of medication used for treatment of high blood pressure and heart failure

• they inhibit the activity of angiotensin-converting enzyme (which converts angiotensin I to angiotensin II)

used to treat

• acute myocardial infarction (heart attack)

• heart failure (left ventricular systolic dysfunction)

• high blood pressure associated w/ diabetes millitus (diabetic nephropathy) by means of decreasing the blood pressure and increasing perfusion in glomerular arterioles

Atrial natriuetic hormone (ANH)

a hormone secreted by the cells in the right atrium when they are stretched higher than usual

ANH is also called ANP (atrial natriuretic peptide) and functions opposite of ADH)

when is ANH released

when blood pressure of volume increases

• detected by mechanoreceptor in the right atria