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RENIN ANGIOTENSIN PATHWAY

Terms in this set (53)

What are the two most important fluids to keep in balance?
blood volume and ICF
The most critical fluid to keep in balance and prevent death is ?
maintaining blood volume (intravascular) at a sufficient level for blood pressure to remain high enough ensure adequate perfusion and oxygenation of all organs and tissuesl.
Which organ is the major regulator of water and Na balance to maintain blood pressure and perfusion to all tissues and organs?
Kidney
The kidneys are the major regulator of water and Na to maintain blood pressure and perfusion to all tissue and organs; they monitor the following:
blood pressure, blood volume, blood Na (osmolarity) and blood oxygen
What are conditions that signal to the kidneys that there is decreased tissue perfusion?
lw BP, low Voume, low Na, low O2
When the kidneys sense there is decreased tissue perfusion, they secrete the substance called :
RENIN
WHAT DOES RENIN DO?
sets into motion a group of HORMONAL and BLOOD VESSEL responses to ensure that blood vessel responses to ensure that blood pressure is raised back up to normal.
LOW BLOOD PRESSURE TRIGGERS RENIN RELEASE B/C:
when it gets too low, blood cannot flow through vessels into tissues and organs
LOW BLOOD VOLUME TRIGGERS RENIN RELEASE B/C:
it is directly related to blood pressure; anything that reduces blood volume, ex. Dehydration or Hemorrhage below a critical level, ALWAYS lowers blood pressure.
LOW OXYGEN TRIGGERS RENIN RELEASE B/C:
with too little oxygen in the blood, even if the blood reaches the tissues and organs, it cannot supply the needed oxygen and the tissues and organs can die.
LOW BLOOD Na TRIGGERS RENIN RELEASE B/C:
Na and water are closely linked. where Na goes, water follows. so anything the blood to have too little Na prevents water from staying in the blood. the result is low blood volume, with low blood pressure, and poor tissue perfusion.
DEFINITION OF RENIN:
IT IS AN ENZYME THAT ACTIVATES SOME BLOOD PROTEINS, ONE OF WHICH IS ANGIOTENSIN. ACTIVATED ANGIOTENSIN IS ANGIOTENSIN 1, WHICH IS RELATIVELY WEAK AND HAS LITTLE ACTION. ANGIOTENSIN 1 IS THEN ACTED ON BY ABOTHER ENZYME KNOWN AS ANGIOTENSIN CONVERTING ENZYME (ACE) WHICH CONVERTS ANGIOTENSIN 1 TO ANGIOTENSIN 2 , THE MOST ACTIVE FORM.
IS RENIN A HORMONE OR AN ENZYME?
ENZYME
WHAT DOES ANGIOTENSIN CONVERTING ENZYME (ACE) DO?
it converts Angiotensin 1 to Angiotensin 2
3 ACTIONS OF ANGIOTENSIN 2:
1. VASOCONSTRICTOR: it causes constriction of small arteries & veins which increases peripheral resistance and reduces the size of the vascular bed, which RAISES BLOOD PRESSURE W/OUT ADDING MORE BLOOD VOLUME.
2. LOWERS GLOMERULAR FILTRATION- it constricts the size of the arterioles that feed the kidney nephrons, which results in a HUGE REDUCTION OF URINE OUTPUT. decreasing urine output prevents further loss of water so that more is retained in the blood to help raise blood pressure.
3. causes the Adrenal Glands to release ALDOSTERONE "water and sodium saving hormone" b/c it causes the kidneys to reabsorb water and Na preventing them from being excreted into the urine. this response allows more water and sodium to be returned to the blood , increasing BP and Blood Volume.
ALL OF THESE ACTIONS MAINTAIN PERFUSION TO VITAL ORGANS
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