2 - Cardiovascular I Flashcards
What percentage of blood is in arteries at any given time?
What percentage is in veins?
Only 20% is in arteries
64% of the blood is in veins, venules, and venous sinuses
What is systemic filling pressure?
The force returning blood to the heart
Think of it as the degree to which blood is returning to the heart
Normal is about 7 mmHg. Constriction of veins increases the SFP, increasing the amount of blood returning to the heart
If the EF of the LV is 45%, what is the EF of the RV?
In a normal heart, they are always the same
What determines arterial pressure?
Peripheral resistance x CO
An increase in either peripheral resistance or Cardiac Output will increase BP
Under normal circumstances, Arterial Pressure is regulated by three systems:
In abnormal circumstances it is regulated by four:
The ANS
RAAS
Kidneys
Also controlled by natriuretic peptides in abnormal situations
ANP is produced by:
BNP is produced by:
CNP is produced by:
ANP: myocytes of the atria
BNP: myocytes of the ventricles (and a little bit in the brain)
CNP: cells of the vascular endothelium
What do ANP and BNP do?
- Increase vascular permeability - moves fluid out of vasculature and into interstitial spaces
- Cause diuresis and Natriuresis in the Kidney
- Dilate arterioles and veins by suppressing SNS output from the CNS
Diuretics work primarily by interfering with _______
Reabsorption
Most diuretics share the same basic MOA:
blockade of sodium and chloride reabsorption
The increase in urine flow that a diuretic produces is directly related to:
the amount of sodium and chloride reabsorption that it blocks
Furosemide MOA
Blocks Na and Cl reabsorption in the Thick Ascending, preventing passive reabsorption of water
Why is Lasix helpful in patients with severe renal failure?
Unlike thiazides, it can promote diuresis even when RBF and GFR are low
What kind of diuretic should be used in a patient taking digoxin?
Potassium sparing
Name the four loop diuretics:
Lasix
Ethacrynic acid
Bumetanide
Torsemide
What is the MOA of Hydrochlorothiazides?
blocks reabsorption of Na and Cl in the early segment of the distal tubule
What is the primary indication for Hydrochlorothiazide?
Essential HTN
What class of diuretics is spironolactone in?
potassium sparing Aldosterone antagonists
What is the MOA of spironolactone?
Blacks the actions of aldosterone in the distal nephron