Flashcards in Cardiac Quiz Deck (118)
What two factors determine mean arterial blood pressure?
1) CO (HR x SV)
What two factors determine cardiac output?
CO= SV x HR
The interplay of what 3 factors determine stroke volume?
What two factors determine preload?
1) intravascular volume
2) venous tone
* when veins constrict, blood is diverted to the heart
What is the major determinant of intravascular volume?
the amount of sodium in the body
What hormone is most important for controlling intravascular volume?
aldosterone--> controls the Na+
What is the best equation for MAP if you know CO and SVR?
MAP = (CO x SVR)/80 + CVP
*this equation can be manipulated to find other values
Preload is the ________ present in the wall of the left ventricle at the end of diastole (immediately prior to contraction).
tension--> "tightness"--> force
*preload is d\t volume, but is not volume--> it is the tension in the wall
Preload is determined by the _______ of blood in the LV chamber at the end-diastole.
VOLUME--> but it is the tension not volume
Afterload is the _______ in the wall of the heart at the time the ______ valve opens.
tension--> force at the time the aortic valve opens
* "After"load--> after systole starts
Afterload is determined by ___________.
SVR...... SVR= PRESSURE
* the > the SVR, the > the afterload
* afterload is d\t the SVR (pressure) on the other side of the valve but is actually the tension on the wall after systole begins
The _______ the SVR, the _______ the afterload.
When afterload increases, SV _______.
When preload increases, SV ________.
The > the ventricular filling (volume), the ________ the preload (tension). What explains this?
greater--> this is d\t Frank Starlings Law of the Heart
Where _____ goes, H2O follows.
When you hear preload think _______, afterload think _______, contractility think ________.
contractility=chemicals (inotropes, CCB's, etc)
SV= _______ - _______.
EF= (EDV-ESV)/EDV x 100
Contractility doesn't influence _______, it influences ______.
filling--> it influences emptying
Where does angiotensinogen come from?
Where does renin come from?
the kidney (JGA); its dumped into the blood and affects angiotensinogen--> Ang1
Where is angiotensin converted enzyme (ACE) primarily found and what does it do?
LUNGS--> converts angiotensin I to II
Anytime you see "-ogen" as in angiotensinogen, think ______.
How can you easily remember the layers and products of the adrenal cortex?
AG (aldosterone--> zona glomerulosa)
CF (cortisol--> zona fasiculata) (glucocorticoids such as cortisol)
TR (testosterone--> zona reticularis)
*remember--> salt, sugar, sex (aldosterone, cortisol, testosterone)
Given you have filled the heart (preload) and that the aortic valve opens (afterload), can you squeeze better? This is contractility. It is determined by the CHEMICAL environment of the cardiac cell. What are some examples of chemicals that alter contractile function?
ions (calcium and magnesium), oxygen, acids, drugs, hormones
*when contractility increases, the ventricle empties MORE completely and SV increases
What is the difference between concentric and eccentric hypertrophy in relation to the size of the left ventricular chamber?
concentric= no change in the size of the LV chamber
eccentric= increased size of the LV chamber
What law has to do with ventricular hypertrophy in response to pressure or volume overload?
law of Laplace
What happens during concentric hypertrophy?
LV wall thickens and chamber size remains same--> results from chronically elevated afterload (coarctation of aorta, chronic aortic stenosis, chronic untreated arterial HTN)
*IHSS is different than concentric hypertrophy b\c size of LV chamber would decrease