Physiology Cardio

Question 1

the cardiac output determinants

Answer 1

1-preload
2-afterload
3-contractility
4-heart rate

Question 2

EDV
ESV

Answer 2

EDV: end diastolic volume : the filling is completed and the contraction is beginning
ESV: systolic volume : emptying is completed and the relaxation is beginning

Question 3

stroke volume

Answer 3

EDV-ESV : the amount of blood pushed out of the left ventricule in each heartbeat
-affected by Contractility , After load and Preload

Question 4

cardiac output

Answer 4

CO=SV x HR
-SV : stroke volume
-HR : heart rate
-the more cardiac output means more work and more O2

Question 5

pulse pressure

Answer 5

PP=SBP-DBP
-PP is directly proptional to SV ( SBP is determined by SV )
- PP is inversly proportional to arterial compliance ( DBP is determined by TPR )

Question 6

MAP = Mean arterial pressure

Answer 6

MAP = CO x TPR =2/3 DBP + 1/3 SBP = DBP + 1/3PP
-estimate the afterload

Question 7

Ejection Fraction

Answer 7

SV/EDV
- Index of ventricular contactility : normal 55 to 60%
- % of blood pushed out of the left ventricle
- low in systolic heart failure
- normal in diastolic heart failure

Question 8

Preload

Answer 8

amount of blood loaded into the left ventricule (present before contraction )
determined by LVEDV (difficult) or LVEDP (easier)

Question 9

to increase preload

Answer 9

1- add volume
2-slow heart rate
3-constrict veins (sympathetic stimulation )

Question 10

to decrease preload

Answer 10

1-remove volume
2-raise heart rate
3-pool blood in veins (vasodilatation

less work of heart so we can try to decrease preload to relive angina

Question 11

Afterload

Answer 11

forces resisting flow out of left ventricle

Question 12

to increase afterload

Answer 12

1- raise mean blood pressure ( MAP and TPR )
2-obstrut outflow of left ventricle ( case of aortic stenosis and HCM )

Question 13

to decrease afteload

Answer 13

1-lower the MAP (vasodilators )
2-treat aortic valve disease

Question 14

increase afterload effect on Left ventricle

Answer 14

LV compensates for high afterload by thickening (hypertrophy) in order to decrease wall stress.
-chronci hypertension (High MAP ) leads to LV hypertrophy

Question 15

heart rate and CO relation under artificial conditions

Answer 15

CO=SVxHR
hight HR leads to decrease Stoke volume because of less filling time
but still the increase heart rate is much greater than the drop of SV this is why CO is increased

Question 16

heart rate and CO under physiologic conditions

Answer 16

CO=SVxHR
hight HR leads to decrease Stoke volume because of less filling time BUT the heart rate increases the contractility that increases SV so high HR means high SV and high CO

Question 17

pathologic high heart rate and CO

Answer 17

high heart rate with arrhythmia (300beats/min) leads to decreases Cardiac Output
because the SV drops dramatically

Question 18

myocardial O2 demand is increased by :

Answer 18

increase :
-contractility
-afterload
-heart rate
-diameter of ventricle ( wall tension )