10. Cardiac Cycle

Question 1

what do EKGs show

Answer 1

electical events of heart - depol/repol

*electrical event happens BEFORE mechanical event (contraction)

Question 2

which wave is associated with atrial depolarization & where does it begin

Answer 2

P wave

initiated at the SA node

=atrial systole

Question 3

what is the PR interval

Answer 3

SA –> AV

Av is slower so there is a lag of depol in ventricles after atria

-this allows atria to contract & max volume into ventricles before the ventricles contract

Question 4

where is electical signal sent after the AV node

Answer 4

bundle of His –> R/L bundle banches –> purkinje fibers

Question 5

what order does the ventricle depolarize

Answer 5

1.septum –> 2. walls of both ventricles starting from apex

this order produces efficient ejection of blood out to As

Question 6

what does the QRS complex represent

Answer 6

ventricular depolarization

Question 7

what is the T wave & when does it occur

Answer 7

ventricular repol

-occurs after QRS with lag inbtn - allows time for all cardiomyocytes to be depol - get Ca2+ to M & contract

Question 8

what is the time it takes to get from one P wave to the next

Answer 8

less than 1 sec (0.8)

=around 60 bpm

Question 9

when is ventricular P lowest

Answer 9

at diastole - to create pressure gradient for blood to be pushed from atria to ventricle

Question 10

what happens to the ventricular P as you move from the P wave to the beginning of the QRS complex

Answer 10

increase slightly as the atria contracts

Question 11

when does ventricular P increase significantly

Answer 11

QRS complex

ventricle depolarize

= isovolumetric contraction (all valves are closed) & peak after ejection begins

ventricles contract

Question 12

what happens to ventricular P as ventricles repolarize (T-wave)

Answer 12

decrease

-ejecting blood out aortic/pul valve

Question 13

what is diastolic blood pressure

Answer 13

= aortic pressure when aortic valve is open

aroudn 80 mmHg

reduced P bc blood leaving aorta

Question 14

when does ventricular P drive aortic P

Answer 14

when ventricular P is above aortic and valves open to allow blood into aorta (same situation w/ pul valves)

aortic P follows ventricluar but slightly below

Question 15

what is dicrotic notch

Answer 15

as the ventricles relax the ventircular P falls below aortic P & it diverges

aortic valve closes

Question 16

what happens to the atrial P btn P & Q waves

Answer 16

atrial P increase slightly above ventricular P to create pressure gradient to force blood into ventricle

increase as th atria contract

Question 17

what happens to atrial P during isovolumic ccontraction

Answer 17

atrial P increases

ventricles contracting - all valves are closed

Question 18

what happens to atrial P when aortic/pul valves open

Answer 18

decreas quickly

-ventricle start ejecting blood

Question 19

why does atrial P gradually increase as ventricular contraction continues

Answer 19

increase gradually bc of venous return

Question 20

what happens to atrial P when AV valves open

Answer 20

atrial P decreases bc blood moves into ventricles

Question 21

what is ideal ventricular volume & how much of it is ejected at the end of diastole

Answer 21

depends on age no idea

-usually eject 60-70% of volume (never gets to 0)

Question 22

what happens to ventricular vol during the P wave

Answer 22

ventricular vol tops off

Question 23

when does ventricular vol decrease rapidly

Answer 23

when aortic/pul valve open & blood rushes out into aorta & pul trunk

Question 24

when is ventricular vol constant

Answer 24

isovolumetric contraction/relaxation

-all valves are closed

Question 25

when does ventricular volume increase

Answer 25

AV valve open rapid & then slow

Question 26

what is the a-wave

Answer 26

atrial contraction increase in jugular V pressure when atria contract after P wave - pressure reflected back to V

Question 27

What happens to jugular p during isovolumetric contraction

Answer 27

increases -all valves are closed

Question 28

what is the c-wave

Answer 28

increase in P as the isovolumetric contraction in ventricles occurs (then decreases as aortic/pul valves open) -bulging of the walls back into the atria

Question 29

what is the v-wave

Answer 29

blood returning to atria & backing up into jugular V ventricular contraction w/ AV valves closed but aortic/pul valves open blood back to heart but cant enter ventricle

Question 30

when does venous return occur

Answer 30

continously

Question 31

what is the 1st heart sound

Answer 31

closing of the AV valves as centricles contract

Question 32

what produces the 2nd heart sound

Answer 32

aortic/pul valve closing

Question 33

what sound is present as the ventricles fill rapidly

Answer 33

3rd sound heard in children (in adults with special stethescopes)

Question 34

what is the sound that is due to blood entering ventricle during atrial contraction

Answer 34

4th sound heard in children

Question 35

when does ventricular systole happen

Answer 35

QRS to beyond T -ventricular contraction

Question 36

what happens in ventriclar diastole

Answer 36

ventricular relax

Question 37

what happens to ventricular P as blood moves from atria to ventricles

Answer 37

increases

Question 38

why is atrial pressure increasing during ventricular systole

Answer 38

blood continues to return to the heart but cant get into ventricle bc the AV valves are closed

Question 39

what are two important things to note about aortic P

Answer 39

significantly above the atrial and ventricular P - a lot higher to allow efficient perfusion into body it decreases throughout atrial contraction and even into ventricular contraction

Question 40

when do AV valves close

Answer 40

when the ventricular P exceeds the atrial P prevent back flow

Question 41

what is normal aortic and pul A pressure

Answer 41

aortic P = 120/80 pul A P = 25/15 \*ventricular P must EXCEED DIASTOLIC P on each side to open the valve

Question 42

why does aortic P continue to drop throughout diastole

Answer 42

blood continues to leave aorta peripheral run - off

Question 43

what are causes of murmurs

Answer 43

blood moving backward (in direction it shouldnt) 1. systolic murmur : mitral regurgitation 2. diastolic murmur: aortic regurgitation blood having hard time moving in the direction it should (stenosis)