Conduction System of Heart

Question 1

What electrolytes are active in the heart?

Answer 1

Sodium and Potassium

Question 2

Where is the SA node located?

Answer 2

right atrium

Question 3

SA Node Function

Answer 3

• brain talks to heart
• electrical conduction that helps with heartbeat comes down here
• pacemaker of heart that starts the beats

Question 4

What happens if there are no SA nodes?

Answer 4

heart would beat slower

Question 5

Where does the signal from the SA node go and what does it do?

Answer 5

the atria which is caused to contract and then AV Node

Question 6

AV NODE (AtrioVentricular Node in between atria and ventricle)

Answer 6

sends the signal down the ventricular septum into the Bundle of HIS

Question 7

Bundle of His sends signal to?

Answer 7

left bundle branch and right bundle branch

Question 8

Purkinje Fibers

Answer 8

Small signal fibers that disperse the signal from the left & right bundle branches and activate the muscles in the ventricles at the same time

Question 9

P Wave

Answer 9

Atrial depolarization
- atria are contracting

Question 10

QRS Complex

Answer 10

Ventricular depolarization
- Ventricles contraction

Question 11

What does a QRS complex look like?

Answer 11

Higher wave because there is more muscle which means more electricity

Question 12

T Wave

Answer 12

• Ventricular Repolarization
• Ventricles resetting to be able to contract again

Question 13

What is systolic pressure on an EKG?

Answer 13

PQRST

Question 14

What is diastolic pressure on an EKG?

Answer 14

Disostic is everything outside of PQRST - it lasts longer & takes up more of the EKG

Question 15

Cardiac Output

Answer 15

volume pumped by left ventricle in 1 minute

Question 16

Formula for Cardiac Output

Answer 16

CO = HR * SV
CO - cardiac output
HR - heart rate (beats/minute)
SV - Stroke Volume

Question 17

End-diastolic volume

Answer 17

the amount of blood that is in the ventricles before the heart contracts

• point where there is most volume

Question 18

End systolic Volume

Answer 18

End-systolic volume is the volume of blood in a ventricle at the end of contraction

• point where there is least volume

Question 19

Stroke Volume Formula

Answer 19

EDV - ESV

Question 20

Preload

Answer 20

the amount of stretch in the heart’s ventricles just before they contract

Question 21

What is preload determined by?

Answer 21

determined by the volume of blood returning to the heart (end-diastolic volume, EDV)

Question 22

What causes an increase in stroke volume?

Answer 22

An increase in venous pressure leads to an increase in EDV, which in turn increases the stretch on the heart muscle.

• This increased stretch allows the heart to contract more forcefully, leading to an increase in stroke volume.

Question 23

Afterload

Answer 23

the resistance the heart must overcome to eject blood into the systemic circulation

Question 24

What is afterload determined by?

Answer 24

arterial (aortic) pressure

Question 25

What causes a decrease in stroke volume?

Answer 25

An increase in afterload, such as high arterial pressure, leads to increased resistance for the heart to pump blood out, resulting in a decrease in stroke volume.

Question 26

Contractility

Answer 26

refers to the strength of the heart’s contraction