Cardiovascular System Lecture 3

Question 1

What is Systole?

Answer 1

Systole – cardiac muscle cell contraction

Question 2

What is Diastole?

Answer 2

Diastole – cardiac muscle cell relaxation

Question 3

Listen in Class?

Answer 3

99% cardiac muscle cells:
* Contractile fibers.
* Electric impulse arrives – respond by
generating muscle systole.

1% cardiac muscle cells:
* Form a conduction system (yellow)
controlling generation and movement of
electric impulse through heart.
* Form and send electric impulse to 99%
that are contractile cardiac muscle cells.

Question 4

What is Resting Potential?

Answer 4

• Membrane potential prior to stimulation.
• -70 mV means inside of the cell is more negative than the outside by this amount.

Question 5

What is an Action potential?

Answer 5

• If a stimulus reaches a threshold (-55 mV in this case) will initiate an action potential:

Question 6

What is Depolarization?

Answer 6

membrane potential becomes less negative relative to resting potential

Question 7

What is Repolarization?

Answer 7

membrane potential returns to resting potential after depolarization

Question 8

Draw Action Potential Graph
(MC - Know where each step is)

Answer 8

Question 9

What generates Action Potentials in the heart?

Answer 9

The Sinoatrial (SA) node:
* Acts as “pacemaker” for heart; generates action potentials
* No steady resting potential.
* A slow depolarization (pacemaker potential) brings to threshold where APs are generated

Question 10

Where is the SA node?

Answer 10

right atrium

Question 11

What does it mean for a cell to be autorhythmic?

Answer 11

Cardiac muscle cells are autorhythmic meaning they can generate electric impulse without outside influence

SA node becomes dominant in this function

Question 12

What is Ectopic focus?
What Triggers it?

Answer 12

signal not starting in the SA node

common triggers:
anxiety, lack of sleep, excess caffeine, nicotine, alcohol)

Question 13

What is Atrial Systole?

Answer 13

Atrial systole is the phase of the cardiac cycle when the atria contract to push blood into the ventricles.

Question 14

What happens during Atrial Contraction?

Answer 14

The electrical signals generated in the SA node travel through the atrial muscle cells, causing them to contract, and because the atrial muscle cells are connected, the signal spreads quickly, making it seem like the atria contract simultaneously without needing the conduction system’s continuous guidance.

Question 15

Where is the AV node?

Answer 15

Question 16

What is ventricular contraction?

Answer 16

Ventricular contraction, or ventricular systole, occurs when the ventricles contract to pump blood out of the heart and into the circulatory system.

Question 17

Why is there a delay of approximately 0.1 seconds at the AV node?

How do action potentials (APs) progress in the ventricles after the AV node delay?

Answer 17

There is a delay at the AV node to provide time for atrial systole to finish before the onset of ventricular systole.

Following the delay at the AV node, APs travel down the AV bundle, which then divides into bundle branches that enter the ventricles

Question 18

What is the role of Purkinje fibers in the cardiac conduction system?

Answer 18

Purkinje fibers lead the way by propagating APs to ventricular contractile muscle cells, ultimately triggering ventricular systole.

Question 19

What distinguishes atrial action potentials (APs) from ventricular action potentials (APs)?

Answer 19

The primary differences between atrial and ventricular APs lie in the timing of events and the width of the plateau phase

Question 20

What is an Electrocardiogram?

Answer 20

Electrocardiogram (ECG): Combine all individual APs of atria and ventricles together
– generates a flow of electrical current in extracellular fluid

Question 21

What are the Vertical and Horizontal Components of an ECG?

Answer 21

Amplitude (mV) – vertical component

Duration (msec) – horizontal component

Question 22

What is a P wave?

Answer 22

P wave – atrial depolarization

Question 23

What is the QRS Complex?

Answer 23

QRS complex (Q, R, and S waves) –
ventricular depolarization (includes atrial repolarization).

Question 24

What is the T wave?

Answer 24

T wave – ventricular repolarization

Question 25

What are the Segments on the ECG?

Answer 25

Segments – periods between waves

Question 26

What is the PR segment?

Answer 26

PR segment – AV nodal delay.

Question 27

What is the ST Segment?

Answer 27

ST segment – ventricular systole
and ejection

Question 28

What is the TP segment?

Answer 28

TP segment – ventricular diastole
and filling.

Question 29

Answer 29

Question 30

What is Arrhythmias?

Answer 30

Arrhythmias are abnormal heart rhythms characterized by irregular or erratic electrical activity in the heart, potentially leading to heart palpitations, dizziness, and other cardiac issues.

Question 31

What is wrong?
(What is missing?)

Answer 31

Question 32

What is wrong?
(What is missing?)

Answer 32

Question 33

What is wrong?

Answer 33

Question 34

What is the Cardiac cycle?

Answer 34

• Events associated with a single heart beat.
• Broken into phases named for ventricular events.

Question 35

What is Ventricular systole?

Answer 35

• Ventricular contraction and ejection.
• 2 parts – isovolumetric contraction / ventricular ejection.

Question 36

What is Ventricular diastole?

Answer 36

• Ventricular relaxation and filling.
• 3 parts – isovolumetric relaxation / ventricular filling prior to atrial systole / ventricular filling during atrial systole

Question 37

Random times idk just memorize it 🦧

Answer 37

• 75 bpm (average heart rate)
• cardiac cycle 0.8 sec.
• Ventricular: systole 0.3 sec/diastole 0.5 sec
• Atrial: systole 0.1 sec / diastole 0.7 sec