Cardiovascular System Lecture 3 Flashcards
What is Systole?
Systole – cardiac muscle cell contraction
What is Diastole?
Diastole – cardiac muscle cell relaxation
Listen in Class?
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.
What is Resting Potential?
- Membrane potential prior to stimulation.
- -70 mV means inside of the cell is more negative than the outside by this amount.
What is an Action potential?
- If a stimulus reaches a threshold (-55 mV in this case) will initiate an action potential:
What is Depolarization?
membrane potential becomes less negative relative to resting potential
What is Repolarization?
membrane potential returns to resting potential after depolarization
Draw Action Potential Graph
(MC - Know where each step is)
What generates Action Potentials in the heart?
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
Where is the SA node?
right atrium
What does it mean for a cell to be autorhythmic?
Cardiac muscle cells are autorhythmic meaning they can generate electric impulse without outside influence
SA node becomes dominant in this function
What is Ectopic focus?
What Triggers it?
signal not starting in the SA node
common triggers:
anxiety, lack of sleep, excess caffeine, nicotine, alcohol)
What is Atrial Systole?
Atrial systole is the phase of the cardiac cycle when the atria contract to push blood into the ventricles.
What happens during Atrial Contraction?
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.
Where is the AV node?
What is ventricular contraction?
Ventricular contraction, or ventricular systole, occurs when the ventricles contract to pump blood out of the heart and into the circulatory system.
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?
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
What is the role of Purkinje fibers in the cardiac conduction system?
Purkinje fibers lead the way by propagating APs to ventricular contractile muscle cells, ultimately triggering ventricular systole.
What distinguishes atrial action potentials (APs) from ventricular action potentials (APs)?
The primary differences between atrial and ventricular APs lie in the timing of events and the width of the plateau phase
What is an Electrocardiogram?
Electrocardiogram (ECG): Combine all individual APs of atria and ventricles together
– generates a flow of electrical current in extracellular fluid
What are the Vertical and Horizontal Components of an ECG?
Amplitude (mV) – vertical component
Duration (msec) – horizontal component
What is a P wave?
P wave – atrial depolarization
What is the QRS Complex?
QRS complex (Q, R, and S waves) –
ventricular depolarization (includes atrial repolarization).
What is the T wave?
T wave – ventricular repolarization
What are the Segments on the ECG?
Segments – periods between waves
What is the PR segment?
PR segment – AV nodal delay.
What is the ST Segment?
ST segment – ventricular systole
and ejection
What is the TP segment?
TP segment – ventricular diastole
and filling.
What is Arrhythmias?
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.
What is wrong?
(What is missing?)
What is wrong?
(What is missing?)
What is wrong?
What is the Cardiac cycle?
- Events associated with a single heart beat.
- Broken into phases named for ventricular events.
What is Ventricular systole?
- Ventricular contraction and ejection.
- 2 parts – isovolumetric contraction / ventricular ejection.
What is Ventricular diastole?
- Ventricular relaxation and filling.
- 3 parts – isovolumetric relaxation / ventricular filling prior to atrial systole / ventricular filling during atrial systole
Random times idk just memorize it 🦧
- 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
