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Questions and Answers
The contraction, dubbed ______, is evoked by the depolarization signal.
The contraction, dubbed ______, is evoked by the depolarization signal.
systole
In the modified Lead II design, the negative and ground electrodes are placed on (or below) the right and left ______, respectively.
In the modified Lead II design, the negative and ground electrodes are placed on (or below) the right and left ______, respectively.
collarbones
The following repolarization signal leads to the relaxation of muscle cells, known as ______.
The following repolarization signal leads to the relaxation of muscle cells, known as ______.
diastole
The positive electrode is placed on the left lower part of the ______.
The positive electrode is placed on the left lower part of the ______.
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The left ventricular systole pushes a volume of blood called ______ into the aorta.
The left ventricular systole pushes a volume of blood called ______ into the aorta.
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Most important components of the ECG are the P wave, the QRS-complex, and the ______.
Most important components of the ECG are the P wave, the QRS-complex, and the ______.
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The R-peak precedes the peak of blood pressure by approximately ______ ms.
The R-peak precedes the peak of blood pressure by approximately ______ ms.
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Pulse plethysmography measurement uses near-infrared light beamed through the ______.
Pulse plethysmography measurement uses near-infrared light beamed through the ______.
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Transmission plethysmography typically measures the amount of light that passes through the ______.
Transmission plethysmography typically measures the amount of light that passes through the ______.
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The overall delay (delta T) in this case is approximately ______ ms.
The overall delay (delta T) in this case is approximately ______ ms.
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Heart rate (HR) is typically in the - domain for healthy individuals under resting conditions.
Heart rate (HR) is typically in the - domain for healthy individuals under resting conditions.
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The electrical activity of the heart is measurable using a pair of ______ placed on the surface of the skin.
The electrical activity of the heart is measurable using a pair of ______ placed on the surface of the skin.
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The activity measured by the electrodes is called ______.
The activity measured by the electrodes is called ______.
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The average interval between successive beats is called heart period or ______ interval.
The average interval between successive beats is called heart period or ______ interval.
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Multiple measures of heart rate variability (HRV) are used to estimate the ______ influence on the heart.
Multiple measures of heart rate variability (HRV) are used to estimate the ______ influence on the heart.
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Lead II refers to the placement of the positive electrode on the left ankle and the negative electrode on the ______.
Lead II refers to the placement of the positive electrode on the left ankle and the negative electrode on the ______.
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The heart pumps blood through the systemic circuit to deliver ______ and nutrients.
The heart pumps blood through the systemic circuit to deliver ______ and nutrients.
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The pulmonary circuit exchanges O2 and ______ between the blood and the air in the alveoli.
The pulmonary circuit exchanges O2 and ______ between the blood and the air in the alveoli.
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The internal rhythm of the heart originates from the electrical signal generated by ______ cells.
The internal rhythm of the heart originates from the electrical signal generated by ______ cells.
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Sympathetic activation leads to an acceleration of the heart's ______.
Sympathetic activation leads to an acceleration of the heart's ______.
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Inhale leads to increased sympathetic activation, while exhale results in increased ______ impact.
Inhale leads to increased sympathetic activation, while exhale results in increased ______ impact.
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The contraction of the atrial muscles is caused by the electrical signal of the ______.
The contraction of the atrial muscles is caused by the electrical signal of the ______.
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The electrical signal is transmitted from the SA node to the ventricular muscle via the ______ fibres.
The electrical signal is transmitted from the SA node to the ventricular muscle via the ______ fibres.
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The contraction of the ventricular muscle starts after a delay of about ______ ms following atrial contraction.
The contraction of the ventricular muscle starts after a delay of about ______ ms following atrial contraction.
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Periodic changes of heart rate during deep inhalations and exhalations are known as ______.
Periodic changes of heart rate during deep inhalations and exhalations are known as ______.
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The sympathetic component can be estimated from the ______ period.
The sympathetic component can be estimated from the ______ period.
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To calculate heart rate variability (HRV), the use of ______ is recommended.
To calculate heart rate variability (HRV), the use of ______ is recommended.
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Following physical exercise, heart rate ______ gradually decreases to the resting value.
Following physical exercise, heart rate ______ gradually decreases to the resting value.
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Psychological factors can influence HR by ______ or decreasing it.
Psychological factors can influence HR by ______ or decreasing it.
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Vagal HRV is associated with various stress-related ______ and conditions.
Vagal HRV is associated with various stress-related ______ and conditions.
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Attentional capacity and cognitive control are positively associated with ______ HRV.
Attentional capacity and cognitive control are positively associated with ______ HRV.
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The perception of heartbeats is referred to as ______ accuracy.
The perception of heartbeats is referred to as ______ accuracy.
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Study Notes
Heart Activity and Electrocardiography (ECG)
- The heart's primary function is to pump blood, delivering oxygen and nutrients to tissues and removing waste products. This involves a systemic circuit and a pulmonary circuit for oxygen exchange.
- Heart contractions are rhythmic and directed by valves in the heart and blood vessels.
- The heart's intrinsic rhythm originates in the sinoatrial (SA) node, a pacemaker.
- Sympathetic and parasympathetic nervous system activity regulates heart rate and contractile force.
- Inhalation increases sympathetic activity, speeding up the heart rate, while exhalation increases parasympathetic activity and slows it down. This is called respiratory sinus arrhythmia (RSA).
- Oxygen and carbon dioxide levels in the blood can also affect heart activity.
ECG Signal Generation
- The ECG signal reflects the heart's electrical activity.
- Electrical signals originate in the SA node and spread through the heart.
- The atrial muscles contract in response to the SA node's electrical signals, the signal then moves through the atrioventricular node, bundle of His, and bundle branches, which depolarize the ventricles.
- The ECG measures the electrical activity as it goes through the heart, capturing the P wave (atrial depolarization), QRS complex (ventricular depolarization), and T wave (ventricular repolarization).
Pulse Plethysmography
- Near-infrared light is used to measure blood flow in capillaries using pulse plethysmography.
- Changes in blood volume in the capillaries are reflected in the amount of light transmitted.
- Portable devices (smart watches, bracelets) use this technique.
- Plethysmography provides continuous HR recording during daily activities.
Electrocardiogram (ECG) Measurement
- An ECG measures electrical activity, usually using 12 lead systems for diagnostic purposes.
- Electrodes placed on the skin pick up the electrical signals from the heart.
- Lead II is a common placement for electrodes on the body.
Heart Rate Variability (HRV)
- HRV assesses variations in heart rate between successive beats.
- HRV can reflect the balance between the sympathetic and parasympathetic nervous system.
- Measures like HF and RMSSD are sometimes used to evaluate impact of parasympathetic activity.
- HRV, the differences in the time intervals between the beats, can be recorded with appropriate sampling frequency to measure the heart rate.
Relationship between ECG and HR
- Heart rate (HR) is a measure of heart contractions per minute.
- HR is commonly measured with ECG.
- Other measures, like pre-ejection period (PeP,) which relates to the delay between heart beat and ejection of blood, allow for estimation of the sympathetic impact.
- An appropriate sampling rate is required to accurately calculate and analyze HRV. 30 Hz is sufficient for heart rate; higher sampling rates are preferred for HRV (300 Hz or higher).
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