Heart Activity and Behaviour Flashcards
Purely off its own accord, the SA node would set our heart rate at around ______, but vagus input sets it down more to ______.
120bpm
70-80
The oft-cited normal resting heart rate is….
…. 72bpm.
positive chronotropy is a fancy term for
increased heart rate.
Principal CNS control comes from the _____.
Medulla.
What other structures have been implicated in CNS HR control?
hypothalamus, amygdala, cerebellum
Where do we find the baroreceptors in that eponymous reflex?
The CAROTID SINUS; responsible for the carotid sinus reflex.
What’s the main point of the carotid sinus reflex?
Making sure the brain gets enough blood.
Where do we find the cardiac acceleration centre?
The medulla.
Low pressure in the carotid sinus activates the nerve signals to where? Leading to what?
Cardiac acceleration centre of the medulla; results in sympathetic drive (increased HR and BP).
What valves are closing in the LUB sound? What’s this representing?
The closure of the atrioventricular valves in ventricular systole.
Just remember their in a lub-triangle (TRIcuspid valve closing the LUB sound).
What is the P wave? What’s going on the the heart?
Represents propagation of SA signal.
In a ms time, atrial systole will take place.
Which wave landmark represents ventricular depolarisation?
QRS complex.
Which wave represents atrial repolarisation?
Trick question it doesn’t have one - it’s hiding behind the QRS complex.
When in the ECG is ventricular contraction occurring?
Lumbers after the QRS complex (i.e. during but not neatly aligned with the ST interval).
When does ventricular diastole occur in the ECG?
Immediately following the T wave.
The PQ interval is around _____s
0.16s
The QT interval is around _____s
0.30s
The cardiac cycle is around ______s
0.83s
Of the only ca. 800ms of the cardiac cycle, __________ takes up the majority, with about __________.
Diastole; 500ms.
The heart spends more time relaxing than contracting.
What cardiac landmark do monitoring systems use to calculate HR?
R wave
“Rate” wave. Also like it’s the biggest one so makes sense.
What are five things that impedance cardiography can measure?
Stroke Volume Cardiac Output Ventricular Ejection Volume Myocardial Contractility Total Peripheral Resistance
What nerve sense messages from the carotid sinus to the medulla?
The glossopharyngeal nerve (IX)
HR might have an interesting relation to reaction time. What are three points that support this?
- Fixed foreperiods gave HR deceleration.
- Random foreperiods gave NO HR deceleration.
- Magnitude of the effect dependent on cardiac cycle stage.
HR could have an interesting relationship with motor performance. What are two points that are worth looking into?
- HR during a motor performance activity exceeds metabolic demand; the emotional aspect probably makes the discrepancy (metabolic demand doesn’t account).
- Studies in drivers shows that HR decreases as someone improves at a motor skill.
