Ion movement
This ion slowly leaks into SA Nodal Cells and initates the pacemaker potential ?
Sodium (Na+)
This ecg wave represents atrial depolarization
P Wave
The phase of the cardiac cycle when the ventricles contract is called
systole
The term that describes blood flow to body tissues
Perfusion
These vessels carry blood away from the heart under high pressure.
Arteries
Depolarization of autorhythmic cells is caused primarily by the influx of this ion?
Calcium (Ca2+)
The qrs complex represents this electrial event
Ventricular depolarization
The amount of blood ejected by one ventricle during a single contraction
Stroke volume
This feature of cardiac muscle prevents tetany
long refactory period
Which type of vessel is the primary site of gas nutrients and waste exchange?
Capillaries
Repolarization of cardiac cells occurs when this ion leaves the cell
Potassium (K+)
Atrial repolarization is not visible on an ecg because it is masked by this event
Ventricular depolarization
Cardiac output is calculated using heart rate and this variable
stroke volume
CO= HR x SV
Why must the heart relax between contractions
To allow for ventricular filling
Compared to arteries, veins contain this structural feature to help move blood back to the heart
Valves
If potassium channels in cardiac cells opened earlier than normal, how would this most directly affect the action potential and the heart’s ability to contract?
Repolarization would occur sooner, shortening the action potential and weakening contraction
A prolonged PR interval on an ECG suggests a problem at this structure
AV node - 3 degrees of blockage with varying severity
An increase in heart rate with no change in stroke volume will cause cardiac output to _____
Increase
Why does increased parasympathetic stimulation decrease cardiac output?
It lowers heart rate
Blood pressure drops the most dramatically when blood flows through these vessels
Arterioles have the most significant drop, and capillaries have the lowest blood pressure to allow for nutrient exchange to prevent rupture since they only have single-cell-thick layers.
If the potassium channels failed to open properly, what phase of the action potential would be most affected?
Repolarization
On an ECG, what does the ST segment represent in the phases of cardiac muscle action potential, and why is this phase important for heart function?
The plateau phase; it is important because it prolongs contraction and prevents tetany, allowing for coordinated ventricular pumping
During ventricular systole, some blood remains. What is this blood called and why is it important for the next cardiac cycle
End systolic volume (ESV) it contribute to ventricular filling and helps maintain cosistent stroke volume in the next cycle
Autonomic regulation of heart rate works primarily by altering this at the cellular level
Ion channel activity (K+ out, Na+ In and Ca2+ in)
Why does increased venous pressure often lead to edema
Increased hydrostatic pressure forces fluid out of capillaries into surrounding tissues.