A&P II lab Flashcards
Occurs during relaxation of the ventricles (diastole) and is made by the closure of the semilunar valves. The dupp of “lubb-dupp”
Second heart sound
Made by the turbulence of the blood as it fills the ventricles during atrial and ventricular diastole (passive filling) following the opening of the atrioventricular valves.
Third heart sound
Made by the turbulence of the blood as it moves from the atria into the ventricles during atria systole (active filling). This occurs right before the ventricles begin to contract and force the atrioventricular valves closed.
Fourth heart sound
Zero line or baseline
Isoelectric line
Depolarization of the atria; 0.07-0.18s
P wave
Extends from the start of the P wave to the start of the QRS complex; depolarization wave travels from SA node to the ventricles; 0.12-0.20s
PR interval
Extends from the end of the P wave to the start of the QRS complex; time between depolarization of the atria and depolarization of the ventricles; 0.02-0.10s
PR segment
Depolarization of the ventricles and repolarization of the atria
QRS complex
Onset of ventricular depolarization to the end of ventricular repolarization; refractory period of the ventricles
QT interval
Extends from the end of the S wave and the start of the T wave; ventricles are uniformly depolarized
ST segment
Repolarization of the ventricles
T wave
Repolarization of the ventricles to atrial depolarization
TP segment
Occurs during contraction of the ventricles (systole) and is made by closure of the atrioventricular valves and the opening of the semilunar valves. The lubb part of lubb-dupp
First heart sound
In “standard” electrocardiography, cardiac electrical activity is recorded from three perspectives, leads I, II, and III, Why are all 3 perspectives necessary? In other words, what’s the advantage of recording and analyzing all, as opposed to just one?
The heart is a 3 dimensional structure and its electrical activity is also in 3 dimensions. Each lead looks at the heart from a different perspective determined by the placement of the leads electrodes. Thus each lead is sensitive to a particular region of the heart in expense of the others.
The “typical” mean QRS axis for humans is about +59 degrees. How far from +59 degrees can the axis deviate and still be considered within normal limits? What are some causes fro pathologically significant left and right mean QRS axis deviations?
The normal range is between -30 and +90 degrees. Normal deviation can be due to body position, height, weight, and fitness level. Significant abnormal deviations to the left can occur if the left ventricle become hypertrophied. This is a common occurrence in peripheral vascular resistance. A significant right deviation that is pathological can be caused by the opposite. Not common
What would happen to the ECG trace if the subject sneezed or laughed during the recording? Why?
Just before sneezing, most people take a deep breath. This increases pressure in the chest and briefly inhibits the flow of blood to the heart, which can lower blood pressure and increase the heart rate. But as you exhale, you blood pressure increases and heart rate, in turn, goes down. At the same time, sneezing stimulate the vagus nerve, which runs from the brain through the abdomen.
If ventricular myocyte (cardiac muscle cell) is in mid to late plateau phase, what segment of the ECG are we in? What is happening in the ventricle at this time?
During the plateau phase of the action potential the EKG line will be flat (isoelectric line) because the ventricles are completely depolarized. This is also the point at which the ventricles experience isovolumetric contraction-the pressure has not built up enough to open the semilunar valves and thus no blood is being ejected yet. On the EKG this flat line would correspond to the ST segment
- Predict what would happen to your subject’s BP if they began to run in place.
During exercise the sympathetic NS will increase cardiac output (amount of blood pumped/minute) and increase vasoconstriction. The overall result will be an increase in BP. During light exercise this may not be noticeable, or may only be in the systolic BP measurement.
- What specifically is meant by the term auscultation and how is it used to deduce systolic and diastolic pressures?
Auscultation describes the technique by which internal bodily sounds are detected using a stethoscope. This can be used to deduce BP with the help of a blood pressure cuff. The cuff is wrapped around the arm and the pressure is increased until blood flow through the brachial artery is shut off. The cuff pressure is then slowly released. At the point when blood begins to spurt through the vessel below the cuff a sound is detected using the stethoscope. This indicates the pressure during contraction (systolic BP). As the pressure continues to decline, eventually the sound will go away; this indicates that blood flow is again laminar. This represents the diastolic BP, or pressure when the heart is at rest.
3.What changes in the finger pulse would you have expected to find?
The finger pulse transducer would detect arterial pressure only when the brachial artery was not compressed. Thus, it would read a pulse prior to the cuff being tightened, and again after the cuff pressure was released enough to allow blood to flow.
- What is the difference btwn the sounds heard when taking BP and the sounds heard in the heart during the cardiac cycle? what causes these sounds?
Korotkoff sounds are heard as blood flows through the brachial artery, but only after flow has been shut off briefly by the cuff and is caused by turbulence. The first 2 heart sounds are heard when the AV valves close (S1) and semilunar valves close (S2) respectively.
- What can cause a “heart murmur?” Can a heart murmur be detected using a stethoscope? How about by examining an EKG?
Murmurs are caused by faulty valves, stenotic valves or septal defects. These are easy to detect using auscultation. ECG recordings will not directly indicate a murmer from a valve or septal defect. However, an ECG is typically not done without the physician having first listened to the heart.
flow that is silent
laminar
flow that is noisy
turbulent
peak arterial pressure (normal 100-139 mmHg)
systolic pressure
arterial pressure during ventricular diastole (normal 60-89mmHg)
diastolic pressure
