Lab 13 Flashcards
Is located in the medulla oblongata where it receives input from various sensory receptors (proprioceptors, baroreceptors, chemoreceptors) and higher brain centers (cerebral cortex, limbic system).
Cardiovascular center
Output from the cardiovascular center is via ________ and __________ neurons of the autonomic nervous system.
Sympathetic; parasympathetic
Cardiac excitation normally begins at the __________ node (dominant pacemaker of the heart) which lies in a cellular cluster in the right atrial wall between the inlets of the inferior and superior vena cava
Sinoatrial (SA)
Located within the lower interatrial septum, relays the impulse from the atria to the ventricles.
Atrioventricular (AV) node
After the impulse passes through the AV node, it enters the fiber tract known as the AV bundle or
Bundle of His
This short pathway subdivides into ______ and _____ bundle branches. The bundle branches extend through the interventricular septum toward the apex of the heart
Right; left
The smallest conductive elements, the _______ _______, are distributed throughout the inner walls of the ventricles, throughout the muscular septum separating the two ventricles, and within the muscular papillae where they make intimate contact with contractile elements of the heart.
Purkinje fibers
The measurement and analysis of currents associated with heart activity, is extremely important in the diagnosis of abnormal cardiac function.
Electrocardiography
The recording of the electrical changes
Of the heart is called an:
Electrocardiogram (ECG or EKG).
The heart is seen as a dipole, i.e. a pair of point sources of electrical charge equal in magnitude but opposite in sign. Current flows between the two poles throughout the volume conductor. The particular arrangement of the two electrodes is known as a:
Lead
The normal electrocardiogram is composed of a:
P wave, a QRS complex and a T wave
The upward (positive) deflection associated with atrial depolarization. The average duration is 0.08 second (range 0.06 - 0. 12 sec) and the amplitude (height) is not greater than 0.3 millivolts.
P wave
Series of negative and positive deflections associated with ventricular depolarization, It is measured as the portion of the tracing from the beginning of the Q wave to the end of repolarization of the atria takes place simultaneously and is obscured by the ventricular
changes. The average duration is 0.08 second (range 0.06 - 0.10 sec) and the amplitude of the R wave is not over 2.5 millivolts.
QRS complex
The positive deflection following the QRS complex representing ventricular repolarization.
T wave
The T wave is of longer duration and lower amplitude than the initial depolarization (QRS complex), which suggests that the ventricular repolarization is ______ and less well synchronized.
Slower
An _______ (negative) T wave is considered to be abnormal.
Inverted
The average duration of the T wave is about 0.16 second; the amplitude is about 0.3 millivolts but is:
Highly variable
a-b atrial _________
Contraction
b-c atrial _________
Relaxation
c-d ventricular _________
Contraction
d-e ventricular _________
Relaxation
The term ______ refers to the alternating surges of pressure (expansion and then recoil) in an artery
that occur with each contraction and relaxation of the left ventricle.
Pulse
Normally the pulse rate (pressure surges per minute) equals the heart rate (beats per minute) and the pulse averages _______ beats per min
70 - 76
This pressure varies with the cardiac cycle, whether the heart muscle is in _______ (contracted state) or in _______ (relaxed state).
Systole; diastole
You will use an instrument called a sphygmomanometer to measure _______ blood pressure.
Arterial
Systolic pressure can be defined as the
maximum pressure in the arteries during ventricular __________ (systole).
Contraction