ANATOMY
TRUE OR FALSE: The Right Ventricle tends to be smaller than the Left Ventricle, for it generally takes less muscle to pump its blood from the heart through the pulmonary trunk into the L&R pulmonary arteries and into the lungs
TRUE: blood being pumped from the Right Ventricle to the lungs encounters approximately FIVE TIMES LESS FRICTION/PRESSURE than that encountered by blood exiting from the Left Ventricle into the Aorta
the RIGHT ATRIUM
The AV valve connecting the Right Atrium and Right Ventricle is given this name, because it has THREE flexible flaps called "cusps"
"TRICUSPID" VALVE (a.k.a. Right AV valve)
This is the name for the site of a cell mass in the right atrial wall, just inferior to the entrance of the superior vena cava, where typical cardiac pacemaker cells are found that normally generate impulses about 75 times per minute, setting the pace for the heart as a whole (because no other region of the conduction system of the myocardium has a faster depolarization rate)
the SINOATRIAL NODE (aka SA node)
This is the three-letter abbreviation for a monitored reading of the composite sum of all electrical currents (APs) generated by nodal / cardiac contractile cells
at a given time
EKG (or ECG)
NOTE: both mean "Electrokardiogram," it just depends on whether one uses the traditional form based on the original GERMAN adjectival term for heart "kardio-" or instead adapts it to the English spelling "cardio-"
The heart is enclosed in a double-walled sac that is called THIS
(bonus points: beyond the general name, also name its specific LAYERS)
General Answer: PERICARDIUM
Bonus points: its superficial layer: loosely-fitting FIBROUS PERICARDIUM made of dense CT;
deep to the fibrous pericardium is the two-layered SEROUS PERICARDIUM composed of the outer PARIETAL layer and the inner VISCERAL layer (visceral layer is also called the "EPICARDIUM")
TRUE OR FALSE: Although the pressure at the outset of the Pulmonary Circuit (around 24/8 mmHg) is much lower than the pressure at the outset of the Systemic Circuit (typically 120/80 mmHg or less in a healthy adult), EQUAL VOLUMES of blood are pumped to and through each of these two circuits at any given time
TRUE
This is the general name given to BOTH the valves through which blood exits out of the heart, likely because the valves each have three "cusps" that individually are roughly in the shape of a crescent moon. Bonus points: also give the specific name of each of these two valves
SEMI-LUNAR (SL) VALVES:
the Pulmonary Valve (exiting from Right Ventricle toward Lungs) and the Aortic Valve (exiting from Left Ventricle toward systemic and coronary circulation)
From the SA node, the depolarization wave spreads via gap junctions through the atria and also to the inferior portion of the interatrial wall/septum immediately above the tricuspid valve to a collection of pacemaker cells called THIS, where the electrical impulse is delayed for about 0.1 sec
the ATRIOVENTRICULAR node (aka AV node),
whose name tells you that it lies between the atria and the the ventricles!
This is the deflection wave on an EKG that is usually tall and spiky, representing ventricular depolarization, marking the firing of the AV node (just before ventricular systole)
QRS WAVE
This is the name for the most inferior "tip" of the heart that comes into contact with the chest wall anteriorly, and that points generally downward in the direction of the left hip. When listening to ("auscultating") the heart through a stethoscope, this is the place where it can often be heard the best
the APEX
After returning to the heart via four separate pulmonary veins, name the first three structures, in order, that oxygenated blood enters next
LEFT ATRIUM, passing through the Mitral valve to the LEFT VENTRICLE, passing through the aortic valve into the AORTA
The left atrioventricular (AV) valve, controlling blood flow between the left atrium and the left ventricle, is commonly called by TWO DIFFERENT NAMES. Give these two names
BICUSPID or MITRAL valve (the "mitre" being the pointed hat worn by Catholic Popes, which some early European anatomist must have thought the shape of this valve resembled)
This is the name given to the subendocardial conducting network of barrel-shaped cells with few myofibrils that completes the electrical pathway through the interventricular septum, penetrates the heart apex, and then carries out the bulk of the depolarization of the rest of the ventricles
PERKINJE FIBERS
This deflection wave on an EKG comes just before the tall spiky QRS wave and represents atrial depolarization, the time it takes the depolarization wave to travel from the SA node down through the atria and to the AV node
P WAVE
Cardiac muscle cells/fibers (called "myocardium") are tethered by criss-crossing CT fibers that form a dense "fibrous skeleton" around the heart. LIST TWO FUNCTIONS of this anatomical structure
(1) REINFORCES THE MYOCARDIUM INTERNALLY
(2) ANCHORS CARDIAC MUSCLE FIBERS
(3) LIMITS THE DIRECT SPREAD OF ACTION POTENTIALS ACROSS THE HEART except via specific pathways (since CT is not electrically excitable)
Name the THREE different circuits that circulate blood from the heart to different parts of the body.
(1) PULMONARY CIRCUIT: blood to/from lungs;
(2) CORONARY CIRCUIT: supplies blood for the physical needs of the heart organ itself;
(3) SYSTEMIC CIRCUIT: blood to rest of the body
When the heart ventricles contract at the start of systole, blood gets compressed in the ventricles raising intraventricular pressure, forcing blood superiorly against the AV valve flaps, causing them to close. NAME THE CHORD-LIKE STRUCTURES attached to these valves inferiorly to keep them anchored in the closed position so that they do not blow upward into the atria
CHORDAE TENDINAE (helped by the "papillary muscles" that help "take up the slack" in them)
The ATRIOVENTRICULAR (AV) bundle, aka the "Bundle of HIS"
note: "His" comes from the last name of a Swiss cardiologist, Wilhelm His, Jr.
This short segment of the EKG, coming AFTER the tall spiky QRS wave, represents ventricular contraction, corresponding to the plateau of the myocardial AP. During this phase the entire ventricular myocardium is depolarized
S-T segment
In most healthy children and adults one finds in the Interatrial Septum (the wall between the two atria) a small depression called the "fossa ovalis" which is the remains of a previous fetal structure. NAME that fetal structure, and for bonus points explain what its purpose was.
FORAMEN OVALE, an opening connecting the right and left atria while the fetus is in utero. Since fetal lungs are not yet developed and not yet ready to oxygenate blood, there would be no purpose to pump blood from the right ventricle into the lungs of the fetus, so instead blood shunts directly from the right atrium into the left atrium. Oxygenation of fetal blood takes place instead in the placenta. Shortly after birth when the neonate takes their first breaths, this opening should normally close for good.
ANGINA PECTORIS (in this condition myocardial cells are weakened but they do not die, unlike what happens with more prolonged blockage that leads to Myocardial Infarction --M.I., aka Heart Attack-- in which myocardial cells do die)
Explain how the heart sounds heard when auscultating the heart (the "lub-dup" sounds) correspond to events taking place in the heart
The first sound ("lub") occurs as the AV (tricuspid and mitral) valves close, signifying the point when ventricular pressure rises above atrial pressure (the beginning of ventricular systole). The second sound ("dub") occurs as the SL (pulmonary and aortic) valves snap shut at the beginning of ventricular relaxation (diastole).
If the faster pacemakers of the heart stop functioning, that is, if the SA node (about 75 bpm) and the AV node (about 50 bpm) are knocked out for some reason such as a "Heart Block," the conducting network of the heart would still fire off slower signals from atypical pacemakers (e.g. AV bundle and Purkinje fibers) at approximately THIS MANY beats per minute
30 bpm
Note that this rate can keep the body alive for a short time, but is too slow to maintain adequate circulation throughout the body
Explain briefly why on a normal EKG one never sees any sign or effect of atrial repolarization
Atrial repolarization is OBSCURED BY THE QRS WAVE (since the electrical activity of ventricular depolarization is so much greater and more significant than atrial repolarization, on the scale displayed on an EKG)