TBL 11: Cardiac Cycle Flashcards
Visually recall the route of blood circulation to and from the heart.
How is the murmur from a prolapsed mitral valve classified?
Which heart chamber is affected and why can pulmonary edema result?
Define systole and diastole.
What is the normal heart rate (pulse)?
systole - contraction
diastole - relaxation
normal adult heart rate - 60-100 beats/minute
Describe the events associated with diastole.
Diastole begins after closure of the aortic and pulmonary valves, and after opening of the mitral and tricuspid valves.
During diastole, the SVC/IVC and pulmonary veins refill the atria and begin ventricular refilling without retrograde (reverse) flow into the ventricles from the aorta or pulmonary arteries.
At the end of diastole, atrial compression completes ventricular refilling (“compression” because atrial contraction is relatively mild to ventricular contraction)
Describe the events associated with systole.
Systole begins with closure of the mitral and tricuspid valves
During systole, ventricular contraction thrusts open the aortic and pulmonary valves propelling blood into the aorta and pulmonary arteries without retrograde flow into the atria.
Also during systole, increased vascular pressure initiates the return of venous blood into the atria.
What are the normal systolic/diastolic pressures in the systemic and pulmonary arteries, respectively?
normal systemic arterial pressure - 120/80
normal pulmonary arterial pressure - 20/8
What is the oxygen saturation in:
- a) right atrium, right ventricle, and pulmonary arteries?*
- b) left atrium, left ventricle, and aorta?*
oxygen saturation:
- a) right atrium, right ventricle, pulmonary arteries* - 75%
- b) left atrium, left ventricle, aorta* - 95%
What can be found surrounding the atrioventricular orifices and the orifices of the aorta and pulmonary trunk?
surrounding the atrioventricular orifices and the orifices of the aorta and pulmonary trunk there are rings of dense connective tissue that reinforce the valves and insure their proper opening and closing during the cardiac cycle.
How many cusps do the following valves contain:
aortic, pulmonary, mitral and tricuspid valves
amount of cusps:
THREE CUSPS: aortic, pulmonary, and tricuspid
TWO CUSPS: mitral (aka bicuspid)
What creates the heart sound S1?
What creates the heart sound S2?
heart sound S1: systolic closing of mitral (bicuspid) and tricuspid valves
heart sound S2: diastolic closing of aortic and pulmonary valves
Where are the auscultation sites for the aortic and pulmonary valves?
Where are the auscultation sites for the bicuspid and tricuspid valves?
Auscultation sites:
- aortic/pulmonary valves* - parasternal lines in the right and left 2nd ICS
- bicuspid/tricuspid valves* - parasternal & midclavicular lines in the left 4th and 5th ICS
What are the two most common valvular abnormalities? Describe them both.
How are these abnormalities typically identified?
Aortic valve stenosis
- stenosis (narrowing) is the failure of a valve to fully open, thus slowing the forward flow of blood.
Mitral valve prolapse (insufficiency)
- valve prolapse (insufficiency) is the failure of a valve to fully close thus allowing reverse blood flow into a chamber.
Both of these abnormalities create turbulent blood flow that create eddies (small whirlpools) that produce audible vibrations called murmurs and tangible superficial vibrations called thrills than can be felt on the skin over an area of turbulence. A specific abnormality can be ascertained by identifying a murmur and analyzing its temporal relation to the cardiac cycle. So murmurs are often described as a systolic, diastolic, or continuous murmur.
What else can also be responsible for heart murmurs besides a stenotic or prolapsed valve?
Any structural deformity of the heart such as:
- abnormal cardiac chambers
- septal defects between chambers
- anomalies of the great vessels
Why are ausculation sites situated superficial to the chamber or vessel into which blood has passed rather than directly above the valves?
Blood tends to carry an abnormal sound in direction of its flow therefore the typical ausculation sites are situated superficial to the chamber or vessel into which the blood has passed and in a direct line with the valve orifice.
How is the murmur from a prolapsed mitral valve classified?
Which heart chamber is affected and why can pulmonary edema result?
A prolapsed mitral valve results in blood regurgitating into the left atrium when the left ventricle contracts. The backward flow of blood could increase the pressure in the left atrium which can obstruct the normal amount of blood it receives from the pulmonary vein, leading to pulmonary edema.
Why does left ventricular hypertrophy with associated dyspnea result from aortic valve stenosis?
How is the resulting murmur classified?
In an aortic valve stenosis, the left ventricle has to work harder to get blood pumped into the systemic circulation, resulting in left ventricle hypertrophy. Also since the systemic circulation is getting reduced blood flow, this means the body is not getting sufficient access to oxygenated blood resulting in feelings of inadequate oxygen supply (dypsnea).
The murmur is systolic.
Identify structures labeled A through D in the image below.
What is unique about structure D?
Structure D (apex of heart) is also the auscultation site for the mitral (bicuspid) valve.
Identify structures labeled A through C in the image below.
What are auricles, where can they be found, and what do they do?
Auricles are two pouch-like projections from the atria of the heart that increase atria capacity.
The right auricle overlaps the ascending aorta and the left auricle overlaps the pulmonary trunk.
Identify structures A through E in the radiograph below.
What can affect the size of structure B?
Structure B (arch of aorta aka “aortic knob”) often increases in size when there is an increase in blood flow or it can decrease in size when there is a decrease in blood flow.
Identify structures A through D in the image below.
What is the main vein of the heart, and where does it empty into?
The coronary sinus is the main vein of the heart, and it empties into the right atrium along with the IVC and SVC.
Which portion of the interior wall of the right ventricle is smooth, which is rigid, what makes it rigid and why?
the outflow portion of the interior wall of the right ventricle is smooth
the inflow portion is rigided by cardiac muscle
Identify structures A through E in the image below.
Also, define the function of structure C.
Stucture C (fibrous chordae tendineae) are responsible for connecting the free ends of the three cusps of the tricuspid valve to the papillary muscles (structures E & F).
They act as cords attaching to a parachute and during systole, papillary muscle contraction tenses the cords to insure tight closure of the cusps thereby preventing retrograde flow in to the right atrium.
What is the major difference between the left atrium and the right atrium?
What is the major difference between the left ventricle and the right ventricle?
The interior wall of the left atrium is completely smooth while the anterior aspect of the interior wall of the right atrium has a rigid portion full of cardiac muscle.
The left ventriclular wall is nearly double the thickness of the right ventricular wall due to the drastic increase in systemic pressure compared to pulmonary pressure.
What structure can be found immediately posterior to the left atrium (starred region in the image below)
THE ESOPHAGUS!
Where can ridged cardiac muscle be found within the left ventricle? What added function does this cardiac muscle have besides contraction?
Rigid cardiac muscle can be found all over the interior wall of the left ventricle except for near the smooth outflow portion.
This muscle also prevents suction that would otherwise occur with a flat surface and would impair pumping efficiency.
Of the four valves of the heart, which lack chordae tendineae?
Explain when and how the remaining valves close?
The pulmonary and aortic valves lack chordae tendineae so they are reliant on pressure gradients to open and close.
The mitral and tricuspid valves possess chordae tendineae that are attached to papillary muscles which contract during systole to tightly close these valves, ensuring that there is no retrograde flow of blood during the chamber’s contraction.
