Week 5, Lecture 1 Flashcards
which ventricle pumps more blood per minute
left ventricle
The left ventricle pumps more blood per minute than the right ventricle. Although both ventricles pump the same volume of blood over time, the left ventricle is responsible for pumping oxygenated blood to the entire body, which requires a greater force and pressure. In contrast, the right ventricle pumps deoxygenated blood to the lungs, which is a shorter distance and requires less pressure. So, while their output is equal in volume, the left ventricle works harder overall due to the demands of systemic circulation.
what is the flow of blood through the heart
deoxygenated from vena cava –> RA –> tricuspid valve –> RV –> pulmonary valve –> pulmonary circulation (blood to lungs to get oxygen)
oxygenated blood returns through pulmonary veins –> left atrium –> mitral valve –> left ventricle –> aortic valve –> aorta (oxygenated blood to the body)
Deoxygenated Blood Entry: Blood that is low in oxygen returns to the heart from the body through two large veins: the superior vena cava (from the upper body) and the inferior vena cava (from the lower body).
Right Atrium: The deoxygenated blood enters the right atrium, a chamber at the top right side of the heart.
Tricuspid Valve: When the right atrium contracts, blood flows through the tricuspid valve into the right ventricle.
Right Ventricle: The right ventricle pumps the deoxygenated blood through the pulmonary valve into the pulmonary arteries.
Pulmonary Circulation: The pulmonary arteries carry the blood to the lungs, where it picks up oxygen and releases carbon dioxide.
Oxygenated Blood Return: The now oxygen-rich blood returns to the heart through the pulmonary veins.
Left Atrium: The oxygenated blood enters the left atrium.
Mitral Valve: The left atrium contracts, pushing blood through the mitral valve into the left ventricle.
Left Ventricle: The left ventricle, which has the thickest walls to generate high pressure, pumps the oxygenated blood through the aortic valve into the aorta.
Systemic Circulation: The aorta distributes the oxygen-rich blood to the rest of the body.
what are the 2 things that force a cardiomyocyte generates with each systole depends on
- PRELOAD
overlap between actin and myosin during diastole - INOTROPY
amount of calcium available to bind troponin
what is inotropy
AKA contractility
Amount of calcium available to bind to troponin
factors that increase inotropy
HR, SNS, cortisol, TSH
▪ Increased sympathetic nervous system
stimulation
▪ Increased heart rate (“loads” more calcium in the SR during relaxation)
▪ Things that increase SNS effectiveness – thyroid hormone, cortisol, etc.
what is preload
ventricular filling
Preload is the filling pressure of the heart at the end of diastole.
preload vs afterload
Preload is the initial stretching of the cardiac myocytes (muscle cells) prior to contraction. It is related to ventricular filling. Afterload is the force or load against which the heart has to contract to eject the blood.
positive ionotriopic agents (i.e. increase contractility)
certain hormones (e.g., epinephrine) and drugs (e.g., digitalis), can increase the force of contraction, leading to increased sarcomere shortening.
what do positive ionotropic agents do to sarcomere length
increase sarcomere shortening because of increases contraction force
negative ionotropic agents
reduce the force of contraction, which can be associated with reduced sarcomere shortening.
what increases force development
good overlap of actin and myosin
right atrium pressure tracing
A, C, X, V, Y waves
- A Wave – Atrial contraction (atrial systole)
- C Wave – Bulging of tricuspid
- X Wave – Atrial relaxation (atrial diastole)
- V Wave – Passive filling of the atria (ventricular systole)
- Y Wave – Emptying of atria into the ventricles with the opening of AV valves (early diastole).
isovulmetric
there is a change in pressure, but no change in volume
are the valves open or closed if isovolumetric
closed
systole vs diastole
- Systole – when the chamber applies pressure work to blood through contraction
- Diastole – when the chamber no longer applies pressure work to blood through contraction
wiggers diagram good to show that
- The Wiggers diagram is a good way to illustrate that the ventricle cannot:
▪ eject blood into the great artery until its pressure is greater than that in the artery
▪ accept blood from the atria unless its pressure is less than that in the atria - Valves ensure that blood only flows one direction despite the large changes in ventricular pressure
rapid ventricular slowing vs. slower filling
what is rapid ventricular filling because of?
what is rapid ventricular filling aka?
- Rapid ventricular filling is due to the rapid expansion of the ventricle and the drop in volume that ensues
▪ Also known as passive filling, and it is responsible for 80% of ventricular filling at rest
▪ Passive filling takes time – decreased with increased heart rates
what does aorta pressure oscillate between>
around 80-120
Aortic pressure oscillates between systolic and diastolic pressure
what happens when the aortic valve closes? what’s the notch called in between?
- After the aortic valve closes, a secondary wave can be seen
▪ The division between these two waves is known as the dicrotic notch
2 waves with dicrotic notch in between
what is the most accurate marker or aortic valve closeure
dicrotic notch
what is the 2nd wave from in aortic pressure curve
▪ The secondary wave is thought to be formed by the elastic recoil of the aorta against a closed aortic valve
▪ Likely also partially impacted by complex vibrations due to the “weird” shape of the aorta
S3 and S4 sounds in phonocardiogram- are they healthy?
s3 can be heathy, s4 bad
- S3–oftenfoundinhealthy young adults and children
▪ New emergence is usually pathological in adults (often indicator of myocardial ischemia)
▪ Blood enters a non- compliant or “not-fully- relaxed” ventricle during rapid filling - “Kentucky”(eeisS3)
- S4 – usually pathologic
▪ Ventricle “straining” as the atria contract and “force” blood into a non-compliant ventricle - “Tennessee”(TennisS4)
how does right and left heart differ
right heart has lower ventricle pressure and pulmonary artery pressure is way less than aorta on left side
atrium is relatively similar
- Note the lower pressures that develop in the right ventricle and pulmonary arteries
- Pulmonary artery pressure is ~ 25/7 mm Hg
- Slightly lower atrial pressures in the right vs. left