Cardiovascular Flashcards
(192 cards)
How are the AV valves attached to the heart?
Chordae tendinea attach valves to the papillary muscle
How do semilunar valves close?
Pressure gradient caused by blood being pushed back following contraction
Describe the steps of the cardiac cycle?
Atrial Systole begins
Atrial Systole ends, atrial diastole begins
Ventricular systole first phase (AV valves pushed closed by ventricular contraction- contraction not strong enough to open semilunar though)
(Isovolumetric contraction)
Ventricular systole second phase (pressure of ventricle exceeds arteries, causing semilunar valves open -> blood ejected)
Ventricular diastole early (Ventricles begin to relax, ventricular pressure drops, semilunar valves close due to backflow)
(Isovolumetric relaxation)
Ventricular diastole late (all chambers relaxed, ventricles fill passively)
When does isovolumetric relaxation and contraction occur?
Contraction- between atrial systole ending/ diastole beginning and ventricular systole first phase starting
Relaxation- at the start of ventricular diastole
When do the valves open and close?
Semilunars open- when ventricular pressure exceeds aortic pressure
Semilunars close- when aortic pressure exceeds ventricular pressure
AV valves open- when ventricular pressure has dropped and is equivalent to atrial pressure
AV valves close- when ventricles begin contraction
What is inotropy and how does positive/negative inotropy impact stroke volume?
Contractile capability of the heart itself- how contractile the cells are
Positive- greater response of contraction (would increase stroke volume)
What is the equation for cardiac output?
Stroke volume x Heart Rate
What is the equation for blood pressure?
Cardiac Output x Peripheral Vascular Resistance
What do cardiac contractile units look like?
Arranged linearly using intercalated discs
Contain a lot of mitochondria
Arranged in parallel with each other to enhance contraction efficiency
What is the resting membrane potential of cardiac myocyte cells?
Around -80mV
What is the general concentration of K, Ca and Na in cardiac cells?
High K intracellular concentration
Low intracellular Ca and Na
What is the plateau phase and what causes it
Equal flow of ions in and out of cardiac cells
What are the steps of cellular action potential of triggering contraction of cardiac myocyte cells?
Phase 0- Opening of voltage gated Na channels allowing for inward Na current. Rapid depolarization Phase 1 (notch)- Activation of outward K causing initial repolarization Phase 2 (plateau)- Balance of inward Ca and outward K flow- Plateau phase Phase 3- Repolarization phase, outward K predominates Phase 4- Resting action potential
Do SA node cells ever reach resting membrane potential?
No, always active
Similar in AV node
What is the back-up mechanism set up by the cells in the heart?
SA Node has constant slow depolarization with spontaneous depolarization.
AV node has this too but it is spontaneously active at a lower rate (intrinsically active in case something happens to the SA node)
Pirkinjes do this too
How does calcium levels relate to action potential and contraction of the heart?
Action Potential depolarization causes increase in intracellular calcium transient, this allows for calcium binding to troponin, and binding of myosin to actin causing contraction
Describe the movement of Calcium during the Ca induced Ca release.
L type calcium channels open (due to depolarization), allowing more calcium influx from T-tubule.
Ca reaches sarcoplasmic reticulum. Ryanodine Receptor on SR sense incoming of calcium through L-type calcium channel following action potential, and will then allow calcium release from SR.
What is the L-type calcium channel?
Voltage gated calcium channel that allows inward flow of calcium once action potential initiates its opening
What causes relaxation of cardiac cells (related to calcium) following contraction?
Pump on SR pumps calcium into SR to store
Calcium exchanger moves calcium out of cells
Lack of intracellular calcium causes blocking of actin from myosin via troponin re-binding
What exchanger(s) moves calcium out of cardiac cells?
Ca-Na exchanger: Moves 3 Na into cell in exchange for 1 Ca out
ATP pumps: Used to move Ca out.
K-Na Pump: used to exchange 3 intracellular Na out, for 2 K, helping to control ion levels
Where do the coronary arteries stem from?
Aortic sinus
When does coronary flow occur?
During ventricular diastole
Aortic Valve shuts, pressure in ventricle falls, there is now a pressure gradient- higher pressure in aorta, and lower in ventricular muscle allowing for coronary flow (blood will flow backwards in aorta due to the higher aortic pressure and blood will flow down to coronary arteries)
What structure makes up the inferior, superior, right, and left border of the heart?
Inferior-Right ventricle
Right- right atrium
Left- Left ventricular wall
Superior- great vessels, part of left and right atrium
What is occurring within the heart between the lub-dub?
Ventricular systole is beginning and ending during this period
Ventricular pressure is high, aortic pressure is high