integration of cardiac function Flashcards
(50 cards)
explain why blood pressure only increases slightly during exercise when the cardiac output is greatly increased
because although the venoconstriction causes increased pressure, it is counteracted by the arterial vasodilation in the skeletal muscle which decreases the TPR
what does sympathetic venoconstriction due to the MSFP? why?
it increases it because there is now the blood volume is contained in a smaller cardiovascular system
cwhat does sympathetic arteriolar vasoconstriction due to the MSFP? why?
vasoconstriction in the arteries has a negligable or no effect on the MSFP because the arterioles contain a much smaller quantity of blood
what is the length of the cardiac cycle?
0.8-1.0 seconds
what are the 4 phases that the cardiac cycle is generally split into?
- Filling phase
- Isovolumetric contraction phase
- ejection phase
- Isovolumetric relaxation phase
what does the P wave in a EKG correspond to?
atrial depolarization
what does the QRS complex in a EKG correspond to?
ventricular depolarization
what does the T wave in a EKG correspond to?
ventricular repolarization
what does the TP segment correspond to?
ventricular diastole- at the end of which atrial depolarization produces the P wave of the EKG
what does the ST segment correspond to?
the plateau phase- phase 2
what produces the QRS complex?
upstrokes of all the ventricular action potentials
if the left ventricle falls from 120 mL to 50 mL during the ejection phase, what was the stroke volume?
70 mL
what is the normal ejection fraction for a healthy person?
58% in notes 60% he said in class 55% we heard in a different class
who f-ing knows
when does most ventricular filling occur?
during early diastole as soon at the mitral and tricuspid valves open
what is the role of atrial systole in regards to ventricular volume?
produces only a small rise in pressure for both R. and L. hearts and responsible only for a SMALL increase in ventricular volume
when does atrial diastole occur?
during ventricular systole
when does diastole begin?
at the dichrotic notch when the aortic valve closes (also when the pulmonary valve closes)
explain how the ventricular pressure decreases while the ventricular volume is increasing?
the forward momentum of the blood entering the ventricles distends the ventricles, EXPANDING THEM and DROPPING the pressure even though the ventricular blood volume is increasing
explain the difference between the rapid ejection and the slow ejection phase
- rapid ejection- ventricular pressure is greater than aortic pressure so they blood opens the valve and rushes into the aorta
- slow ejection phase- ventricular pressure falls very rapidly, and actually falls BELOW the aortic pressure! dont worry though- the blood continues to flow due to the forward momentum but it is slowed down due to the reverse pressure gradient
during the filling phase, what is state of the tricuspid valvue? mitral valve?
both are open!
what do the 2 sounds in the cardiac cycle correspond to?
- First heart sound at the closure of the AV valves
- Second heart sound at the closure of the aortic and pulmonary valves
in a jugular pulse reading, what do the following waves correspond to?
A:
C:
V:
A: atrial contraction
C: closure of tricuspid valve
V: atrial filling & emptying
what is the function of the Wigger’s diagram?
it Summarizes the time course of aortic, atrial and ventricular pressures, valve motions, heart sounds, left ventricular volume, jugular pulse and EKG during the cardiac cycle
what does increased contractility and increased preload do to stroke volume?
both of these variables increase SV
