integration of cardiac function Flashcards
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
what does afterload due to SV? why? what is an example of when this can happen?
increased after load decreases SV because the end systolic volume will be increased
this can occur if aortic valve diseases and in hypertension
what does increased atrial filling pressure do to SV?
decrease it
what does increased ventricular filling time do to SV?
increases it
what does increased ventricular compliance do to SV?
increases it
what does increased heart rate do to SV?
decreases it
what does increased preload do to SV?
increase it
starling’s principal
what does increased afterload do to SV?
decreases it
which atria contracts first?
right
which ventricle contracts first?
left
describe the contraction of the R ventricle
like bellows
describe the contraction of the L ventricle
like squeezing a toothpaste bottle
which valve closes first: mitral or tricuspid?
mitral
which valve opens first? pulmonary or aortic valve?
pulmonary valve (this is just because the pressure in the pulmonary artery is less)
describe the 1st heart sound
at the closure of the AV valves “lub”
describe the 2nd heart sound
at the closure of the aortic and pulmonary valves “dub”
describe the 3rd heart sound
diastolic filling “gallop”-recoil of the ventricles that have limited compliance
particularly evident in children
describe the 4th heart sound
atrial contraction “gallop”; usually pathogenic
for sympathetic stimulation define each of the parameters: transmitter receptor secondary messenger functional result
transmitter: norepi
receptor: beta 1 on pacemaker and myocytes
secondary messenger: increase cAMP
functional result: tachycardia and increased contractility
for parasympathetic stimulation define each of the parameters: transmitter receptor secondary messagenger functional result
transmitter: acetylcholine
receptor: M2 on pacemakers; minro myocyte effect
secondary messagenger: decreased cAMP
functional result: bradycardia; decreased contractility
compare the CO into the aortic and into the pulmonary artery
they are the same because the systemic and pulmonary systems are in series
when does hypoxia occur?
when the CO falls to 1/3 the normal amount
list some factors that will increase CO
exercise fever anxiety body weight pregnancy hypertyroidism
what are some compensatory mechanisms that will cause CO to increase?
- chronic anemia
- histotoxic hypoxia
- pulmonary disease with hypoxemia
- mild inspiratory hypoxia
list some factors that would decrease CO
aging
severe anoxia
acute hemorrhage
heart disease (body unable to reach the proper CO)
if you decrease right atrial pressure, what effect will this have on venous return?
it will increase it
at normal CO how long should it take the entire blood volume to move around the body?
move around the body once/minute
