Lecture 5 - Regulation Of Flow In Heart Flashcards
How many chambers are there of the heart?
4 chambers
2 atria and 2 ventricles
Where does atria pump blood to?
Ventricles
Atria are smaller and thinner than ventricles
Where does ventricles pump blood from?
Heart
Ventricles are larger and stronger
Where does the deoxygenated blood returning from the body enter heart via?
Superior and inferior vena cava
Where does the blood from atria pump to and through what valve?
The blood enters the right atrium
Valve - tricuspid valve
Pumped to the right ventricle
Where is blood pumped to from the right ventricle?
Pulmonary artery
Valve = pulmonary semi-lunar valve
Where does the pulmonary artery carry blood to?
Lung
Function: releases carbon dioxide and absorb oxygen
How does the blood in lungs return to the heart?
Pulmonary veins
From the pulmonary vein where does the blood enter the heart?
Left atrium
The left atrium contract to pump blood where?
Left ventricle
Where does the left ventricle pump blood to?
Aorta
Valve = aortic semilunar valve
From the aorta where does the aorta blood enter?
systemic circulation
Throughout body tissues
Returns to heart via vena cava
What is aorta?
Artery that carries blood away from the left ventricle
Describe the conduction system of heart?
Starts with pacemaker: sinoatrial node inferior to superior vena cava
The SA node signals electrical impulse wave over walls of atria causing it to contract (systole)
The signal from SAN is picked up by mass of conduction tissue know as AV node
AV node picks up signal and transmit the signal through AV bundle
Purkinje fibres carry impulse down Bundle of His to Apex so that the ventricles contract upwards
P wave of Wiggers Diagram
Start at P wave
Depolarisation of atria
Atrial pressure and ventricular volume increases
Passive and active filling of ventricles would also increase Ventricular pressure and volume
Aortic pressure would still be falling because
Aortic pressure > left ventricular pressure (aortic valve shut)
QRS complex of Wiggers Diagram
Depolarisation of ventricle muscle
AV valves snap shut (luv sound)
Ventricular pressure increases dramatically (open aortic and pulmonary valve)
Ventricular volume decreases
T wave of Wiggers Diagram
Repolarisation of ventricles
Aortic pressure > ventricular pressure (aortic valve close - dub sound)
Ventricular pressure fall below atrial pressure (filling of ventricles)
Aortic pressure gradually fall due to blood entering peripheral arteries and arteriolar
Isovolumetric contraction
Although ventricles contracting, the volume doesn’t change
As ventricles contract, ventricular pressure rises rapidly
Mortal valve close
End of Phase, ventricular pressure > aortic pressure
Aortic valve open
Ejection (Wiggers Diagram)
As the aortic valve open, blood injected rapidly into aorta
Rapid drop in ventricular volume
Pressure gradually rises in atrium (fill via venous pressure against closed mitral valve)
Aortic and ventricular phase drop and T wave appear on ECG
Isovolumetric relaxation?
Volume is constant
Ventricles are at rest
At its lowest value ventricular pressure rapidly drops and during this phase when atria pressure is matched mitral valve open
Repolarisation of ventricular myocardium complete
Rapid filling
With mitral valve open, blood rapidly flows intro ventricle
Rise in atrial pressure due to continuous venous filling of atria
What is Atrial systole?
Atrial contraction - small rise in atrial pressure
Mitral valve is ope
Aortic valve closed
At end of Atrial systole - ventricles is at its max volume
What is Diastasis?
When the pressure in ventricle approaches that of atrium, they act as a single chamber and very little/no blood is filled into ventricle
When is the aortic valve open?
Ventricular pressure > aortic pressure
What can be plotted against each other?
Pressure and volume
What is the pressure volume loop for a left ventricle?
- AV valve open (mitral valve)
- Ventricular filling occurs, volume increases and pressure increases as blood enters
- Atrial contraction completes ventricular filling (EDV is reached at end of this phase)
- The AV node closed
- Isovolumetric ventricular contract occurs
Volume remain constant, pressure increases markedly - Aortic valve open
- Stroke volume of blood is ejected, as blood leaves, volume decreases as pressure peaks
- Aortic valve closes
- Isovolumetric ventricular relaxation
Volume remain constant
Pressure falls rapidly
Where does an increase in inotropy shift EDPVR?
Up and left
Increase stroke volume, decrease ESV
Where does decrease in inotropy shift EDPVR?
Right
Decrease stroke volume and increase ESV
What is isovolumetric contraction?
The ventricles contract with no corresponding volume changes
