Lecture 5 - Regulation Of Flow In Heart

Question 1

How many chambers are there of the heart?

Answer 1

4 chambers

2 atria and 2 ventricles

Question 2

Where does atria pump blood to?

Answer 2

Ventricles

Atria are smaller and thinner than ventricles

Question 3

Where does ventricles pump blood from?

Answer 3

Heart

Ventricles are larger and stronger

Question 4

Where does the deoxygenated blood returning from the body enter heart via?

Answer 4

Superior and inferior vena cava

Question 5

Where does the blood from atria pump to and through what valve?

Answer 5

The blood enters the right atrium
Valve - tricuspid valve
Pumped to the right ventricle

Question 6

Where is blood pumped to from the right ventricle?

Answer 6

Pulmonary artery

Valve = pulmonary semi-lunar valve

Question 7

Where does the pulmonary artery carry blood to?

Answer 7

Lung

Function: releases carbon dioxide and absorb oxygen

Question 8

How does the blood in lungs return to the heart?

Answer 8

Pulmonary veins

Question 9

From the pulmonary vein where does the blood enter the heart?

Answer 9

Left atrium

Question 10

The left atrium contract to pump blood where?

Answer 10

Left ventricle

Question 11

Where does the left ventricle pump blood to?

Answer 11

Aorta

Valve = aortic semilunar valve

Question 12

From the aorta where does the aorta blood enter?

Answer 12

systemic circulation
Throughout body tissues
Returns to heart via vena cava

Question 13

What is aorta?

Answer 13

Artery that carries blood away from the left ventricle

Question 14

Describe the conduction system of heart?

Answer 14

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

Question 15

P wave of Wiggers Diagram

Answer 15

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)

Question 16

QRS complex of Wiggers Diagram

Answer 16

Depolarisation of ventricle muscle
AV valves snap shut (luv sound)
Ventricular pressure increases dramatically (open aortic and pulmonary valve)
Ventricular volume decreases

Question 17

T wave of Wiggers Diagram

Answer 17

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

Question 18

Isovolumetric contraction

Answer 18

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

Question 19

Ejection (Wiggers Diagram)

Answer 19

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

Question 20

Isovolumetric relaxation?

Answer 20

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

Question 21

Rapid filling

Answer 21

With mitral valve open, blood rapidly flows intro ventricle

Rise in atrial pressure due to continuous venous filling of atria

Question 22

What is Atrial systole?

Answer 22

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

Question 23

What is Diastasis?

Answer 23

When the pressure in ventricle approaches that of atrium, they act as a single chamber and very little/no blood is filled into ventricle

Question 24

When is the aortic valve open?

Answer 24

Ventricular pressure > aortic pressure

Question 25

What can be plotted against each other?

Answer 25

Pressure and volume

Question 26

What is the pressure volume loop for a left ventricle?

Answer 26

1. AV valve open (mitral valve)
2. Ventricular filling occurs, volume increases and pressure increases as blood enters
3. Atrial contraction completes ventricular filling (EDV is reached at end of this phase)
4. The AV node closed
5. Isovolumetric ventricular contract occurs
   Volume remain constant, pressure increases markedly
6. Aortic valve open
7. Stroke volume of blood is ejected, as blood leaves, volume decreases as pressure peaks
8. Aortic valve closes
9. Isovolumetric ventricular relaxation
   Volume remain constant
   Pressure falls rapidly

Question 27

Where does an increase in inotropy shift EDPVR?

Answer 27

Up and left

Increase stroke volume, decrease ESV

Question 28

Where does decrease in inotropy shift EDPVR?

Answer 28

Right

Decrease stroke volume and increase ESV

Question 29

What is isovolumetric contraction?

Answer 29

The ventricles contract with no corresponding volume changes