The Heart As A Pump Flashcards
What are the 4 heart valves from the right hand side to the left hand side?
Tricuspid valve (atrioventricular valve)
Pulmonic valve (semilunar valve)
Mitral valve (atrioventricular valve)
Aortic valve (semilunar valve)
What are the 4 chambers of the heart?
Right atrium
Right ventricle
Left atrium
Left ventricle
How is the heart a pump?
It is made up of 2 pumps acting in series
What pressure is pulmonary circulation?
Low pressure
What pressure is systemic circulation?
High pressure
What is Systole?
Contraction and ejection of blood from the ventricles
What is Diastole?
Relaxation and filling of the ventricles
How many leaflets does the tricuspid valve, pulmonic valve and the aortic valve have?
3 leaflets
How many leaflets does the mitral valve have?
2
Also called the Bicuspid valve
How does the thickness of the left ventricle compare to the right ventricle and why?
Left is much thicker
Systemic circulation is at a much higher pressure since it needs to pump blood around the body
What is stroke volume?
The volume of blood ejected from each ventricles per heart beat
What is the volume of blood in the average 70kg male?
5L
What is the stroke volume for the average 70kg man at rest?
70ml per beat
How are cardiac myocytes interconnected electrically?
Via intercalated discs (contain gap junctions)
What are the visible features of cardiac muscle?
Striated
Intercalated discs
Branched
Single central nuclei
What causes the opening and closing of the heart valves?
Changes in pressure between the chambers of the heart
What is the function of the chordae tendineae?
Prevents the valves from inverting leading to blood leaking back into chambers in the heart
When the aortic valve is open, is the mitral valve open or closed and why?
Mitral/Bicuspid valve closed
If aortic valve is open it means ventricular systole is occurring, mitral is closed to prevent blood flowing back into the left atria
What region of the heart are the pacemaker cells found?
Sinoatrial node
What is the role of the specialised cardiomyocytes in the sinoatrial node?
Initiate and spread action potentials
What is meant by the cells in the Sinoatrial node have autorhythmisicty?
The auto rhythmic cells of the SAN initiate their own action potential and the rest of the auto rhythmic cells of the heart conduct the action potential throughout the heart
Once the action potential has been generated at the SAN what happens next?
Action potential/wave of depolarisation spreads through the atria to the Atrioventricular node (AVN)
What is the function of the Atrioventricular Node (AVN)?
Initiates a time delay before the action potential is conducted to the ventricles
Why is the time delay initiated by the AVN important?
Gives time for the atria to finish contraction before the ventricles contract
Following the AVN, how is the action potential conducted?
Down the Bundle of His, then to the bundle branches (left and right) which run down the septum to the apex of the heart where Purkinje fibres conduct the depolarisation to the ventricles
How do the ventricles contract?
From the apex upwards
What are the 7 phases of the Cardiac cycle?
Atrial Contraction
Isovolumetric Contraction (ventricles)
Rapid Ejection (ventricles)
Reduced Ejection (ventricles)
Isovolumetric Relaxation (ventricles)
Rapid Filling (ventricles)
Reduced Filling (ventricles)
In terms of Diastole and systole, how are they affected when heart rate needs to increase?
SYSTOLE = ALWAYS SAME
DIASTOLE = SHORTER
What is a Wiggers diagram?
Diagram that illustrates changes in blood pressure and volume in the left side of the heart for each cardiac cycle
How many heart beats are there per cardiac cycle?
1 heart beat
How would a Wiggers diagram from the right hand side of the heart compare to the left hand side of the heart?
Lower pressures for the RHS
In an electrocardiogram, what does the P wave represent?
Contraction of the Atria/atrial depolarisation