BMS10-1024 Cardiac Function 1 Flashcards
What happens when the heart gets over stretched?
Contractile force is weaker as myosin and actin aren’t overlapping so SV is decreased
Where is the dicrotic notch?
After the Pulmonary valve shuts
Atrial systole account for how much ventricular filling?
Less than 20%
How does the rest of the ventricle get filled?
Elastic recoil
Describe the atria wave (3)
Atria contracts
Mitral valve shuts as ventricles contract
Blood flows back into the atria
Mitral valve opens
How do you find the stroke volume from a ventricular volume graph?
Distance vertically between LVEDV and RVEDV
P
Atrial depolarisation
QRS
Ventricular depolarisation
T
Ventricular repolarisation
Describe the 4 sounds due to the heart
Ventricles contract
Pulmonary/aortic valves shut
Mitral and tricuspid valves open
Atrial contract
When is atrial contracting heard?
With a raised end diastolic pressure
What causes murmurs?
Turbulent blood
2 causes of murmurs
Narrowing
Valve incompetence
What can cause valve incompetence?
Inflammed heart muscles and valves due to bacteria e.g. gum disease or dental procedures
What 2 factors influences stroke volume?
Energy of contraction of ventricles
Left ventricular resistance to outflow
What decides the energy of ventricular contraction?
Diastolic stretch (preload) Sympathetic innervation
Which equation is diastolic stretch linked to?
Frank Starling law
What does resistance to outflow mean?
The pressure the heart is working against in the arteries during ventricular systole to eject the blood- total peripheral resistance (afterload)
What does an increased preload do? (2)
Increases ventricular pressure and contraction force
What is Frank Starling’s law?
Heart contraction force increases due to diastolic stretching
The energy released in contraction depends on the initial fibre length and how much these have become stretched during filling
What happens if the heart is over stretched?
Reduce contractile force and so SV
What happens with increased sympathetic stimulation?
EDP stays the same but SV increases
On the starling graph what are the axis?
SV vs EDP
Can the 2 halves of the heart have different SV?
No we have a closed system so if one side spits out more and increases the SV the other side will just have to receive that increased amount and also increase its SV
