BMS10-1024 Cardiac Function 1

Question 1

What happens when the heart gets over stretched?

Answer 1

Contractile force is weaker as myosin and actin aren’t overlapping so SV is decreased

Question 2

Where is the dicrotic notch?

Answer 2

After the Pulmonary valve shuts

Question 3

Atrial systole account for how much ventricular filling?

Answer 3

Less than 20%

Question 4

How does the rest of the ventricle get filled?

Answer 4

Elastic recoil

Question 5

Describe the atria wave (3)

Answer 5

Atria contracts
Mitral valve shuts as ventricles contract
Blood flows back into the atria
Mitral valve opens

Question 6

How do you find the stroke volume from a ventricular volume graph?

Answer 6

Distance vertically between LVEDV and RVEDV

Question 7

P

Answer 7

Atrial depolarisation

Question 8

QRS

Answer 8

Ventricular depolarisation

Question 9

T

Answer 9

Ventricular repolarisation

Question 10

Describe the 4 sounds due to the heart

Answer 10

Ventricles contract
Pulmonary/aortic valves shut
Mitral and tricuspid valves open
Atrial contract

Question 11

When is atrial contracting heard?

Answer 11

With a raised end diastolic pressure

Question 12

What causes murmurs?

Answer 12

Turbulent blood

Question 13

2 causes of murmurs

Answer 13

Narrowing

Valve incompetence

Question 14

What can cause valve incompetence?

Answer 14

Inflammed heart muscles and valves due to bacteria e.g. gum disease or dental procedures

Question 15

What 2 factors influences stroke volume?

Answer 15

Energy of contraction of ventricles

Left ventricular resistance to outflow

Question 16

What decides the energy of ventricular contraction?

Answer 16

Diastolic stretch (preload)
Sympathetic innervation

Question 17

Which equation is diastolic stretch linked to?

Answer 17

Frank Starling law

Question 18

What does resistance to outflow mean?

Answer 18

The pressure the heart is working against in the arteries during ventricular systole to eject the blood- total peripheral resistance (afterload)

Question 19

What does an increased preload do? (2)

Answer 19

Increases ventricular pressure and contraction force

Question 20

What is Frank Starling’s law?

Answer 20

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

Question 21

What happens if the heart is over stretched?

Answer 21

Reduce contractile force and so SV

Question 22

What happens with increased sympathetic stimulation?

Answer 22

EDP stays the same but SV increases

Question 23

On the starling graph what are the axis?

Answer 23

SV vs EDP

Question 24

Can the 2 halves of the heart have different SV?

Answer 24

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