The heart as a pump

Question 1

The heart beats every…

Answer 1

1 second and if we know what happens in this one second, we know how the heart beats over a period of time

Question 2

What does the heart need to do?

Answer 2

Develop high pressure

Question 3

Arteries carry…

Answer 3

Blood Away from heart

Question 4

Veins carry blood…

Answer 4

towards the heart

Question 5

Why are there so many tubes

Answer 5

So that the blood is as close as it can be to the tissues

Question 6

Part of the heart that does most of the work

Answer 6

Ventricles

Question 7

What happens during relaxation?

Answer 7

The blood fills the atria and vens as the AV valves are open but others are closed to prevent high P blood from coming in

Question 8

How are the valves controlled?

Answer 8

Not through muscle or nerves, but by Pressure

Question 9

How does cardiac muscle contract?

Answer 9

Same concept as skeletal muscle

Question 10

Why is everything activated in cardiac muscle unlike skeletal

Answer 10

We can vary our force in skel due to recruitment and its a voluntary process

Question 11

How to ^ force of cardiac contraction if all fibres recruited?

Answer 11

Release more Ca2+

Question 12

How do cardiac muscles relax

Answer 12

Decrease in cytosolic Ca2+ levels.
* Ca2+ pumped back into the SR.
* Cross-bridges release when ATP i.e active use of E to relax by changing the myosin head
binds to myosin.
* Reduction in force means the heart
can relax.
* All cardiac myocytes relax each beat.

Question 13

Diastole

Answer 13

Relaxation + falling pressure

Question 14

Systole

Answer 14

Contraction + rising P

Atrial systole before ven

Question 15

How many parts to cardiac cycle

Answer 15

5

Question 16

What happens at the start?

Answer 16

Ven in diastole while atrial systole occurs first

Question 17

Atrial systole

Answer 17

Artrium contract, open AV valves, Passive vens

Question 18

Lubb sound

Answer 18

When P in vens ^ and AV slams shut to prep for ven contraction

Question 19

Isovolumetric ven contraction

Answer 19

All entrances closed but not enough P in vens to open up the semilun valves so V doesnt change even though vens constrict

Question 20

Ven ejection

Answer 20

The P is large enough so semilun valves open

Question 21

Dupp sound

Answer 21

Ca2+ goes away and when the P in vens is less than Aorta and pulm, the semilun shuts to prevent backflow

Question 22

Isovol ven relaxation

Answer 22

Blood fills in atrium but AV valves shut

Question 23

Passive filling

Answer 23

Ven P lower than atrium so AV valves open

Question 24

Features of BP graph

Answer 24

*Pulsatile change in pressure
in the major arteries linked to
ejection of blood
* Periods of systole (rising
pressure) and diastole
(falling pressure)
* Diastole is typically longer
than systole
* Systemic arterial pressure is
much higher than pulmonary
arterial pressure as you need to eject over long distances over multiple branches and back

Question 25

How long in systole and diasole

Answer 25

40% and 60%

Question 26

Features (sys/diastolic p)

Answer 26

*Systolic pressure is the
highest point on the trace
* Diastolic pressure is the
lowest point on the trace
* Pulse pressure is the
difference between the
highest and lowest points
* Mean pressure is the average
across the full cycle but usually a bit lower than the “middle” as the cycle is 60% diastole (not a fair divide)
* Hypertension is high blood
pressure, while hypotension
is low blood pressure

Question 27

What is systolic P

Answer 27

P in arteries when vens contract