Heart as a pump

Question 1

How many times greater is the resistance in the rest of the body than the lungs?

Answer 1

6x

Question 2

What are the atria sometimes referred to?

Answer 2

The priming pumps

Question 3

priming pumps function

Answer 3

pumps blood over a short distance into the ventricles- ventricle will fill spontaneously due to elastic walls causing recoil

ensures the ventricles are filled

Question 4

How do all the cells contract at once?

Answer 4

gap junctions between cells forming an electrical syncytium

Question 5

Negative aspect of electrical syncytium

Answer 5

arrhythmias will also be propagated

Question 6

What causes heart sounds?

Answer 6

Opening and closing of valves

Question 7

Two layers of heart cells

Answer 7

subendocardial myocytes and subepicardial myocytes

Question 8

Apex beat definition

Answer 8

When the heart rotates and moves forwad, causing the apex to tap against the 5th intercostal space during systole

Question 9

What can the apex beat be used to diagnose?

Answer 9

cardiomegaly, due to the lateral or inferior displacement of the apex beat suggesting that the heart has become enlarged

Question 10

isovolumetric phase definition

Answer 10

ventricular pressure sufficient to close inlet valve but not sufficient to open outlet valve

Question 11

Cardiac cycle definition

Answer 11

the sequence of events that occurs in a single heartbeat. The cycle has two main phases of systole and diastole and is complete in around 1 second at rest

atrial systole- ventricular systole- ventricular diastole

Question 12

Why do elderly people require atria more than young? + how much they contribute?

Answer 12

Elastic hearts are able to recoil to collect blood, do not need the atria to completely fill the ventricles

ventricles more stiff and fibrotic, thus cannot depend on recoil

10-20% in young
50% in old

Question 13

How many isovolumetric phases are there in one cardiac cycle?

Answer 13

2

Question 14

murmur definition

Answer 14

sound that emits when there is a fault with the valves

Question 15

Two iconic heart sounds + what causes them

Answer 15

lub- AV valves shutting during ventricular systole

dub- semilunar valves shutting during atrial systole

Question 16

What is the jugular venous pulse?

Answer 16

the indirectly observed pressure over the venous system via the visualisation of the internal jugular vein at the semi supine angle

Question 17

why does the vein pulse?

Answer 17

very close to the right atrium and so the atrial pressure cycle creates a visible pulse

Question 18

explain the shape of the pulse recordings

Answer 18

two main pressure waves per cycle named A and V and a smaller peak called C

two sharp falls called C and Y descents

A- increase in pressure caused by atrial systole, raising central venous pressure to maximum of 3-5mmHg, very little backflow

C- wave caused by the bulging of cusps of the tricuspid or mitral valve into the atrium as the valves close. Also caused by stoic expansion of the adjacent carotid artery. Jugular veins are some way away from the right atrium hence the time delay

X descent- sharp fall in pressure due to atrial relaxation and downwards movement of the annulus fibrosis as it contracts. The downward movement of the base stretches the atria and sucks blood into them, reaching peak velocity of venous inflow

V wave- atrial pressure rises due to filling, occurs during ventricular systole

Y descent- AV valves open as a result of build up of atrial pressure exceeding ventricles, rapid drainage leads to drop in pressure

Question 19

important muscles in valve function

Answer 19

papillary muscles

Question 20

papillary muscle structure + function

Answer 20

inward projections of the ventricular wall which contract and tense the chord tendineae during systole which prevents the valves from inverting into the atria as pressure builds up in the ventricle

Question 21

ejection fraction definition + value at rest

Answer 21

the percentage of blood leaving the ventricles compared to total possible volume of blood that could be ejected

50%

Question 22

how are heart sounds formed?

Answer 22

cardiac valves close, where the cusps balloon back as they check the momentum of there fluxing blood

the sudden tensing of the cusps sets up a brief vibration which is transmitted through the tissues to the chest wall and can be heard through a stethoscope

Question 23

what is heard with healthy valves?

Answer 23

only the closure, not the opening

Question 24

explain first heart sound

Answer 24

lubb

caused by the vibration from the near simultaneous closure of the tricuspid and mitral valves at the start of ventricular systole

Question 25

explain second heart sound

Answer 25

dupp

caused by the closure of the aortic and pulmonary valves as left ventricular pressure falls below that of the outflow vessels, at the end of ventricular systole/beginning of diastole

Question 26

what can the second heart sound sometimes appear like + why?

Answer 26

split second sound due to the initial aortic and a fractionally delayed pulmonary compartment