Lecture 7- Heart Continued

Question 1

Describe the orientation of the heart?

Answer 1

Apex of the heart points inferiorly, anteriorly and to the left
1/3 lies to the right of the midline and 2/3 to the left
Right boarder=RA
Inferior border=RV
Left border = LV
Base= the top where the great vessels come out

Question 2

Describe the hearts ‘bag’

Answer 2

Inner/Visceral Pericardium
Pericardial space/serous fluid
Outer/parietal pericardium
Fibrous pericardium

Question 3

From inside heart to outside?

Answer 3

1. inside ventricle
2. endocardium
3. myocardium
4. epicardium(heart wall) or visceral pericardium(pericardium)
5. Pericardial space/ serous fluid
6. parietal pericardium
7. fibrous pericardium
8. outside pericardial sack

Question 4

Wall puncture?

Answer 4

CARDIAC TAMPONADE

-Blood is forced at high pressure into pericardial space and builds up stopping the heart from functioning.

Question 5

Supportive structures?

Functions?

Answer 5

Fibrous skeleton around:
Aorta + mitral =fully
Tricuspid= partially

Fatty connective tissue around:
Pulmonary =fully
Tricuspid= partially

Act as supportive structures as well as electrical insulators to force depolarisation wave to the AV node

Question 6

Conduction system?

Answer 6

1. SA node
2. AV node
3. AV bundle + purkinje fibres

Question 7

SA node

Answer 7

Point of initiation
SA– atrial muscle
Slow- 0.5m/s
Even atrial contraction

Question 8

AV node

Answer 8

Very slow 0.05m/s

100ms delay between A and V

Question 9

AV bundle

Answer 9

AV– Purkinji fibres
Fast 5m/s
Even ventricular contraction (systole)

Question 10

5 steps of cardiac cycle?

Answer 10

1. Ventricular filling
2. Atrial contraction
3. Isovolumetric Ventricle contraction
4. Ventricle ejection
5. Isovolumetric ventricular relaxation

Question 11

Ventricular filling

Answer 11

Aorta-90

V-

Question 12

Atrial contraction

Answer 12

Tops up the remainder 20% but isn’t necessary
Small pressure rise in Atria
No valves so isn’t that good

Question 13

Isovolumetric V contraction

Answer 13

0.05 seconds
Ventricle begins to contract.
Mitral valve closes and turbulence is 1st heart sound
Ventricle is still below the Aorta(90)

Question 14

Ventricular ejection

Answer 14

Systole of V continues but now Aortic valve opens
Because blood is ejected faster than it can move away the V pressure continues to rise a little bit later in the phase ejection falls as the contractile limit is met and pressure begins to drop

Question 15

Isovolumetric ventricular relaxation

Answer 15

0.05 seconds
Ventricle relaxes and pressure drops suddenly
Flow reverses and aortic valve closes 2nd heart sound
Brief period of time the ventricle is again isolated as the V pressure has not yet fallen below the A pressure

Question 16

Difference between left and right pressure vs cycle

Answer 16

Right side will just have lower pressures, roughly the same shape though

Question 17

Normal blood pressure?

Answer 17

120/80
120- max arterial pressure
80- min arterial pressure

Question 18

Sound 1 and 2?

Answer 18

1- mitral and tricuspid close at the same time

2- pressure difference means the aorta closes slightly sooner as blood rushes out faster so slight double beat sound

Question 19

Left ventricular volumes

Answer 19

Same as the right…
Max is about 120
Min is about 60
Ejection is 60-70ml

Question 20

Left ventricular volume

Answer 20

Changes during systole as flow of blood is affected initially by the body’s ability to accept the rush of blood and then at the end it drops due to a diminishing room for fibres to contract more.

Question 21

Systole

Answer 21

Entire contraction beginning with SA node and Atrial contraction, but V contraction is the main event

Question 22

Atrial diastole

Answer 22

Everything between the contraction. Not limited to just when blood is flowing in/filling

Question 23

First branch off the aorta

Answer 23

Coronary artery