Lecture 4- The heart as a pump

Question 1

the heart as a pump

Answer 1

two pumps acting in series - the right first

Question 2

systemic circulation pressure

Answer 2

high

Question 3

pulmonary circulation pressure

Answer 3

low pressure

Question 4

output of the left and right ventricle must be

Answer 4

equal

Question 5

systole

Answer 5

contraction and ejection of blood from ventricles

Question 6

diastole

Answer 6

relaxation and filling of ventricle

Question 7

typical pressure in the right atrium

Answer 7

0-4 mm Hg

Question 8

typical pressure in the right ventricle

Answer 8

25/4 mm Hg

Question 9

typical pressure in pulmonary artery

Answer 9

25/10 mm Hg

Question 10

typical pressure in left atrium

Answer 10

8-10 mm Hg

Question 11

typical pressure in left ventricle

Answer 11

120/10 mm Hg

Question 12

typical pressure in aorta

Answer 12

120/80 mm Hg

Question 13

At rest… each ventricle pumps around ……….ml blood per beat (stroke volume)

Answer 13

70 ml

Question 14

At heart rate of 70bpm= ……..litres blood pumped per minute

Answer 14

4.9 litres

(70ml x 70= 4900 l= 4.9 litres)

(approximate volume of blood in the body)

Question 15

describe basic features of cardiac muscle

Answer 15

• Striated
• Discrete cells interconnected by electrically
• Gap junctions
• Cells contract in response to action potential in the membrane

Question 16

AP cause a rise in

Answer 16

intracellular calcium

Question 17

length of cardiac action potential

Answer 17

relatively long- lasts for duration of a single contraction of heart (280 ms)

Question 18

Action potentials are triggered by

Answer 18

spread of excitation from cell to cell

Question 19

outline the cardiac cycle

Answer 19

1. Return of blood (deoxygenated) from the tissue via the superior (upper parts of the body) and the inferior vena cava int the right atria
2. When pressure is high enough the blood passes down via the tricuspid valve into the right ventricle
3. When ventricles contract look is ejected via the pulmonary valve into the pulmonary artery (deoxygenated blood)
4. Deoxygenated blood pass via the pulmonary artery to the lungs and becomes oxygenated
5. Blood returns to the heart via the pulmonary veins
6. Enters the left atria and into the ventricle via the mitral (bicuspid) valve
7. When ventricles contract the blood is ejected into systemic circulation via the aortic valve

Question 21

heart valves in right side

Answer 21

tricuspid and pulmonary

Question 22

heart valves in left side

Answer 22

mitral

aortic

Question 23

valves open and close depending on

Answer 23

• Open or close depending on differential blood pressure on each side
• Valve cusps are pushed open to allow blood flow and close together to seal and prevent black flow

Question 24

how are the cusps of the mitral and tricuspid valves attached to the papilalry muscle of the heart

Answer 24

via chordinae tendinae (prevent inversion of valves on systole)

Question 25

how to take heart sounds

Answer 25

all physicians take money

Question 26

conduction system of the heart

Answer 26

1. Pacemaker cells in SAN generate AP (pacemaker AP)
   
   • Not neuronal
   • Specialised cardiac myocytes
2. Activity spreads over atria- atrial systole
3. Reaches AVN and delayed 120ms
4. From a-v excitation spreads down septum between ventricles- bundle of his (3 bundles)
5. Next spreads through ventricular myocardium from inner (endocardial) to outer (pericardial) surface

Ventricle contracts from the apex up forcing blood through outflow valves

Question 27

how many phases can the cardiac cycle be split into

Answer 27

7 phases

Question 28

outline the 7 stages of the cardiac cycle

Answer 28

1. Atrial contraction
2. Isovolumetric contraction
3. Rapid ejection
4. Reduced ejection
5. Isovolumetric relaxation
6. Rapid filling
7. Reduced filling

Question 29

When the heart beats faster, the time of systole …………, diastole ………..

Answer 29

systole - stays the same (Duration of Systole is constant )

diastole- shortens

Question 30

systole is roughly how many seconds (67bpm)

Answer 30

0.35s

Question 31

diastole is roughly how many seconds (67bpm)

Answer 31

0.55 s

Question 32

wiggers diagram

Answer 32

In the Wiggers diagram, the X-axis is used to plot time, while the Y-axis contains all of the following on a single grid:

• Blood pressure
  
  • Aortic pressure
  • Ventricular pressure
  • Atrial pressure
• Ventricular volume
• Electrocardiogram
• Arterial flow (optional)
• Heart sounds (optional)

Question 33

wiggers diagram is typically plotted just for the ….. side of the heart

Answer 33

left side of the heart

(right would similar but lower pressure)