Lecture 11- Circulation of the Blood

Question 1

function of the cardiovascular system

Answer 1

maintain an adaptable supply for blood to tissues in order to supply nutrients and signalling molecules and remove waste

Question 2

how is the cardiovascular system able to carry out its function

Answer 2

through generating pressure differentials across tissues to enable capillary exchange

Question 3

hemodynamics

Answer 3

the physics of blood flow

Question 4

what is the flow of blood determined by

Answer 4

the pressure difference between A and B
the resistance to flow (R)

Question 5

Darcy’s Law

Answer 5

flow of a fluid through a porous medium
flow=change in pressure/resistance

Question 6

the greater the difference in pressure….

Answer 6

the faster the rate of flow

Question 7

the more resistance….

Answer 7

the smaller the rate of flow

Question 8

rate of flow is directly proportional to?

Answer 8

pressure difference but indirectly proportional to the resistance

Question 9

what are the 4 factors that affect the rate of flow

Answer 9

pressure
viscosity
vessel length
vessel radius
vascular resistance

Question 10

what is flow directly proportional to (in terms of radius)

Answer 10

r^4

Question 11

how does low viscosity affect resistance and flow

Answer 11

low viscosity means decreased resistance therefore increased flow

Question 12

how may blood have a high viscosity

Answer 12

high red blood cell or protein content

Question 13

how does a high viscosity affect resistance and flow

Answer 13

increases resistance therefore decreases flow

Question 14

what factors affect resistance

Answer 14

vessel length, blood viscosity and vessel radius

Question 15

in which vessel is the rate of flow the slowest

Answer 15

capillaries

Question 16

which circuit does the right side of the heart do

Answer 16

pulmonary circuit

Question 17

which circuit does the left side of the heart control

Answer 17

systemic circut

Question 18

what generates the pressure gradient

Answer 18

contraction of the heart muscles

Question 19

what is the pressure of the atrium during systole in the pulmonary circuit

Answer 19

2-6mmHg

Question 20

what is the pressure of the ventricles during systole in the pulmonary circuit

Answer 20

15-30mmHg

Question 21

what is the pressure of the ventricle during diastole in the pulmonary circuit

Answer 21

3-8mmHg

Question 22

what is the pressure of the atrium in the systemic circuit during systole

Answer 22

6-12mmHg

Question 23

what is the pressure of the ventricle in the systemic circuit during systole

Answer 23

100-140mmHg

Question 24

what is the pressure of the ventricle in the systemic circuit during diastole

Answer 24

3-12mmHg

Question 25

circulation of blood

Answer 25

heart->tissues->heart

Question 26

where is blood pressure measured

Answer 26

brachial artery

Question 27

what do the numbers of blood pressures represent

Answer 27

first number- max pressure in the artery during the cardiac cycle (systolic)
second number- min pressure in artery during the cardiac cycle (diastolic)

Question 28

what is low blood pressure also known as

Answer 28

hypotension

Question 29

what is high blood pressure known as

Answer 29

hypertensive

Question 30

dicrotic notch

Answer 30

closure of the aortic valve during the elastic recoil in the arteries

Question 31

mean arterial pressure

Answer 31

average blood pressure in the artery during one cardiac cycle

Question 32

how to calculate man arterial pressure

Answer 32

DBP (diastolic blood pressure) +1/3 pulse pressure

Question 33

how to calculate pulse pressure

Answer 33

systolic - diastolic pressure

Question 34

how long is the hear in diastole and systole for

Answer 34

diastole-2/3
systole-1/3

Question 35

the cardiac cycle

Answer 35

a series of electrical (cardiac conducting system) and mechanical events determining blood flow through the heart and into the circulation during one heartbeat

Question 36

what occurs during systole

Answer 36

contraction -> ejection

Question 37

what occurs during diastole

Answer 37

relaxation -> filling
-repolarisation of the cells

Question 38

what are electrical events of the heart measured by

Answer 38

ECG

Question 39

outline of the cardiac conducting system

Answer 39

sinoatrial node (pacemaker cells) -50msec

atrioventricular node (cell-cell conduction across atria/ 100 msec delay through AV node allows atrial contraction)-150msec

Bundle of His (Rapid conduction for coordinated ventricular contraction )

ventricular myocardium-225 msec

Question 40

ECG

Answer 40

detects electrical activity (ionic movement) across the heart
it is an amalgamation of all the action potentials occurring in the heart

Question 41

P wave

Answer 41

atrial depolarisation (contraction)

Question 42

QRS complex

Answer 42

Ventricular depolarization (contraction)
atrial repolarisation also occurs at this stage but is masked by ventricular contraction (doesn’t appear on the trace)

Question 43

T wave

Answer 43

ventricular repolarisation (relaxation)

Question 44

why is diastole much longer than systole

Answer 44

maximises the time for the heart to fill with blood

Question 45

what is the first heart sound (lub)

Answer 45

sound of the AV valves closing

Question 46

What occurs during the isovolumic contraction phase of ventricular systole?

Answer 46

Ventricles contract with no volume change as all valves are closed, sharply increasing pressure

Question 47

what is the second heart sound (dub)?

Answer 47

sound of aortic valve/ semilunar valves closing

Question 48

What occurs during the isovolumic relaxation phase of ventricular diastole?

Answer 48

Ventricles relax without changing volume, as all valves are closed and pressure decreases

Question 49

late diastole

Answer 49

atria and ventricles relaxed