Lecture 11- Circulation of the Blood Flashcards

1
Q

function of the cardiovascular system

A

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

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2
Q

how is the cardiovascular system able to carry out its function

A

through generating pressure differentials across tissues to enable capillary exchange

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3
Q

hemodynamics

A

the physics of blood flow

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4
Q

what is the flow of blood determined by

A

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

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5
Q

Darcy’s Law

A

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

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6
Q

the greater the difference in pressure….

A

the faster the rate of flow

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7
Q

the more resistance….

A

the smaller the rate of flow

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8
Q

rate of flow is directly proportional to?

A

pressure difference but indirectly proportional to the resistance

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9
Q

what are the 4 factors that affect the rate of flow

A

pressure
viscosity
vessel length
vessel radius
vascular resistance

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10
Q

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

A

r^4

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11
Q

how does low viscosity affect resistance and flow

A

low viscosity means decreased resistance therefore increased flow

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12
Q

how may blood have a high viscosity

A

high red blood cell or protein content

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13
Q

how does a high viscosity affect resistance and flow

A

increases resistance therefore decreases flow

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14
Q

what factors affect resistance

A

vessel length, blood viscosity and vessel radius

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15
Q

in which vessel is the rate of flow the slowest

A

capillaries

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16
Q

which circuit does the right side of the heart do

A

pulmonary circuit

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17
Q

which circuit does the left side of the heart control

A

systemic circut

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18
Q

what generates the pressure gradient

A

contraction of the heart muscles

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19
Q

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

A

2-6mmHg

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20
Q

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

21
Q

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

22
Q

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

23
Q

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

A

100-140mmHg

24
Q

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

25
circulation of blood
heart->tissues->heart
26
where is blood pressure measured
brachial artery
27
what do the numbers of blood pressures represent
first number- max pressure in the artery during the cardiac cycle (systolic) second number- min pressure in artery during the cardiac cycle (diastolic)
28
what is low blood pressure also known as
hypotension
29
what is high blood pressure known as
hypertensive
30
dicrotic notch
closure of the aortic valve during the elastic recoil in the arteries
31
mean arterial pressure
average blood pressure in the artery during one cardiac cycle
32
how to calculate man arterial pressure
DBP (diastolic blood pressure) +1/3 pulse pressure
33
how to calculate pulse pressure
systolic - diastolic pressure
34
how long is the hear in diastole and systole for
diastole-2/3 systole-1/3
35
the cardiac cycle
a series of electrical (cardiac conducting system) and mechanical events determining blood flow through the heart and into the circulation during one heartbeat
36
what occurs during systole
contraction -> ejection
37
what occurs during diastole
relaxation -> filling -repolarisation of the cells
38
what are electrical events of the heart measured by
ECG
39
outline of the cardiac conducting system
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
40
ECG
detects electrical activity (ionic movement) across the heart it is an amalgamation of all the action potentials occurring in the heart
41
P wave
atrial depolarisation (contraction)
42
QRS complex
Ventricular depolarization (contraction) atrial repolarisation also occurs at this stage but is masked by ventricular contraction (doesn't appear on the trace)
43
T wave
ventricular repolarisation (relaxation)
44
why is diastole much longer than systole
maximises the time for the heart to fill with blood
45
what is the first heart sound (lub)
sound of the AV valves closing
46
What occurs during the isovolumic contraction phase of ventricular systole?
Ventricles contract with no volume change as all valves are closed, sharply increasing pressure
47
what is the second heart sound (dub)?
sound of aortic valve/ semilunar valves closing
48
What occurs during the isovolumic relaxation phase of ventricular diastole?
Ventricles relax without changing volume, as all valves are closed and pressure decreases
49
late diastole
atria and ventricles relaxed