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AU14 Physiology > EX 2; The Heart > Flashcards

EX 2; The Heart Flashcards

1
Q

This is a rapid assessment of blood composition; the percent of the blood volume that is composed of RBCs

A

hematocrit; should be roughly 45%

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2
Q

Estimate the hematocrit of a person with a plasma volume of 3L and a total blood volume of 4.5L

A
  1. 5-3 = 1.5L

1. 5/4.5 = 33% hematocrit

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3
Q

The exchange of oxygen, carbon dioxide, nutrients, and metabolic end products occurs at the level of what

A

capillaries

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4
Q

Which portions of the body receive the most blood flow at rest

A

muscle
kidneys
abdominal organs

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5
Q

This is the volume per unit time

A

flow

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6
Q

What is the equation for determining flow

A

change in pressure/resistance

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7
Q

This is how difficult it is for blood to flow between 2 points

A

resistance

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8
Q

What can affect resistance

A

change in radius

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9
Q

What is the equation for resistance

A

8(length)(fluid viscosity(ή))
divided by
Ħ (radius)^4

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10
Q

This can alter the resistance and thereby flow

A

blood viscosity

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11
Q

What causes the heart valves to open and close

A

pressure differences

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12
Q

How does the electrical conduction flow through the heart

A

via gap junctions; allowing it to be very rapid

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13
Q

What is the flow of the electrical current through the heart

A

SA - atria - AV - bundle of His - bundle fibers - ventricles

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14
Q

This is the hearts pacemaker because it initiates each wave of excitation with atrial contraction

A

SA node

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15
Q

What is the role of the bundle of His and other parts of the conduction system

A

deliver the excitation to the apex of the heart so that ventricular contraction occurs in an upward sweep

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16
Q

What is the P

A

atrial depolarization

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17
Q

What is the QRS

A

ventricle depolarization

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18
Q

What is the T

A

ventricle repolarization

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19
Q

What happens to the atrial repolarization

A

it is “lost” in the QRS series

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20
Q

The rapid opening of what is responsible for the rapid depolarization phase

A

voltage gated sodium channels

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21
Q

The prolonged “plateau” of depolarization is due to what

A

the slow but prolonged opening of voltage gated calcium channels plus the closures of the potassium channels

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22
Q

This results in the repolarization phase

A

opening of the potassium channels

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23
Q

These two things cause a threshold graded depolarization in the action potential of an auto rhythmic cardiac cell

A

sodium ions “leaking” in through the F-type (funny) channels plus Ca ions moving through the T channels

24
Q

in the action potential of an auto rhythmic cardiac cell, the rapid opening of this is responsible for the rapid depolarization phase

A

voltage gated calcium channels

25
Q

in the action potential of an auto rhythmic cardiac cell, these two things are responsible for the repolarization plhase

A

reopening of the potassium channels

closing of the calcium channels

26
Q

A myocyte cannot beat outside of the heart, why

A

because it needs the SA node to be active

27
Q

A SA nodal cell will beat outside of the heart, why

A

due to the automaticity of the funny channel; it does not have a resting membrane potential

28
Q

How does the electrical signal transfer to a contractile force

A

excitation-contraction coupling

29
Q

Excitation-contraction coupling links the cardiac muscle cell action potentials to contraction via what

A

control of calcium within the myocardium

calcium induced calcium release

30
Q

The prolonged refractory period of cardiac muscle prevents what two things

A

tetanus

and allows time for the ventricles to fill with blood prior to pumping

31
Q

Cardic activity can be expressed as what

A

cardiac output; in reference to the amount of blood moved per unit of time

32
Q

What is the first heart sound

A

closure of the AV valves

33
Q

What is the second heart sound

A

closure of the aortic and pulmonary valves

34
Q

What are three defects of the heart causing murmurs

A

stenosis = narrowing
regurgitation = insufficiency
septal defects

35
Q

Which portion of the blood flow is in a series; where the components are connected end-to-end

A

pulmonary circuit

36
Q

Which portion of the blood flow is in parallel; where components are connected between the same two sets of electrically common points, creating multiple paths

A

systemic circulation

37
Q

What does the parallel blood flow of the systemic system allow for

A

organs to get 100% of oxygenated blood

38
Q

This is the volume of blood each ventricle pumps per minute or the volume of blood flowing through either the pulmonary or systemic circuit per minute

A

cardiac output

39
Q

What is the equation for cardiac output

A

CO = HR x SV

40
Q

The parasympathetic system acts upon which receptors on the heart

A

muscarinic

41
Q

Does the parasympathetic act on the atria or ventricles

A

atria

muscarininc receptors on the atria

42
Q

What neurotransmitter does the PS release

A

ACh

43
Q

The sympathetic system acts upon which receptors on the heat

A

beta

44
Q

Does the sympathetic act on the atria or ventricles

A

both!

45
Q

What neurotransmitters does the S system release

A

NE and E

46
Q

What two things can be used to speed up heart rate

A

increase sympathetic control; NE and E

decrease parasympathetics control; reduce ACh

47
Q

What are the three factors influencing stroke volume

A

pre-load; the volume of blood in the ventricles just before contraction (end-daistolic volume)
magnitude of sympathetic input to the ventricles
afterload; the pressure against which the ventricles pump

48
Q

What is the Frank-Starling mechanism

A

increasing the stroke volume

49
Q

In which two ways can you increase the stroke volume via Frank-Starling Mechanism

A

fill it more with blood

deliver sympathetic signals

50
Q

What does sympathetic signals do to the contractile force

A

they cause a stronger and more rapid contraction and more rapid relaxation

51
Q

Sympathetic effects cause an increase in this, which increases contraction

A

calcium

52
Q

True or False

It is possible to affect stroke volume without affecting heart rate

A

False; it is not possible, under normal circumstances, to increase SV or HR without influencing the other

53
Q

What are five ways in which to measure cardiac function

A 
thermodultion cardiac output
angiography
echocardiogram
MRI
ejection franction
54
Q

This occurs is 1:500 people, characterized by increased heart all thickening particularly in the inter ventricular septum interfering with blood ejection

A

hypertropic cardiomypathy

55
Q

What are three symptoms of hypertrophic cardiacmyopathy

A

angina
arrhythmyas
sudden cardiac death

AU14 Physiology (24 decks)

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