Topic 2 Flashcards

1
Q

To maintain homeostasis, blood must flow across a resistance propelled by –

A

pressure developed by the heart

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2
Q

describe pressure of large valves

A

low pressure

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3
Q

describe the size of in flow valves (AV valves)

A

large

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4
Q

examples of small outflow valves

A

pulmonary and aortic semilunar valves

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5
Q

describe a result of the varying fiber orientation from endocardium to epicardium

A

small sarcomere shortening –> large changes in chamber volume

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6
Q

Name one way the fiber orientations of muscle layers improve efficiency of pumping action

A

heart chamber needs to twist and rotate to squeeze out blood

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7
Q

Where is the blood supply to the heart?

A

coronary arteries on epicardium

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8
Q

What % of the body is the energy demand of the heart?

A

10

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9
Q

The heart produces ATP and is 60-90% – with no stored reserves

A

fatty acid beta oxidative

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10
Q

function of working cells

A

contract in ventricles and atria

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11
Q

function of pacemaker cells

A

spontaneously depolarizing cells that initiate AP in SA and AV nodal cells

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12
Q

function of conducting cells

A

conduct AP at specific rates to specified regions of working cells

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13
Q

how are myocytes physically connected?

A

intercalated disks

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14
Q

how are myocytes electrically connected?

A

gap junctions

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15
Q

what is total force?

A

force measured at isometric contraction peak

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16
Q

what is active force?

A

force generated by cross-bridges (total-passive)

17
Q

what is passive force?

A

force measured when muscle is at rest

18
Q

In addition to the ECM, what is the primary source of resting tension?

19
Q

Which striated muscle is stiffer?

20
Q

Where are Length-tension curves are derived from?

A

multiple isometric twitch contractions (at diff lengths)

21
Q

What sarcomere length range does maximal active force occur?

A

2-2.2 micrometer

22
Q

Preload

A

load that stresses a resting muscle before it is stimulated

23
Q

afterload

A

load encountered after muscle is stimulated and starts to contract

24
Q

what does the velocity of muscle shortening depend on?

25
light load = -- velocity
fast
26
most muscle contractions are --
afterloaded isotonic contractions
27
what can be directly measured from the heart and circulation to gauge its function?
stress, velocity, work
28
stress =
force/area
29
what is the common stress of heart?
2-4 kg/cm^2
30
velocity =
length/time
31
work =
force x length
32
blood pressure determines --
afterload
33
Why is the LV wall thicker than the RV wall?
Thicker wall to meet pressure demands (4x P)
34
persistent higher pressure -->
higher wall tension
35
pressure =
force/tension
36
Law of Laplace correlates mechanical info from hear wall (cells) to --
chamber pressures and volumes