Topic 2

Question 1

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

Answer 1

pressure developed by the heart

Question 2

describe pressure of large valves

Answer 2

low pressure

Question 3

describe the size of in flow valves (AV valves)

Answer 3

large

Question 4

examples of small outflow valves

Answer 4

pulmonary and aortic semilunar valves

Question 5

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

Answer 5

small sarcomere shortening –> large changes in chamber volume

Question 6

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

Answer 6

heart chamber needs to twist and rotate to squeeze out blood

Question 7

Where is the blood supply to the heart?

Answer 7

coronary arteries on epicardium

Question 8

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

Answer 8

10

Question 9

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

Answer 9

fatty acid beta oxidative

Question 10

function of working cells

Answer 10

contract in ventricles and atria

Question 11

function of pacemaker cells

Answer 11

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

Question 12

function of conducting cells

Answer 12

conduct AP at specific rates to specified regions of working cells

Question 13

how are myocytes physically connected?

Answer 13

intercalated disks

Question 14

how are myocytes electrically connected?

Answer 14

gap junctions

Question 15

what is total force?

Answer 15

force measured at isometric contraction peak

Question 16

what is active force?

Answer 16

force generated by cross-bridges (total-passive)

Question 17

what is passive force?

Answer 17

force measured when muscle is at rest

Question 18

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

Answer 18

titin

Question 19

Which striated muscle is stiffer?

Answer 19

cardiac

Question 20

Where are Length-tension curves are derived from?

Answer 20

multiple isometric twitch contractions (at diff lengths)

Question 21

What sarcomere length range does maximal active force occur?

Answer 21

2-2.2 micrometer

Question 22

Preload

Answer 22

load that stresses a resting muscle before it is stimulated

Question 23

afterload

Answer 23

load encountered after muscle is stimulated and starts to contract

Question 24

what does the velocity of muscle shortening depend on?

Answer 24

load

Question 25

light load = – velocity

Answer 25

fast

Question 26

most muscle contractions are –

Answer 26

afterloaded isotonic contractions

Question 27

what can be directly measured from the heart and circulation to gauge its function?

Answer 27

stress, velocity, work

Question 28

stress =

Answer 28

force/area

Question 29

what is the common stress of heart?

Answer 29

2-4 kg/cm^2

Question 30

velocity =

Answer 30

length/time

Question 31

work =

Answer 31

force x length

Question 32

blood pressure determines –

Answer 32

afterload

Question 33

Why is the LV wall thicker than the RV wall?

Answer 33

Thicker wall to meet pressure demands (4x P)

Question 34

persistent higher pressure –>

Answer 34

higher wall tension

Question 35

pressure =

Answer 35

force/tension

Question 36

Law of Laplace correlates mechanical info from hear wall (cells) to –

Answer 36

chamber pressures and volumes