CV 1

Question 1

Inotropy definition

Answer 1

Strength of contraction

Question 2

Chronotropy definition

Answer 2

rate of contraction

Question 3

Lusitropy definition

Answer 3

Relaxation

Question 4

Dromotropy definition

Answer 4

Conduction

Question 5

Bathmotropy definition

Answer 5

Excitability

Question 6

The heart pumps how much blood

Answer 6

6 L/min
8640 L/day
2282. Gallons/day

Question 7

CO =

Answer 7

CO = HR x SV

Question 8

SV =

Answer 8

SV = EDV - ESV

Question 9

MAP =

Answer 9

MAP = CO x TPR
MAP = 2x DBP + SBP / 3

Question 10

F ( Tissue Blood flow ) =

Answer 10

F = MAP / VR

Question 11

of Nucleus in cardiac myocytes

Answer 11

1 per myocyte

Question 12

Titin

Answer 12

~ Giant Protein
~ Bungee cord of the heart
~ molecular spring that functions as passive elasticity for the muscle (striated muscle)

Question 13

What are Titans made of

Answer 13

Immunoglobulins

Question 14

Intercalated disks are comprised of:

Answer 14

Fascia Adherens
Desmosomes
Gap Junctions

Question 15

What do Fascia Adherens do

Answer 15

~ Anchoring sites for myocyte
~ Connect to the closest myocyte

Question 16

What do Desmosomes do

Answer 16

~ Specialized for cell to cell adhesion
~ Resist searing forces

Question 17

What do Gap Junctions do

Answer 17

~ Think electrical
~ Allow Ads to spread between cardiac cells - permits ion passages
~ Connexons: specialized tunnels

Question 18

What separates the Atrial syncytium and Ventricular syncytium?

Answer 18

Thick fibrous connective tissues

Question 19

What is the Cardiac Muscle controlled by

Answer 19

ANS

Question 20

length of cardiac action potential

Answer 20

200 msec

Question 21

Resting membrane potential of cardiomyocyte is

Answer 21

-90 mV

Question 22

What maintains -90mV of the cardiiomyocyte?

Answer 22

constant outward leak of K+ through - inward rectifier channels

Question 23

Phase 0

Answer 23

Depolarization
~ Threshold is reached at -70 mV activating fast Na+ channels
~ Rapid depolarization
~ L-type Ca+ channels open at -40 mV
~ Overshoot to +30

Question 24

Phase 1

Answer 24

Early repolarization
~ Some K+ channels open briefly and outward flow of K+ returns TMP to 0 mV

Question 25

Phase 2

Answer 25

Plateau phase ~ L-type Ca2+ channels are still open - small constant influx of Ca2+. Becomes significant in the *** excitation contraction coupling process ~ K+ leaks out - delayed rectifier K+ channels ~ K+ permeability decreases x5 ~ Two currents are electrically balanced at 0 mV

Question 26

Phase 3

Answer 26

Repolarization ~ Ca2+ channels gradually inactivate ~ K+ outflow exceeds Ca2+ inflow. ~ Membrane ionic concentrations are restored by - Na+ - Ca2+ exchanger, - Ca2+ ATPase - Na+ - K+ Atpase

Question 27

Phase 4

Answer 27

Resting membrane potential

Question 28

Number of cardiac T-tubules

Answer 28

1 tubule to 1 SR ( Diad ) ( Triad in skeletal )

Question 29

DHP receptor differences

Answer 29

Electrochemical in cardiac Electromechanical in skeletal

Question 30

Cardiac T tubules

Answer 30

5x diameter in skeletal

Question 31

What does phospholamban do

Answer 31

inhibits re-uptake of calcium into the SR

Question 32

What happens when phospholamban is phosphorylated

Answer 32

When phosphorylated it becomes inactive (disinhibition) increasing Ca++ uptake by the SR (enhances lusitropy)

Question 33

Normal mitral annulus

Answer 33

3 - 3.5 cm

Question 34

Normal aortic annulus

Answer 34

1.8 - 2.3 cm

Question 35

AV valve properties

Answer 35

~ Thin, flimsy, low pressure valves ~ Papillary muscles ~ Chordae Tendinae prevents bulging into atria during contraction

Question 36

Semilunar valve properties

Answer 36

~ Strong yet pliable fibrous tissue ~ Smaller diameter compare to AV valves ~ More rapid ejection and valve closure ~ Prone to mechanical abrasions

Question 37

Total duration of cardiac cycle

Answer 37

70 bpm; 1/70 = 0.014 min/beat or 0.84 sec

Question 38

What is the delay between atria and ventricular contraction? Why?

Answer 38

~ 0.1 seconds ~ To allow for ventricular filling

Question 39

Atria contract ______ second ahead of the ventricles

Answer 39

1/6

Question 40

Resting membrane potential of SA nodal fibers

Answer 40

-55 to -60 mV

Question 41

Why isn't the SA node depolarized all the time?

Answer 41

Ca++ channels become inactive after about 150ms of opening

Question 42

Atrial muscle velocity

Answer 42

0.3m/sec

Question 43

Specialized conduction fiber velocity

Answer 43

1m/sec

Question 44

What 4 Specialized conduction fibers are in the Atria

Answer 44

~ Anterior Interatrial band (Bachman's Bundle) Right atrium to Left Atrium ~ Anterior Internodal Pathway ~ Middle Internodal Pathway ~ Posterior Internodal pathway

Question 45

AV node delay

Answer 45

0.09 sec delay in node

Question 46

AV node location

Answer 46

Posterior wall of right atrium behind tricuspid valve

Question 47

AV bundle delay

Answer 47

0.04 sec delay

Question 48

Conduction travels through the AV node then through the AV bundle what are the associated delays?

Answer 48

~ AV node - 0.09 sec ~ AV bundle - 0.04 sec

Question 49

What causes delay at the AV node and AV bundle

Answer 49

reduction in number of gap junctions between the AV node and the AV bundle (resistance to conduction = slow excitation)

Question 50

Purkinje conduction velocity

Answer 50

1.5 - 4 m/sec ( 6x ventricular muscle conduction velocity)

Question 51

Purkinje fibers are

Answer 51

Large fibers ( larger than ventricular muscle fibers )

Question 52

Conduction velocity from bundle branches to terminating purkinje fibers

Answer 52

0.03 seconds

Question 53

Conduction velocity from endocardium to epicardium

Answer 53

0.03 seconds

Question 54

Conduction velocity from bundle branches to contraction

Answer 54

0.06 seconds

Question 55

What happens with PNS stimulation

Answer 55

ACh is released which increases membrane permeability to K+ This causes hyper-polarization = less excitability ( SA node -65 to -75mV )

Question 56

What happens with SNS stimulation

Answer 56

Release of NE stimulates B1 adrenergic receptors increased membrane permeability of Na+ and CA++ ions ( closer to threshold - decreasing conduction times ) ~ increases nodal discharge ~ increases chronotropy ~ increases isotropy ~increases overall heart activity

Question 57

At rest, O2 consumption by beating heart =

Answer 57

9mL / 100g / min