Physio- Chapter 9

Front 1

A continuous successsion of heart contractions that transmits APs throughout the cardiac muscel to cause heart beat

Back 1

cardiac rhythmicity

Front 2

What are three major types of cardiac muscles?

Back 2

atrial, ventricular, and excitatory & conductive

Front 3

Compared to skeletal muscles, cardiac muscles contractions are

Back 3

longer

Front 4

What type of muscle exhibits either autonomic rhythmical electrical discharge in the form of APs or conduction of APs throughout the heart

Back 4

specialized excitatory and conductive muscles

Front 5

Call membranes that seperate individual cardiac muscles from one another

Back 5

Intercalated discs

Front 6

The cell membranes fuse with one another to form

Back 6

Gap junctions

Front 7

The atrial are seperated from ventricles

Back 7

by fibrous tissue that surrounds AV valvular openings

Front 8

How are potentials conducted from the atrial syncytium to the ventricular

Back 8

specialized conductive system (AV bundles)

Front 9

The APs recorded in ventricles

Back 9

105 mv (-85 mv to +20 mv)

Front 10

How long does a cardiac muscles stay depolarized?

Back 10

.2 seconds

Front 11

The AP of skeletal muscles is caused by?

Back 11

fast Na+ channels (Na+ enters from ECM)

Front 12

The AP of cardiac muscles is caused by?

Back 12

1. fast Na+ channels 2. slow Ca 2+ channels (aka Ca2+/Na+ channels)

Front 13

Whay are they called slow Ca 2+ channels?

Back 13

slow to open and opened longer

Front 14

The slow Ca 2+ channels allow Na+ and Ca2+ through causing?

Back 14

prolonged depolarization (the plateau in AP)

Front 15

Where does the Ca 2+ come from in skeletal muscle?

Back 15

Intracellular SR

Front 16

Where does the Ca 2+ come from in cardiac muscle?

Back 16

slow Ca2+ channels

Front 17

What accounts for the longer AP and its plateau in cardiac muscles (as compared to skeletal)

Back 17

After AP, the permeability of the membrane for K+ decreases 5 fold (prevents K out)

Front 18

What is the velocity of conduction of the excitatory AP signal across atrial and ventricular muscle fibers?

Back 18

0.3-0.5 m/sec (1/10 the velocity in skeletal muscles)

Front 19

What is the velocity of conduction in Purkinje fibers?

Back 19

4 m/sec

Front 20

A period of time wehre a normal cardiac impulse cannot reexcite an already excited cardiac muscle?

Back 20

Refractory period

Front 21

What is the refractory period in the ventricles?

Back 21

0.25-0.30 second

Front 22

A periord of time where the muscle is more difficult to escite but nevertheless can be excited by a very strong excitatory signal

Back 22

Relative refractory period (.05 sec)

Front 23

How long is the refractory period for atria?

Back 23

0.15 sec

Front 24

What is excitation-contraction coupling?

Back 24

the AP causes the myofibrils of muscle to contract

Front 25

Describe how an AP enters the interiror of the cardiac muscle.

Back 25

T tubules- longitudinal sarcoplasmic tubules- SR releases Ca2+- sarcoplasm- myofibrils- muscle contraction

Front 26

How else does Ca 2+ get into the sarcoplasm?

Back 26

T tubules havve voltage dependant Ca 2+ channels (NOT in skeletal)

Front 27

What would happen without Ca 2+ from the T tubules?

Back 27

strenth of muscle contraction would be reduced

Front 28

Compare size of T tubules in skeletal and cardiac muscles.

Back 28

5 x as large in cardiac muscles and have mucopolysaccarides (-)

Front 29

Why does the strength of cardiac contraction depend on the amount of Ca 2+ in the ECM?

Back 29

openings of T tubules go directly into the ECM

Front 30

How does Ca 2+ get transported back into the SR after an AP?

Back 30

Ca2+-ATPase pump

Front 31

How else does Ca 2+ leave the cell?

Back 31

Ca 2+-Na+ exhanger, followed by Na+-K+ ATPase pump

Front 32

Events that occur from the beginning of one heartbeat to the beginning of the next?

Back 32

Cardiac cycle

Front 33

The atria contract 0.1 seconds before the ventricle, acting as

Back 33

a primer pump (20% increase in ventricular contraction)

Front 34

Relaxtion period where the heart fills with blood

Back 34

Diastole

Front 35

If the heart rate is 72 beats/min, what is the duration of the cardiac cycle?

Back 35

1/72 beats/min (.833 sec/beat)

Front 36

When a heartbear increases, which phase duration dcreases most?

Back 36

Diastole (relaxation)

Front 37

Spread of depolarization in the atrial?

Back 37

P wave

Front 38

P wave is followed by?

Back 38

Atrial contraction (slight increase in atrial pressure)

Front 39

Depolarization of the ventricles?

Back 39

QRS wave

Front 40

QRS wave is follwed by?

Back 40

Ventricular conraction and pressure increase and systole

Front 41

Atrial contraction causes

Back 41

a wave

Front 42

Pressure increase for the atria during contraction?

Back 42

Right- 4-6 mm Hg
Left- 7-8 mmHg

Front 43

Slight backflow from ventricles and bulging of the AV valve backwards causes

Back 43

c wave

Front 44

Slow flow of blood into the atria from the veins while the AV valves are closed causes?

Back 44

v wave

Front 45

When systole ends, the atria have been filling with blood (closed AV valves), diastole causes AV valves to open and blood to rush in

Back 45

Period of rapid filling of the ventricles

Front 46

Describe the three parts of diastole.

Back 46

1. rapid filling
2. blood passes directly thru atria from veins
3. contraction of atria

Front 47

Periord where the AV valves are closed, but the nevtricles are building up enough pressure to push semilunar valves open

Back 47

Isovolumic/Isometric contraction

Front 48

Once pressure exceeds 80 mm Hg in left ventricle (8 mm Hg) 70% of blood is immediately ejeected

Back 48

Period of rapid ejection

Front 49

Last 2/3 of emptying period, where the last 30% of blood is ejected

Back 49

Period of slow ejection

Front 50

Ventricular relation begins, decreasing the intraventricular pressures (.03-.06 sec)

Back 50

Isovolumic/Isometric relaxation

Front 51

The end diastolic volume in the ventricles

Back 51

110-120 mL

Front 52

Stroke volume in ventricles

Back 52

Emptying during systole (70mL)

Front 53

End systolic volume

Back 53

40-50 mL

Front 54

Ejection fraction

Back 54

end diatolic volume that is ejected (70/120)

Front 55

Prevent backflow during diastole

Back 55

Semilunar valves

Front 56

Prevent backflow during systole

Back 56

Tricuspid

Front 57

Pull vanes of valves inward toward ventricles to prevent their bulging too far backward into the aria

Back 57

Papillary muscles

Front 58

As compared to AV valves, semilunar valves

Back 58

1. snap to close (higher pressure)
2, velocity of ejection is greater

Front 59

What does the arterial pressure increase to after ventricular ejection?

Back 59

120 mm Hg

Front 60

Short period of backflow from the aorta into the left ventricle immediately before valve closer

Back 60

Incisura

Front 61

During diastole (before contraction), the aortic pressure is?

Back 61

80 mm Hg

Front 62

During systole (after ventricular contraction, the aortic pressure is?

Back 62

120 mm Hg

Front 63

First heart sound (low and long)

Back 63

Closure of AV valves

Front 64

Second heart sound (rapid snap, short)

Back 64

Closure of the semilunar valves

Front 65

The amount of E that the heart converts to work during each heartbeat

Back 65

Stroke work output

Front 66

Stroke work output x HR

Back 66

Minute work output

Front 67

Two forms of work output of the heart.

Back 67

1. volume-pressure work (external work) v. to a.
2. kinetic energy of blood flow (acc. blood to its ejection velocity)

Front 68

Mass of blood ejected x velocty of ejection sqared=

Back 68

kinetic energy of blood flow