Cardiovascular Exam I - Physiology

Front 1

Heart beat is caused by what current?

How does this current work?

Back 1

Resting Na current that can occur between - 70 and -40 mV

Na channels open spontaneously and slowly depolarize pacemaker cell resting potential until it reaches threshold

Front 2

These channels open at threshold and create action potential

Back 2

Voltage gated Ca channels

Front 3

_ returns membrane to resting potential

Back 3

Slower opening of slower voltage gated K channels

Front 4

"resets" (inactivates) Na channels

Back 4

Hyperpolarization

Front 5

What is a typical non-pacemaker cell potential

Back 5

-90--> -110

Front 6

Damage (e.g MI) that depolarizes non-pacemaker cells can activate Na channels and cause these cells to act as pacemaker cells - this is called _

Back 6

ABNORMAL AUTOMATICITY

Front 7

Increase the rate of opening of funny channel (Na channel)

Back 7

Cyclic nucleotides

Front 8

Increased opening of Na channels increases heart rate - this is effect of which agonists>

Back 8

Dopamine/adrenergic

Front 9

Decreased channel opening decreases heart rate - this is the effect of which agonists

Back 9

Muscarinic

Front 10

What happens when Purkinje cells are depolarized (as in hypoxia)

Back 10

Many Na channels move from resting to closed state, where they cannot be activated. Further depolarization of these cells can activate " funny Na channels" and cause them to act like pacemaker cells

Front 11

Creates NORMAL SINUS RHYTHM

Back 11

SA node

Front 12

Creates NODAL RHYTHM if SA node fails

Back 12

AV node

Front 13

Causes P and QRS waves

Back 13

Na entry

Front 14

Ca enters atria and ventricles during _

Back 14

PR and ST segments

Front 15

Exits in the T wave

Back 15

K

Front 16

T wave height is proportional to _

Back 16

Plasma K

Front 17

This condition can invert T wave

Back 17

Hypokalemia

Front 18

This ion blocks Ca channel

Back 18

Mg

Front 19

Ca and Na depolarize during which phases

Back 19

0,1,2

Front 20

Repolarization occurs when Ca current ceases while K current persists - which phase

Back 20

3

Front 21

Factors that decrease K currents increase or decrease AP duration?

Back 21

Increase

Front 22

These cells are most susceptible to increased AP duration

Back 22

Midwall cells ( M cells)

Front 23

This condition can cause EAD's if the cardiac AP exceeds effective refractory period

Back 23

Long Q-T syndrome

Front 24

Describe conditions that can cause long Q-T syndrome

Back 24

- Unintended side effect of drugs that inhibit K channels (sotalol) or with congenital K channels defects
- Can also occur in bradycardia due to decreased lusitropic state

Front 25

Tosade de Pointes is usually preceded by _

Back 25

Several periods of EAD's

Front 26

These are thought to cause Tosade de Pointes

Back 26

EAD's + dispersion of repolarization

Front 27

What is often given for Tosade de Pointes and why

Back 27

Mg - blocks Ca channels and since K channels are already open, the cell repolarizes earlier

Front 28

Thought to cause Premature Ventricular Contractions (PVC)

Back 28

DAD- Delayed After Depolarizations

Front 29

What comes first EKG or mechanical events

Back 29

EKG events PRECEDE mechanical events

Front 30

Systole starts with _

Ends with _

Back 30

Ventricular contraction and closure of AV valve

Closure of semilunar valve

Front 31

Ventricular relaxation extending from semilunar valve closure to ventricular contraction and AV valve closure

Back 31

Diastole

Front 32

4 phases of systole in cardiac cycle

Back 32

1. Isovolumic contraction-no change in LV blood volume (end diastolic volume)
2.Rapid ejection-aortic valve opens followed by rapid ejection of blood from LV into aorta.
3. Reduced ejection-slowing of blood from ventricle to aorta
4. Aortic valve closure(incisura or dicrotic notch-rebound of blood back into closed Aortic valve cusps

Front 33

Brief period just prior to aortic valve closure (actually part of systole)
Ventricles are relaxing with semilunar valves still open; reversal of flow in aorta

Back 33

Protodiastole

Front 34

3 parts of ventricular filling

Back 34

1.Rapid filling-early rapid filling from atria
2.Reduced filling (Diastasis)-slowing of filling as pressures equalize
3.Atrial Systole-atrial contraction (“Atrial kick”)

Front 35

a wave is due to _

Back 35

atrial contraction

Front 36

c wave is due to _

Back 36

ventricular contraction (bulging of AV valves back into atria)

Front 37

v wave is due to _

Back 37

venous return (pulmonary blood flow into atria with AV valves closed)

Front 38

Fall in atrial pressure following the c-wave. Base of ventricle pulls away from atria during contraction creating fall in pressure.

Back 38

X descent = systolic collapse

Front 39

Fall in atrial pressure following the v-wave- rapid outflow of blood from atria to ventricles causing pressure drop.

Back 39

Y descent = diastolic collapse

Front 40

Major contributor to “afterload”, the resistance the left ventricle has to pump against to eject blood

Back 40

Aortic pressure

Front 41

1st heart sound starts with _ and extends to _

Back 41

Closure of AV valves to the opening of semilunar valve

Front 42

2nd heart sound is associated with _

Back 42

Semilunar valve closure