The Heart 2

Question 1

What two junctions are found at intercalated disks?

Answer 1

Gap, Desmosomes

Question 2

What is the resting potential, amplitude, and peak value of a ventricular action potential. How long does a ventricular AP last?

Answer 2

R: -90mV
A: 125 mV
P: 30mV
D: 0.3 seconds

Question 3

P - Wave
PR - Segment
QRS Complex
ST- Segment
T - Wave

Answer 3

P: Atrial Depolarization (upstoke of AP across atrium)
PR: Atrium is Depolarized, SA –> AV signal
QRS: Ventricle Depolarization, Atrial Re-Polarization (Upstroke spread across ventricles)
ST: Ventricle is Uniformly Depolarized
T: Ventricle Re-Polarization

Question 4

Name the Two Atrioventricular, Semilunar Valves

Answer 4

A: Tricuspid (right), Mitral (left)
S: Pulmonary Valve, Aortic Valve

Question 5

What event causes 1st and 2nd heart sounds

Answer 5

1: atrioventricular valves closing
2: semilunar valves closing

Question 6

When does isovolumetric contraction, and relaxation occur?

Answer 6

at the beginning and end of Ventricular Systole

Question 7

Normal Atrial Range __________ mmHg
Left Ventricular Systolic, Diastolic ___, ____ mmHg
Aortic during Systole, Diastole ___, ___ mmHg

Answer 7

At: 10 - 15 mmHg
LV: S - 120+, D - 0 mmHg
AO: S - 120, D - 80 mmHg

Question 8

What is the End Diastolic Volume (EVD), Ends Systolic Volume (ESV)?

Answer 8

ED: 135mL
ES: 65 mL

Question 9

Resting Potential For Cells in the Atrial/ Ventricle? Sinoatrial node?

Answer 9

A/V: -90 mL

SAN: variable (pacemaker activity - Remember GRAPH) hits threshold Faster - initiates AP throughout heart

Question 10

Digitalis Inhibits what function of Myocardiac cells

Answer 10

Na+ / K+ (atpase)

Question 11

What happens when Na+ / K+ (atpase), Na+ / Ca++ pumps are inhibited?

Answer 11

the membrane potential goes to 0 mV.

Question 12

What is a bundle of Kent? what does it lead to?

Answer 12

BOK is an additional electrical pathway from the atrium to ventricles, can cause cardiac arrhythmias.

Question 13

Name the two types of cardiac action potential.

Answer 13

Fast Response (Myocyte cells of ventricle, atrium, PK fibers)

Slow Response (Pacemaker cells of the SA, AV nodes)

Question 14

Explain Slow Action Potentials

Answer 14

1. Sodium channels causes slight upstoke
2. Calcium T - continues Depolarization to Threshold.
3. Calcium L (O/C) Depolarization (upstoke)
4. K (k- slow) (O) - Re-Polarization
5. Na+ (O) - Activated by re-polarization

Question 15

Explain Fast Action Potentials

Answer 15

1. Sodium channels causes Upstoke
2. K (O) - Slight Re-Polarization
3. Calcium L (O) - Resist Re-Polarization (plateau)
4. Calcium L (C)- Re-Polarization Continues
5. K (O) - Hyper-Polarization
6. K (C) - Normalization (re-polarized)
7. **Need new stimulus

Question 16

Electrical Pathway

Answer 16

SAN –> ATRIUM myocytes –> AVN –> PR —> VENTRICLE myocytes

Question 17

What is Stroke Volume

Answer 17

EDV - ESV = amount of blood leaving heart

Question 18

Define Cardiac Output

Answer 18

SV (mL/beat) * HR (beats/min)

Question 19

Isovolumetric Contraction (Explain in detail)

Answer 19

Pressure in Aorta > Ventricular pressure > atrium pressure

Both Valves are closed

Question 20

PQRST -
Y, X- Axis’ -
Why so small mV reading ? -

Answer 20

Alphabetical
1mm cubes = 1/10 mV , time (hr determination)
Through skin

Question 21

Define Stenosis

Define Ischemia

Answer 21

i: restricted O2 supply
s: narrowing

Question 22

Define Myocardial Infarction

Answer 22

The process of cells dying due to an embolism (stenosis plaque) completely blocking blood flow to myocardium