Heart Quiz 2

Question 1

Operation of Semilunar Valves

Answer 1

Open when pressure generated in ventricle is greater than circulation
Close when pressure generated in ventricle is less than circulation

Question 2

Coronary Circulation

Answer 2

Blood vessels of the heart will carry blood to the cardiac muscle

Question 3

1st Branches of the Aorta

Answer 3

Left Coronary Artery and Right Coronary Artery

Question 4

Left Coronary Artery

Answer 4

1. Anterior Interventricular Artery: supplies interventricular septum and anterior walls of ventricles
2. Circumflex Artery: passes around the left side of the heart, supplies left atrium and posterior wall of the left ventricle

Question 5

Right Coronary Artery

Answer 5

Supplies right atrium

1. Marginal Artery: supplies lateral right atrium and ventricle
2. Posterior Interventricular Artery: supplies posterior walls of the ventricles

Question 6

Structure of Cardiac Muscle

Answer 6

Made up of cardiocytes
Interconnected by intercalated disks
Larger T-Tubules than skeletal tissue that release Ca2+
Not prone to fatigue
Uses fatty acids as a fuel source, glucose at rest

Question 7

Intercalated Disks

Answer 7

Join all cardiac cells

Question 8

3 Features of Intercalated Disks

Answer 8

1. Interdigitating Folds: cells interlock with each other and increase surface area
2. Mechanical Junctions: fascia adherens and desmosomes
3. Electrical Junctions: gap junctions that allow ions to flow from cytoplasm to cardiocytes

Question 9

Fascia Adherens

Answer 9

Most abundant

Question 10

Desmosomes

Answer 10

Prevent cardiocytes from pulling apart

Question 11

Similarities Between Myocardial Cells and Skeletal Muscle Fibers

Answer 11

Striated
Z-Discs
Use tropomyosin and troponin to contract

Question 12

Differences Between Myocardial Cells and Skeletal Muscle Fibers

Answer 12

Skeletal: voluntary contraction, excitation coupling
Cardiac: involuntary contraction, SA node and gap junctions

Question 13

Pacemaker Physiology

Answer 13

1. Slow leak Na2+ enters the cell
2. Voltage gated Ca2+ channels open (at -40mV)
3. K+ channels open (at 0mV)
4. Repeat once polarization is complete

Question 14

Action Potential of Ventricular Cardiocyte

Answer 14

1. Voltage-gated Na+ channels open
2. Na+ depolarizes the membrane and opens more Na+ channels, creating a positive feedback cycle and rising membrane voltage
3. Na+ channels close when cell depolarizes, voltage peaks at +30mV
4. Ca2+ slowly enters and prolongs depolarization, causing a plateau
5. Ca2+ channels close and Ca2+ is transported out of the cell; K+ channels open, and outflow returns membrane to resting potential

Question 15

Conduction System of the Heart

Answer 15

1. SA node fires
2. Excitation spreads through atrial myocardium
3. AV node fires
4. Excitation spreads down AV bundle
5. Purkinje fibers distribute excitation through ventricular myocardium

Question 16

Electrical Activity of Myocardium

Answer 16

1. Atria begin to depolarize (P wave)
2. Depolarization is complete
3. Ventricular depolarization begins at apex and moves superiorly while atrial repolarization occurs (QR waves)
4. Ventricular depolarization is complete (S wave)
5. Ventricular repolarization occurs at apex (T wave)
6. Ventricular repolarization complete, heart ready for next cycle

Question 17

Ventricular Fibrillation

Answer 17

Most serious disturbance
Heart cannot pump blood
Irregular waves of depolarization
Chambers contract in rapid, unsynchronized ways

Question 18

Atrial Fibrillation

Answer 18

Atria quiver and prevents blood from entering ventricles

Most common in elderly

Question 19

Heart Block

Answer 19

Conduction passes weakly from the atria through AV bundle
Damage to AV node causes total heart block
Ventricles beat at intrinsic rates

Question 20

Premature Ventricular Contraction

Answer 20

Ectopic focus firing and setting off an extra beat before the normal signal
QRS is inverted
Common in college students
Caused by stress, sleep deprivation, caffeine