Cardiac Muscle and Cardiac Output

Question 1

CONTRACTILE UNIT of myocardial cell

Z line to Z line

Answer 1

Sarcomere

Question 2

Maintain CELL TO CELL ADHESION

Answer 2

Intercalated Disks

Question 3

PRESENT at intercalated disks
LOW RESISTANCE OATHS b/w cells — RAPID electrical spread of AP
Electrical syncytium

Answer 3

Gap Junctions

Question 4

MORE NUMEROUS in cardiac muscles than in skeletal muscles

Answer 4

MITOCHONDRIA

Question 5

Carry AP into the cell interior
WELL DEVELOPED in VENTRICLES
Form DYADS w/ SR

Answer 5

T Tubules

Question 6

Small diameter tubules in close proximity to the contractile elements
STORAGE and RELEASE of calcium for EXCITATION-CONTRACTION coupling

Answer 6

Sarcoplasmic Reticulum

Question 7

End Diastolic Volume

Influenced by RIGHT ATRIAL PRESSURE

Answer 7

Preload

Inc Preload — Inc CO

Question 8

Equivalent to LEFT ventricle pressure — AORTIC PRESSURE

Equivalent to RIGHT ventricle pressure — PULMONARY ARTERY PRESSURE

Answer 8

Afterload

Question 9

INC venous return –> INC SV –> INC CO

Answer 9

Frank Starling Mechanism

inc VR – inc R atrial pressure – inc EDV (PRELOAD) — inc stretch of cardiac sarcomeres (in ventricular fiber length) – greater force of contraction (d.t. greater tension) – inc SV – inc CO

Question 10

INC venous return –> INC HR –> INC CO

Answer 10

Bainbridge Reflex

inc VR – inc R atrial pressure – (+) cardiopulmonary baroreceptors (low pressure receptors) – inc HR – inc CO

Question 11

EDV-ESV

70 mL

Answer 11

Stroke volume

Question 12

SV/EDV

55%

Answer 12

Ejection Fraction

Question 13

HR x SV

5 L/min (resting)

Answer 13

Cardiac Output

Question 14

VO2/AVO2

Answer 14

Cardiac Output (Fick Equation)