Cardiovascular 4

Question 1

ESV vs EDV

Answer 1

ESV: end systolic volume
EDV: end diastolic volume

Question 2

Pressure Volume Loop of Cardiac Cycle:
A-A’ Segment

Answer 2

Late Diastole
-starts at ESV (not all blood is pumped out after contraction)
-pressure in ventricle is lower than the atria and the AV valve opens causing the ventricle to passively fill with blood (80% is passive)

Question 3

Pressure Volume Loop of Cardiac Cycle:
A’-B Segment

Answer 3

Atrial Systole
-atria contracts -forces more blood into ventricle, slightly increasing volume and pressure
-at the end, maximal amount of blood is in ventricles
-this is EDV

Question 4

Pressure Volume Loop of Cardiac Cycle:
B-C Segment

Answer 4

Isovolumetric Contraction
-ventricle begins contracting -closes AV valve
-continued contraction causes a large increase in pressure within the ventricle

Question 5

Pressure Volume Loop of Cardiac Cycle:
C-D Segment

Answer 5

Ventricular Ejection
-once pressure in ventricle rises above 80mmHg, exceeds the aorta
-aortic valve opens causing rapid ejection of blood
-pressure still rises as ventricle contracts
-part way through this segment the ventricle begins to relax and pressure begins to drop, but blood still flows in due to inertia

Question 6

Pressure Volume Loop of Cardiac Cycle:
DA Segment

Answer 6

Isovolumetric Relaxation
-pressure in aorta begins to exceed ventricle
-causes semi lunar valve to close, ventricle continues to relax

Question 7

Left Venticle Systemic circuit ranges mmHg from:

Answer 7

About 10mmHg in pressure to 120mmHg
-about 50-125mL

Question 8

Right Ventricle Pulmonary Circuit mmHg ranges:

Answer 8

Around 15-35mmHg
-about 60-140mL

Question 9

EDV

Answer 9

End Diastolic Volume -the maximal volume in the ventricle after ventricular filling
70kg man at rest is around 135mL

Question 10

ESV

Answer 10

End Systolic Volume -the minimal amount of blood in the ventricles, blood left after ventricular contraction
-around 65mL for 70kg male

-provides safety margin, a more forceful contraction will cause larger SV, causing decrease in ESV

Question 11

SV

Answer 11

Stroke Volume -the amount of blood ejected during a single ventricular contraction
-around 70mL in 70kg male

-can increase to as high as 100mL and is modulated by autonomic system, venous return, and certain drugs

Question 12

SV=

Answer 12

EDV-ESV
Ex) 135mL- 65mL
=70mL

Question 13

EF

Answer 13

Ejection Fraction -the percentage of EDV that is ejected fro the heart (SV)
=SV/ EDV
Ex) 70mL/ 135mL
=52%

Question 14

CO

Answer 14

Cardiac Output
Heart rate x Stroke volume
-flow of blood delivered from one ventricle per minute
-about 4-5 L/min
-pulmonary and systemic outputs are usually identical
-can raise to 30-35 L/min during exercise

Question 15

Cardiac output can be modified by adjusting

Answer 15

Heart rate or stroke volume

Question 16

2 Factors that determine the amount of force generated by cardiac muscle:

Answer 16

Contractility of the heart and
Length of muscle fibers at the beginning of contraction

Question 17

How does contractility affect the amount of force generated by cardiac muscle

Answer 17

The intrinsic ability of cardiac muscle fibres to contract at any given fiber length and is a function of Ca2+ entering and interacting with the contractile filaments

Question 18

How does the length of the muscle fibres at the beginning of contraction affect the amount of force generated by cardiac muscle

Answer 18

This is determined by the volume of blood in the ventricle at the beginnning of contraction (EDV)

Question 19

Inotropic agent

Answer 19

Any chemical that affects contractility
-influenced by an inotropic effect

Question 20

Ionotropic effect

Answer 20

The influence to an inotropic agent

Question 21

How does contractility increase in cardiac muscle

Answer 21

Catecholamines (NE and E) released from sympa neurons or adrenal medulla
-cause a positive inotropic effect regardless of EDV
-increases as the amount of Ca2+ available for contraction INCREASES

Question 22

Chemicals increasing contractility have a what effect

Answer 22

A positive ionotropic effect

Question 23

Chemicals decreasing contractility have a what effect

Answer 23

A negative inotropic effect