CV IV

Question 1

Late diastole

Answer 1

Starts with atria relaxed and fills from veins
Both sets of chambers are relaxed and ventricles fill passively
Pressure in atria starts to exceed ventricle
AV valves open Passive filling 80%

Question 2

Atrial systole

Answer 2

Atrial contraction forces small amount of additional blood
20% of ventricular filling due to atrial contraction

Question 3

Lub

Answer 3

First heart sounds
Shutting of AV valves as ventricular blood tries to go back to atria
Sound is vibrations of wall as blood hits valve

Question 4

Isovolumetric ventricular contraction

Answer 4

No change in volume
Pushes AV valves closed but doesn’t create enough pressure to open semilunar valves
Both valves closed and pressure builds

Question 5

Ventricular ejection

Answer 5

Ventricle pressure rises exceeds pressure in arteries (aorta or pulmonary), semilunar valves open

Question 6

Dub

Answer 6

Second heart sound
Closure of semilunar valves

Question 7

Isovolumetric ventricular relaxation

Answer 7

Pressure in ventricles falls,blood flows back into cusps of semilunar valves and snaps them closed

Question 8

What is the pressure volume loop

Answer 8

Another way to look at cardiac cycle of systemic

Question 9

ESV

Answer 9

Blood left in ventricle after ventricular contraction, minimum amount
Safety reservoir
~65ml

Question 10

EDV

Answer 10

Amount of blood in ventricle at end of diastole, after ventricular filling
Max volume
~135ml

Question 11

A-A’

Answer 11

Late diastole
- starts at ESV
Big change volume because ventricle relaxing, no change in pressure

Question 12

A’-B segment

Answer 12

Atrial systole
Slight increase in volume and blood
End diastolic volume

Question 13

B-C segment

Answer 13

Isovolumetric contraction
Large increase in pressure

Question 14

C-D segment

Answer 14

Ventricular ejection
- pressure rises
- pressure drops as ventricles relax but blood still flows

Question 15

C-D segment is

Answer 15

Stroke volume

Question 16

D-A segment

Answer 16

Isovolumetric relaxation
- pressure drops, no volume change

Question 17

Pressure volume loop for RV

Answer 17

Short low pressure circuit
- ejects same amount of blood as systemic
- overall stroke volume same
- needs less pressure
- lower resistance (short, large diameter)

Question 18

Wiggers diagram

Answer 18

Diagram has left ventricular volume, left and aortic pressures, ECG

Question 19

D

Answer 19

Late diastole

Question 20

C

Answer 20

Start of isovolumetric contraction

Question 21

E

Answer 21

End diastolic pressure

Question 22

A

Answer 22

Ventricle exceeds pressure in aorta

Question 23

E to F

Answer 23

Ventricular ejection

Question 24

B

Answer 24

Pressure in aorta starts to exceed ventricle, semilunar shuts

Question 25

Stroke volume

Answer 25

Amount of blood ejected during a single ventricular contraction ~70ml

Question 26

What is SV equation

Answer 26

EDV-ESV

Question 27

What is ESV for

Answer 27

Provides safety margin, more forceful contraction will cause larger stroke

Question 28

What is stroke volume modulated by

Answer 28

ANS, venous return, certain drugs

Question 29

Ejection fraction

Answer 29

Percentage of EDV that is ejected from heart

Question 30

Ejection fraction equation

Answer 30

SV/EDV

Question 31

Cardiac output

Answer 31

Heart rate x stroke volume Flow of blood delivered from one ventricle in a given time period (usually a minute) Measure of cardiac performance

Question 32

What happens when cardiac outputs of the pulmonary and systemic circuit are not identical

Answer 32

Blood pools in circuit feeding the weaker side

Question 33

How much does CO rise during exercise

Answer 33

30-35L/min

Question 34

Steve has EDV of 150ml, an ESV of 30ml and HR of 90bpm. What’s Steve’s CO

Answer 34

SV X HR (EDV -ESV) X HR (150 ml/b - 30ml/b) x 90 b/m =10800 ml/min 10.8 L/min

Question 35

How is cardiac output modified

Answer 35

1. By adjusting HR By parasympathetic or sympathetic 2. Adjusting stroke volume

Question 36

What is SV directly related to

Answer 36

To force generated by cardiac muscle during contraction As force of contraction increases, SV increases

Question 37

What are 2 factors that determine amount of force generated by cardiac muscle

Answer 37

1. Contractility of heart 2. Length of muscle fibres at beginning of contraction

Question 38

What is contractility of heart

Answer 38

Intrinsic ability of cardiac muscle to contract at any given fibre length and is function of Ca entering and interacting with contractile filaments

Question 39

What is length of muscle fibres determined by

Answer 39

Volume of blood in ventricle at beginning of contraction (EDV)

Question 40

What is contractility controlled by

Answer 40

Nervous and endocrine systems

Question 41

Inotropic agent

Answer 41

Any chemical that affects contractility

Question 42

Inotropic effect

Answer 42

Influence of Inotropic agent

Question 43

Positive inotropic effect Negative inotropic effect

Answer 43

Chemicals increasing contractility Chemicals decreasing contractility

Question 44

What causes positive inotropic effect

Answer 44

Norepinephrine, epinephrine Sympathetic modulation