Circulatory System - Heart and Vessels

Question 1

What does sympathetic (action) nerves do to heart rate?

Answer 1

increase heart rate and contraction strength

Question 2

The Conduction System order

Answer 2

-Sinoatrial (SA) node: modified cardiomyocytes
-Signals spread throughout atria
-Atrioventricular (AV) node
-Atrioventricular (AV) bundle (bundle of His)
-Subendothelial conducting networks

Question 3

What does parasympathetic (calming) nerves do to heart rate?

Answer 3

slow heart rate

Question 4

Systole

Answer 4

contraction - action of the ventricles

Question 5

Diastole

Answer 5

relaxation - action of the ventricles

Question 6

Blood pressure is read by

Answer 6

systolic over diastolic

Question 7

Sinus Rhythm

Answer 7

normal heartbeat triggered by the SA node
-adult at rest is typically 70 to 80 bpm

Question 8

Ectopic Focus

Answer 8

a region of spontaneous firing other than the SA node

Question 9

Cardiomyocytes action potential phases

Answer 9

-depolarization
-plateau phase lasts 200 to 250ms, sustains contraction for expulsion of blood from heart
-repolarization phase

Question 10

Cardiomyocytes have a stable resting potential of

Answer 10

-90, depolarize only when stimulated

Question 11

P wave

Answer 11

-SA node fires, atria depolarize and contract
-Atrial systole begins 100ms after SA signal

Question 12

QRS complex

Answer 12

-ventricular depolarization
-complex shape of spike due to different thickness and shape of the two ventricles

Question 13

ST segment

Answer 13

-ventricular systole
-corresponds to plateau in myocardial action potential

Question 14

T wave

Answer 14

-ventricular repolarization and relaxation

Question 15

Deviations of ECG from normal can indicate:

Answer 15

-myocardial infarction (MI)
-abnormalities in conduction pathways
-heart enlargement
-electrolyte and hormone imbalances

Question 16

Events occurring on left side of the heart

Answer 16

-when ventricle relaxes and expands, its internal pressure falls
-if mitral valve is open, blood flows into left ventricle
-when ventricle contracts, internal pressure rises
-AV valve close, the aortic valve is pushed open and blood flows into aorta from left ventricle

Question 17

First heart sound (S1)

Answer 17

“lubb” - closure of AV valves

Question 18

Second heart sound (S2)

Answer 18

“dupp” - closure of semilunar valves

Question 19

All phases of cardiac cycle

Answer 19

-ventricular filling (during diastole)
-isovolumetric contraction (during systole)
-ventricular ejection (during systole)
-isovolumetric relaxation (during diastole)

Question 20

Ventricular Filling

Answer 20

-ventricles expand and their pressure drops below that of the atria
-AV valve open and blood flows into the ventricles
-end-diastolic volume achieved in each ventricle

Question 21

Isovolumetric Contraction

Answer 21

-atria repolarize, relax and remain in diastole for rest of cardiac cycle
-ventricles depolarize, causing QRS complex, and begin to contract
-AV valves close as ventricular blood surges back against the cusps
-Heart sound S1 occurs at the beginning of this phase
-“isovolumetric” because although ventricles contract, they do not eject blood
-cardiomyocytes exert force, but with all four valves closed, the blood cannot go anywhere

Question 22

Ventricular Ejection

Answer 22

-begins when ventricular pressure exceeds arterial pressure and semilunar valves open
-pressure peaks in left ventricle at about 120-25mm Hg in the right
-ejection lasts about 200-250 corresponds to plateau phase of cardiac action potential
-T wave of ECG occurs late in this phase
-Stroke volume (SV) is about 70mL

Question 23

Isovolumetric Relaxation

Answer 23

-T wave ends and ventricles begin to expand
-Blood from aorta and pulmonary trunk briefly flows backward filling cusps and closing semilunar valves
-“isovolumetric” because semilunar valves are closed and AV valves have not yet opened
-when AV valves open, ventricular filling begins again

Question 24

Wiggers Diagram

Answer 24

1a-rapid filling
1b-diastasis
1c-atrial systole
2-isovolumetric contraction
3-ventricular ejection
4-isovolumetric relaxation

Question 25

Cardiac output

Answer 25

heart rate x stroke volume

Question 26

Cardiac reserve

Answer 26

the difference between a person’s maximum and resting CO
-increases with fitness, decreases with disease

Question 27

Tachycardia

Answer 27

resting adult heart rate about 100 bpm

Question 28

Bradycardia

Answer 28

resting adult heart rate of less than 60 bpm

Question 29

Three variables govern stroke volume

Answer 29

-preload
-contractility
-afterload

Question 30

Angina pectoris

Answer 30

chest pain from partial obstruction of coronary blood flow
-pain is caused by ischemia of cardiac muscle
-obstruction partially blocks blood flow
-myocardium shifts to anaerobic fermentation, producing lactate and this stimulating pain

Question 31

Myocardial Infarction (MI)

Answer 31

sudden death of a patch of myocardium resulting from long-term obstruction of coronary circulation
-atheroma
-cardiac muscle downstream of the blockage dies
-some painless heart attacks may disrupt electrical conduction pathways, leading to fibrillation and cardiac arrest
-MI responsible for about 27% of all deaths in the US

Question 32

Valvular Insufficiency (incompetence)

Answer 32

any failure of a valve to prevent reflux (regurgitation), the backward flow of blood

Question 33

Mitral Valve Prolapse

Answer 33

insufficiency in which one or both mitral valve cusps bulge into atria during ventricular contraction

Question 34

Coronary Artery Disease (CAD)

Answer 34

a constriction of the coronary arteries