Chapter 20 - The Heart - The Cardiac Cycle

Question 1

What are the 2 phases of the cardiac cycle

Answer 1

systole
diastole

Question 2

What is happening during diastole

Answer 2

When the heart muscles are RELAXED and fill with blood

Question 3

What is happening during systole

Answer 3

a CONTRACTION pumps blood out of the heart

Question 4

In which phase are the semilunar valves open?

Answer 4

systole

Question 5

What is the FIRST STEP of the cardiac cycle

Answer 5

atrial systole
atrial contraction forces blood into the ventricles

Question 6

What happens after atrial systole?

Answer 6

atrial diastole
(atria relax)

Question 7

What happens after atrial diastol?

Answer 7

1st phase of ventricular systole
(ventricular contraction pushes the AV valves closed but does not create enough pressure to open the semilunar valves

Question 8

what happens after the 1st phase of ventricular systole?

Answer 8

2nd phase of ventricular systole
(ventricular pressure rises and exceeds pressure in the arteries. SEMILUNAR VALVES OPEN AND BLOOD IS EJECTED)

Question 9

What happens after the 2nd phase of ventricular systole?

Answer 9

ventricular diastole (early)
semilunar valves close and blood flows into the relaxed atria

Question 10

what happens in ventricular diastole (late)

Answer 10

all chambers are relaxed and the ventricles fill passively

Question 11

in which phase is blood from the atria ejected into the ventricles

Answer 11

when the atria contract (systole)

Question 12

what is the “stroke volume” (SV)

Answer 12

the volume of blood ejected per beat (each ventricular ejects 70-80mL of blood)

Question 13

what is the “end diastolic volume”

Answer 13

the maximum amount of blood that each ventricle will hold in this cycle

Question 14

what does it mean when the ventricles are in “isovolumetric contraction”

Answer 14

the first phase of ventricular systole

ventricular pressures are not yet high enough to open the semilunar valves and force blood out, but tension and pressures are rising

ISOMETRIC CONTRACTIONS ARE OCCURRING

Question 15

in ventricular ejection, what term can you use to describe their ejection

Answer 15

isotonic. the muscle cells shorten and tension production remains constant

Question 16

What is the ESV?

Answer 16

END SYSTOLIC VOLUME

Question 17

explain what end systolic volume means

Answer 17

the amount of blood remaining in a ventricle after the semilunar valve closes

Question 18

when ventricular pressures fall below those of the atria, what happens?

Answer 18

the atrial pressures force the AV valves ope

Question 19

what is “isovolumetric relaxation”

Answer 19

occurs during ventricular diastole
all the heart valves are closed. ventricular pressure drops rapidly over this period because of the elasticity of the connective tissues of the heart and cardiac skeleton helps “re expand” the ventricles to their resting dimensions

Question 20

when the heart rate increases, all the phases of the cardiac cycle are,,,

Answer 20

shortened

Question 21

what is the term for “listening to the heart”

Answer 21

auscultation

Question 22

what is used to listen to heart sounds

Answer 22

a stethoscope

Question 23

do the 2 ventricles eject equal volumes of blood?

Answer 23

yes

Question 24

what does EDV stand for and what does it mean

Answer 24

end diastolic volume

the amount of blood in each ventricle at the end of ventricular diastole (the start of ventricular systole)

Question 25

what does ESV stand for and what does it mean

Answer 25

end systolic volume the amount of blood remaining in each ventricle at the end of ventricular systole

Question 26

What does SV stand for and what does it mean

Answer 26

stroke volume the amount of blood pumped out of each ventricle during a single beat

Question 27

how can the stroke volume (SV) be calculated?

Answer 27

SV= EDV-ESV

Question 28

what is the "ejection fraction"

Answer 28

the percentage of the EDV represented by the SV

Question 29

what is the most important factor in an examination of a single cardiac cycle?

Answer 29

stroke volume

Question 30

what does CO stand for and what does it mean

Answer 30

cardiac output the amount of blood pumped by the left ventricle in one minute

Question 31

CO=

Answer 31

SV * HR

Question 32

NAME 2 FACTORS AFFECTING HEART RATE

Answer 32

autonomic innervation(parasympathetic decreases heart rate) hormones (epinephrine, norepenephrine, thyroid hormone all increase heart rate)

Question 33

name 2 factors affecting stroke volume

Answer 33

EDV ESV

Question 34

What is the "autonomic headquarters" for cardiac control?

Answer 34

the cardiac centers of the medulla oblongata

Question 35

acetylcholine ____ heart rate

Answer 35

decreases

Question 36

acetylcholine is released by ___ neurons

Answer 36

parasympathetic

Question 37

"filling time" is the duration of the......

Answer 37

ventricular diastole

Question 38

what is the "venous return"

Answer 38

the amount of blood returning to the heart through the veins

Question 39

what ADJUSTS the heart rate in response to the venous return

Answer 39

the atrial reflex

Question 39

what ADJUSTS the heart rate in response to the venous return

Answer 39

the atrial reflex

Question 40

what ADJUSTS the heart rate in response to the venous return

Answer 40

the atrial reflex

Question 41

filling time depends entirely on.....

Answer 41

the heart rate

Question 42

what is the preload?

Answer 42

the degree of stretching in ventricular muscle cells during ventriculr diastole

Question 43

what is the "afterload"

Answer 43

the amount of tension that the contracting ventricle must produce to force open the semilunar valve to eject blood

Question 44

the greater the EDV, the ____ the preload

Answer 44

larger

Question 45

what is the term for the amount of force produced by a singular contraction?

Answer 45

contractility

Question 46

what is the cardiac reserve?

Answer 46

the difference between resting and maximal output