The Heart

Question 1

what is the function of chordae tendineae?

Answer 1

stabilize the cusps during ventricular contractions and hold the cusps in place preventing retrograde flow of blood

Question 2

what is the serous pericardium?

Answer 2

combination of visceral and parietal pericardium

Question 3

SV = ______

Answer 3

EDV - ESV

Question 4

what is EDV?

Answer 4

end diastolic volume. Volume in ventricles and atria at the end of diastole.

Question 5

what does EDV represent?

Answer 5

maximal volume of the chambers of the heart (just before the aortic and pulmonary valves open)

Question 6

what does ESV represent?

Answer 6

minimum amount of blood in chambers of the heart

Question 7

Does the heart completely empty?

Answer 7

NO

Question 8

define Stroke Volume (SV)

Answer 8

amount of blood pumped from ventricle per beat

Question 9

T/F: the R/L atria are induced to contract simultaneously?

Answer 9

TRUE

Question 10

What is the pathway for electrical activity in the heart?

Answer 10

1. SA node
2. AV node
3. bundle of His
4. Purkinje fibers

Question 11

why is there a delay at the AV node?

Answer 11

allows maximal filling and contraction

Question 12

what does a P wave represent on a ECG?

Answer 12

depolarization of atria in response to SA node triggering

Question 13

what does the PR interval represent?

Answer 13

delay of AV nodes to allow filling of ventricles

Question 14

what does the QRS complex represent?

Answer 14

depolarization of ventricles, triggers main pumping contractions

Question 15

What does the ST segment represent?

Answer 15

beginning of ventricle repolarization, should be flat

Question 16

What does the T wave represent?

Answer 16

ventricular repolarization

Question 17

T/F: the heart has a refractory period?

Answer 17

TRUE

Question 18

define CO

Answer 18

liters of blood pumped per minute

Question 19

CO = _______

Answer 19

SV * HR

Question 20

define preload

Answer 20

volume of blood coming back to heart

Question 21

what occurs if preload is compromised?

Answer 21

1. SV to R ventricle is compromised
2. amt of blood going to lungs is compromised
3. blood going to left side of heart is compromised
4. CO to rest of body is decreased

Question 22

SV is regulated by what 3 variables?

Answer 22

1. preload (EDV)
2. afterload (TPR)
3. contractility

Question 23

what is TPR?

Answer 23

total peripheral resistance

Question 24

define afterload

Answer 24

resistance left ventricle must overcome to circulate blood (systolic BP)

Question 25

what happens if afterload is compromised?

Answer 25

the heart has to work harder

Question 26

relationship between afterload and SV, CO?

Answer 26

increase in afterload = decrease in SV and CO

Question 27

What is the Frank Starling Law?

Answer 27

increased EDV stretches cardiac muscle causing an increase in contractility and thus increasing SV

Question 28

what does the Frank Starling Law demonstrate?

Answer 28

the role that preload has in defining the SV

Question 29

what is contractility?

Answer 29

strength of a contraction. It is a measure of pump function

Question 30

how is contractility assessed?

Answer 30

EF (ejection fraction)

Question 31

what does EF tell us?

Answer 31

provides insight into delivery of blood to systemic circulation, assess cardiac contractility

Question 32

EF = __________

Answer 32

(SV/EDV) * 100

Question 33

what is a normal EF?

Answer 33

~50-75%

Question 34

what does venous return influence?

Answer 34

EDV

Question 35

what factors influence venous return?

Answer 35

1. blood volume 2. breathing (neg. intrathoracic pressure) 3. venous pressure

Question 36

what is the inherent rate of the SA node (in total absence of neural or hormonal input)?

Answer 36

100 bpm

Question 37

T/F: Cardiac muscles contract all or nothing?

Answer 37

False, cardiac muscle can have graded contractions dependent on the amount of Calcium being released by the SR

Question 38

T/F: cardiac muscle can grade the strength of their contractions?

Answer 38

TRUE

Question 39

difference between refractory periods in cardiac and skeletal muscle?

Answer 39

skeletal muscle has a shorter refractory period which means contractions can add up and result in tetanus. The heart has a longer absolute refractory period

Question 40

what is the period called between the aortic valve closing and the AV valve opening?

Answer 40

isovolumetric ventricular relaxation

Question 41

when does isovolumetric ventricular relaxation occur?

Answer 41

during diastole, prior to the AV valves opening and after the aortic/pulmonary valves close

Question 42

when does atrial contraction occur?

Answer 42

at the end of diastole, after most of the ventricular filling has taken place

Question 43

at rest the SA node is more heavily influenced by ________

Answer 43

parasympathetic vagus input

Question 44

what are the 3 factors that influence changes in SV?

Answer 44

1. changes in EDV >> preload 2. changes in sympathetic input 3. afterload

Question 45

SV is directly proportional to _____

Answer 45

EDV

Question 46

the relationship between SV and EDV is known as ________

Answer 46

the Frank-Starling mechanism

Question 47

how does afterload effect SV?

Answer 47

increases in afterload tend to reduce SV