#27

Question 1

Heart Rate

Answer 1

the number of times your heart beats per munite [BPM]

Question 2

Stroke Volume

Answer 2

The volume of blood [mL] ejected into the artery per cardiac cycle [mL/beat]

Question 3

End diastolic Volume

Answer 3

Amount of blood in a ventricle and the end of ventricular diastole

Question 4

Ejection Fraction

Answer 4

percentage of end diastolic volume that is released during the ejection phase

Question 5

End systolic volume

Answer 5

Amount of blood remaining in the ventricle at the end of ventricular systole

Question 6

Isometric contraction

Answer 6

early ventricular systole phase where the heart muscle contracts, without a change in blood volume as blood has nowhere to exit

Question 7

Isometric relaxation

Answer 7

Early diastolic phase where ventricles relax with all the heart valves close causing a rapid drop in intraventricular pressure without changing volume

Question 8

Cardiac Output

Answer 8

the volume of blood pumped into the aorta by the left ventricle each minute

Question 9

Cardiac Output equation

Answer 9

CO = HR x SV

Question 10

Atrial Reflex

Answer 10

heart-rate increase in response to increased blood volume stretching the right atrium

Question 11

Body Temperature or Exercise and Heart Rate

Answer 11

Rises with increased body temperature and lowers with a drop in body temperature

Question 12

Autonomic Nervous system and Heart rate

Answer 12

sympathetic stimulation increases HR
parasympathetic stimulation decreases HR

Question 13

Notable hormones that increase heart rate

Answer 13

epinephrine and thyroxine

Question 14

Exercise and stroke volume

Answer 14

muscular contractions compress veins and assist valces in directing venous blood towards the atrium

Question 15

What does a decrease in blood volume do for venous return?

Answer 15

Reduced venous return because not much block flowing back to the right atrium

Question 16

What can changes in blood flow patterns do for Venous return

Answer 16

can decrease it

Question 17

Venous Return

Answer 17

Rate of blood flow back to the heart’s right atrium
When it decreases, stroke volume also decreases

Question 18

Preload

Answer 18

amount the ventricles stretch at the end of diastol

Question 19

Filling Time

Answer 19

Phase in the cardiac cycle where the heart relaxes and fills with blood

Question 20

Contractility

Answer 20

Strength of cardiac cells to contract/shorten

Question 21

Frank-Starling Law

Answer 21

The stroke volume of the heart increases in response to an increase in the volume of blood filling the heart (end-diastolic volume/preload)
As more blodo enters the ventricle, cardiac muscle fibers stretch causing a more forceful contraction and increased cardiac output

Question 22

Vasoconstriction

Answer 22

Vessels narrowing caused by contraction of muscular walls reducing blood flow and increasing blood pressure

Question 23

Vasodilation

Answer 23

Widening of blood vessels due to smooth muscle relaxation, increasing blood flow and reducing blood pressure

Question 24

Afterload

Answer 24

The force the ventricles must work against to open the semilunar valves to pump blood out of the heart

Question 25

ECG

Answer 25

recording of the heart's electrical activity

Question 26

phonocardiogram

Answer 26

Heart sounds of the valves closing

Question 27

What's the first sound of the valve closing on the phonocardiogram?

Answer 27

first sound is the sudden closure of mitral and tricuspis valves as ventricular pressure rises

Question 28

What is the second sound on a phonocardiogram?

Answer 28

closure of aortic and pulmonary valves

Question 29

P-wave

Answer 29

represents depolarization, electrical signal travelling through the atria

Question 30

QRS complex

Answer 30

depolarization of ventricles. ventricular contraction in systole

Question 31

T-wave

Answer 31

ventricular repolarization

Question 32

When does atrial systole happen?

Answer 32

With the filling of the ventricles, triggered by SA node's electrical impulse

Question 33

Ventricular systole

Answer 33

involves a brief period of isovolumetric contraction and then a period of ventricular ejection

Question 34

Ventricular ejection

Answer 34

semilunar valves open, allowing stroke volume to be squeezed out into the aorta

Question 35

Ventricular diastole

Answer 35

begins and the semilunar valves close

Question 36

Filling times relation to ventricular diastole

Answer 36

The duration of ventricular diastole which determines the time the AV valves are open

Question 37

How are EDV and preload affected by venous return? (high)

Answer 37

Higher venous return means more blood being delivered to right atrium. increased filling stretches more and results in a stronger contraction

Question 38

End diastolic volume

Answer 38

volume before contraction, at the end of filling

Question 39

How are EDV and preload affected by venous return? (low)

Answer 39

Low means less blood. meaning a reduced ventricular wall stretch, resulting in a less forceful contraction

Question 40

How with a semilunar valve open?

Answer 40

When ventricular pressure exceeds the pressure in the its artery (aora or pulmonary)

Question 41

What happens when valve opening is delayed?

Answer 41

Time for ventricular ejection is reduced and less blood is released as systolic volume and more remains as ESV

Question 42

What does filling ventricles do for cardiac myocytes?

Answer 42

stretches cardiac myocytes, optimizing their sarcomere length for maximum force generation

Question 43

what is happening with the actin and myosin filaments when ventricles stretch?

Answer 43

moves the filaments closer toegether which improves the ability of myosin heads to bind with the actin

Question 44

What do stretched sarcomeres exhibit?

Answer 44

higher affinity for calcium which allows for greater force production without needing extra calcium ions

Question 45

Why does cardiac output increase with exercise?

Answer 45

It's a regulated variable subject to homeostatic and allostatic changes, skeletal muscles need more oxygen and nutrients during exercise, producing more waste and thermal homeostasis needs to be maintained

Question 46

How are effects on heart rate made?

Answer 46

primarily through synaptic or hormonal signalling at the cells of the SA nodes through beta-adregenic receptors

Question 47

How do changes in stroke volume during exercise occur?

Answer 47

Thorugh muscle activity, vessel blood flow patterns, sympathetic activity and hormones

Question 48

What are heart rate increases primarily due to?

Answer 48

Reduction in diastole