Physiology of the Heart

Question 1

Used to describe a collection of mechanisms that influence the active and changing circulation of blood circulation of different volumes of blood per minute at different times is essential for survival

Answer 1

hemodynamics

Question 2

the circulation control mechanisms must accomplish 2 function:

Answer 2

• maintain circulation (keep blood flowing) - Vary volume and distribution of the blood circulated

Question 3

A complete heartbeat, or pumping cycle, consisting of contraction (systole) and relaxation (diastole) of both atria and both ventricles

Answer 3

the cardiac cycle

Question 4

contraction of both ventricles of the heart, forcing blood out of these chambers. The atria are in a relaxed state

Answer 4

systole

Question 5

The top number of BP, which is also the higher of the 2 numbers, measures the pressure in the arteries when the heart beats (contracts)

Answer 5

systolic

Question 6

The bottom number, which is also the lower of the 2 numbers, measures the pressure in the arteries between heartbeats (when heart muscle is resting between beats and refilling with blood)

Answer 6

diastolic

Question 7

ventricular muscles relax, allowing for blood to fill these chambers. At the end, the atria start contracting to fill the ventricles

Answer 7

diastole

Question 8

an electrical fluctuation that travels along the surface of a cell’s membrane mediated by the flow of sodium and potassium ions across the membrane; occurs in nerves and muscles.

Answer 8

action potential

Question 9

• repeatedly generate action potentials that trigger contraction and continue to stimulate heart even after it has been removed from the body

Answer 9

autorhythmic cardiac muscle fibers

Question 10

_____, _____, and _____ can alter heartbeat strength and heart rate, but do not change the coordinated contractions of the heart

Answer 10

hormones, chemicals, and nerve impulses

Question 11

Conduction system of the heart has 4 structures:

Answer 11

• sinoatrial (SA) node - Atrioventricular (AV) node - AV bundle (bundle of His) - subendocardial branches (purkinjie fibers)

Question 12

• The natural or inherent “pacemaker” of the heart - Initiates each heartbeat and and sets it pace - located high in r atrial wall

Answer 12

sinoatrial node

Question 13

impulses spread from the ______ to the muscle fibers of both atria causing atrial contraction

Answer 13

SA node

Question 14

The _____ fires between 60-100 BPM

Answer 14

SA node

Question 15

• Located at the base of the right atrium - electrically, it acts as the only gateway for electrical impulses from the atria to the ventricles

Answer 15

Atrioventricular node (AV)

Question 16

electrical activity travels very slowly through the _______. The delay allows for contraction of the atria to proceed contraction of the ventricles.

Answer 16

AV node

Question 17

AV node stimulation sends impulses to the ________.

Answer 17

atrioventricular bundle of His

Question 18

carries electrical impulses (action potentials) into the ventricles. Impulses travel through the right and left bundle branches to the Purkinjie fibers.

Answer 18

bundle of His

Question 19

fibers that further spread electrical activity to all parts of the ventricles so that there is a coordinated contraction of each ventricle.

Answer 19

subendocardial branched AKA Purkinjie fibers

Question 20

a graphic record of the heart’s electrical activity, specifically the conduction of impulses. It is not a record of the heart’s contractions, but of the electrical events/current that precede them a composite record of action potentials produced by the heart muscle fibers during each heartbeat.

Answer 20

electrocardiogram (ECG)

Question 21

In an ECG, changes in voltage are seen as _______ of a line drawn on a paper or traced on a video monitor.

Answer 21

deflections

Question 22

The _______ is composed of deflection waves called the P wave, QRS complex, and T wave.

Answer 22

normal ECG

Question 23

A _______ obtains 12 electrical tracings of the heart from different angles or orientations. Patterns of abnormalities can indicate areas of abnormal conduction.

Answer 23

12-lead ECG

Question 24

represents depolarization of the atria. Deflection related to passage of an electrical impulse from the SA node through the muscle of both atria.

Answer 24

The P wave

Question 25

larger _______ indicate enlargement of an atria.

Answer 25

P waves

Question 26

represents depolarization of the ventricles and repolarization of the atria

Answer 26

the QRS complex

Question 27

represents ventricular repolarization. It is flatter than normal when the heart is not getting enough oxygen.

Answer 27

the T wave

Question 28

the length of time for atrial depolarization and conduction from the SA node to the AV node. (Beginning of the P wave to the beginning of the QRS complex)

Answer 28

P-R interval

Question 29

The time period from the end of ventricular depolarization through ventricular repolarization. Clinically, unhealthy myocardium can affect the height of this interval (either upward or downward)

Answer 29

ST interval/segment

Question 30

The ________ begins at the end of the S wave and ends at the beginning of the T wave.

Answer 30

ST interval/segment

Question 31

- a complete heartbeat consisting of systole and diastole of both atria and ventricles - the 2 atria contract simultaneously filling the ventricles more efficiently - as the atria relax, the two ventricles contract, instead of the entire heart contracting as one unit. Allow for pumping of the heart

Answer 31

the cardiac cycle

Question 32

the 5 important events of the cardiac cycle:

Answer 32

- atrial systole - isovolumetric ventricular contraction - ejection - isovolumetric ventricular relaxation - passive ventricular filling

Question 33

- begins with the P wave of the ECG - atria contract simultaneously completing emptying blood out of the atria into the ventricles - AV valves are open; SL valves are closed - Ventricles are relaxed and filling with blood

Answer 33

atrial systole

Question 34

- onset of ventricular systole coincides with right wave and appearance of the first heart sound (S1), as the AV valves close - between the start of ventricular systole and the opening of the SL valves - volume in the ventricles remains constant as the pressure increases rapidly

Answer 34

isovolumetric ventricular contraction

Question 35

pressure increases enough to open the aortic and pulmonary SL valves and blood is ejected from the heart. - blood enters the systemic and pulmonary circulations via the aorta and pulmonary artery - this period coincides with the ST interval

Answer 35

ejection

Question 36

the blood that remains in the ventricles at the end of the ejection period (roughly half)

Answer 36

residual volume

Question 37

in heart failure the residual volume remaining in the ventricles may greatly exceed that ejected during systole.

Answer 37

ejection fraction

Question 38

beings with an isovolumetric period - occurs between closure of the SL valves and opening of the AV valves - closure of the SL valves produce the second heart sound (S2) - corresponds to the T wave and continues until the next P wave

Answer 38

isovolumetric ventricular relaxation there is a dramatic fall in intraventricular pressure

Question 39

- returning venous blood increases intraatrial pressure until the AV valves are forced open and blood rushes into the relaxing ventricles - results in a dramatic increase in ventricular volume before the atria conract - lasts about 0.1 sec

Answer 39

passive ventricular filling

Question 40

the amount of blood that flows out of a ventricle of the heart per unit of time

Answer 40

cardiac output

Question 41

is measured by the ml of blood pumped out of the left ventricle in one stroke (beat)

Answer 41

stroke volume

Question 42

cardiac output (ml/minute) = ______ (ml/beat) x heart rate (beats/minute) = ml/minute

Answer 42

stroke volume

Question 43

CO = SV x \_\_\_

Answer 43

HR

Question 44

\_\_\_\_ are created by blood turbulence and vibration as valves close

Answer 44

heart sounds

Question 45

the act of listening to sounds within the body

Answer 45

auscultation

Question 46

using the bell of a stethoscope is most useful for _____ and may work best with pediatric patients

Answer 46

low sounds

Question 47

using the diaphragm is most useful for \_\_\_\_\_\_.

Answer 47

higher pitch sounds

Question 48

degree of stretch on the heart prior to contraction

Answer 48

preload

Question 49

forcefulness on contraction of individual ventricular muscle fibers

Answer 49

contractility

Question 50

pressure that must be exceeded before the ejection of blood from the ventricles can occur

Answer 50

afterload

Question 51

pathophysiology: - reduction of blood flow to the myocardium - leading cause of death for men and women - atherosclerosis/arteriosclerosis

Answer 51

CAD

Question 52

pathophysiology: - physiological: hypertrophy related to fitness training - pathological: related to heart disease

Answer 52

cardiomegaly

Question 53

pathophysiology: - loss of pumping efficiency by the heart - caused by CAD, congenital defects, long term high BP, valve disorders

Answer 53

CHF

Question 54

heart rate higher than the normal SA node range of 60-100

Answer 54

tachycardia

Question 55

a resting heart rate under 50 BPM

Answer 55

bradycardia

Question 56

Answer 56

Question 57

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Question 58

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Question 59

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Question 60

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Question 61

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Question 62

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Question 63

Answer 63