Nbde Biochemistry/physiology Hrt

Front 1

Which cardiac muscle has a longer refractory period?
How long is it?

Back 1

Ventricular muscle
0.25 to 0.3 sec.

Front 2

What is responsible for preventing the heart from undergoing reentry, which would not allow the heart to relax and refill with blood?
What does this keep the muscle from undergoing?

Back 2

Long refractory period or Absolute refractory period
Tetanus

Front 3

What increases the strength of cardiac contractions?

Back 3

Increase in extracellular Ca++

Front 4

What is the time required for the excitation to spread throughout the heart?

Back 4

0.22 sec.

Front 5

What period occurs when another action potential cannot be elicited, no matter how large the stimulus?
What determines this period?

Back 5

Absolute Refractory Period
Duration of sodium inactivation gate closure

Front 6

What period begins at the end of the absolute refractory period and continues until the membrane potential returns to the resting level? A second action potential is possible only if the stimulus is larger than usual.

Back 6

Relative refractory period.

Front 7

What valve is located between the right atrium and right ventricle, surrounding the AV orifice?

Back 7

Tricuspid valve

Front 8

What valve is located between the left atrium and left ventricle, surrounding the AV orifice, and is the only valve to have a different number of cusps than the others?

Back 8

Mitral valve

Front 9

What opens the tricuspid and mitral valves?
What closes them?

Back 9

Ventricular diastole
Forced shut as pressure in ventricles increases

Front 10

What valves are opened during ventricular systole?

Back 10

Pulmonary semilunar valve
Aortic semilunar valve

Front 11

The T wave of an electrocardiogram wave segment represents the _____ of the _____.

Back 11

Repolarization
Ventricles

Front 12

What is the test that measures the electrical activity of the heart?
What is the natural pacemaker of the heart?

Back 12

Electrocardiogram (ECG or EKG)
Sinoatrial node

Front 13

What are the principal ECG intervals represented by?

Back 13

P waves
QRS waves
T waves

Front 14

What is the electrical recording from the body surface of atrial depolarization and precedes atrial contraction?

Back 14

P wave

Front 15

What wave represents ventricular depolarization?

Back 15

QRS complex

Front 16

What represents closure of the AV valves at the onset of systole?

Back 16

First heart sound

Front 17

What represents closure of the semilunar valves at the onset of diastole?

Back 17

Second heart sound

Front 18

What does it mean if an ECG shows extra P waves before each QRS complex?

Back 18

Partial heart block

Front 19

What does it mean if an ECG shows the P wave and the QRS complex being dissociated?

Back 19

Complete heart block

Front 20

Cardiac function is the volume of blood pumped each minute, and is expressed by what equation?

Back 20

CO=SV x HR

Front 21

What is perhaps the single most important factor that is used in relation to the circulation and is responsible for transport of substances to and from the tissues?

Back 21

Cardiac output (CO)

Front 22

what is the avg. resting CO?

Back 22

5.6 L/min. - Men
about 10-20% less in women

Front 23

What is directly proportional to cardiac output, and is an intrinsic factor of the SA node in the heart and is modified by _____, _____, and _____ factors?

Back 23

Heart Rate (HR)
autonomic
humoral
local

Front 24

What is determined by three factors; preload, afterload, and contractility?

Back 24

Stroke Volume (SV)

Front 25

What is normal avg. human heart rate?

Back 25

80-100 beats per minute

Front 26

What gives the volume of blood that the ventricle has available to pump, as well as the end diastolic length of the muscle?

Back 26

Preload

Front 27

What is the force that the muscle can create at the given length?

Back 27

Contractility

Front 28

What is the arterial pressure against which the muscle will contract?

Back 28

Afterload

Front 29

What is the equation for stroke volume?
What is the avg.?

Back 29

SV = End diastolic volume - End Systolic volume
70-80ml

Front 30

What is the sum of the resistance of all peripheral vasculature in the systemic circulation?

Back 30

Total peripheral volume (TPR)

Front 31

What is the equation for blood pressure?

Back 31

BP = CO x TPR

Front 32

The bainbrain reflex also called the _____ reflex, is an increase in heart rate due to an increase in the blood volume.

Back 32

Atrial

Front 33

The bainbridge reflex increases HR and CO, which then transfers blood volume where? to where?

Back 33

From pulmonary circulation to systemic circulation

Front 34

What is the dominant cardiovascular mechanism responsible for the control of blood pressure?

Back 34

Baroreceptor reflex

Front 35

What nerves transmit signals from the stretch receptors in the carotid sinus and aortic arch to the solitary nucleus located in the cardiovascular center of the medulla?

Back 35

Glossopharyngeal and Vagus nerves

Front 36

How long does a cardiac cycle last?

Back 36

0.8 seconds

Front 37

In the _____ phase, the heart ventricles are relaxed, and the heart fills with blood.
In the _____ phase, the ventricles contract and pump blood into the arteries

Back 37

Diastole
Systole

Front 38

Blood flow to the coronary arteries would be greatest during _____ _____ in a resting individual.

Back 38

Ventricular relaxation

Front 39

Ventricular volume is _____ following atrial systole.
Ventricular pressure is _____ during ventricular ejection.

Back 39

Greatest
Greatest

Front 40

The first heart sound or _____ is associated with the closure of the _____ valves at the beginning of ventricular contraction.

Back 40

Lub
Atrioventricular (mitral and tricuspid)

Front 41

Which sound is louder and longer?

Back 41

First heart sound

Front 42

The second heart sound or _____ is associated with the closure of the _____ valves as the ventricles begin to relax following their contraction.

Back 42

Dub
Semilunar valves (pulmonary and aortic)

Front 43

_____ begins with the second heart sound

Back 43

Diastole

Front 44

The aortic valve closes _____ the pulmonary valve; this causes _____ of the second heart sound.

Back 44

Before
Splitting

Front 45

What arises from the fact that cardiac myocytes are electrically coupled to one another via gap junctions?

Back 45

Cardiac conduction system

Front 46

What is located within the posterior wall of the right atrium near the opening of the superior vena cava, and contains specialized pacemaker cells that depolarize at an intrinsic rate that drives the depolarization of the remainder of the heart?

Back 46

SA (sinoatrial node)

Front 47

What rapidly transmits the wave of depolarization to the left atrium and to the AV node?

Back 47

Internodal pathways

Front 48

What is located within the lower right interatrial septum, and delays an impulse for about _____ seconds to allow the atria to contract before ventricular contraction?

Back 48

AV (atrioventricular node)
0.13

Front 49

What originates in the AV node, dividing into two bundle branches that extend down the two sides of the interventricular septum?

Back 49

AV bundle (bundle of his)

Front 50

What originates from the right and left bundle branches, extending to the papillary muscles and lateral walls of the ventricles? The wave of depolarization hear is extremely fast.

Back 50

Purkinje fibers

Front 51

What represents atrial depolarization prior to the atria's contraction?

Back 51

P wave

Front 52

What represents ventricular repolarization?

Back 52

T wave

Front 53

What represents ventricular depolarization?

Back 53

QRS complex

Front 54

What represents the period when the ventricles are depolarized and is isoelectric?

Back 54

S-T segment

Front 55

What represents the length of time between depolarization of the atria and depolarization of the ventricles?

Back 55

P-R interval

Front 56

What represents the period between ventricular depolarization and the ventricles' repolarization?

Back 56

Q-T interval

Front 57

What is the most important determining factor for preload?

Back 57

Venous return

Front 58

Under steady state conditions, venous return must equal _____ when averaged over time because the cardiovascular system is essentially a closed loop.

Back 58

CO (cardiac output)

Front 59

Blood flow is directly proportional to the pressure difference between the two ends of the vessel but is inversely proportional to the fractional resistance to the blood flow through a vessel. This relationship can be expressed as:

Back 59

Flow = pressure difference / resistance

Front 60

Factors which influence resistance are expressed as:

Back 60

Resistance = viscosity (of blood) x length (of vessel) / radius^4

Front 61

The _____ the vessel the _____ resistance.

Back 61

Larger
Less

Front 62

What are the factors that influence venous return?

Back 62

Skeletal muscle contraction
Decreased venous compliance
Respiratory activity
Vena cava compression

Front 63

An increase in _____ activation decreases venous compliance and increases _____ ____.

Back 63

Sympathetic activation
Venous return

Front 64

An increase in _____ _____ will decrease venous return.

Back 64

Intrathoracic pressure

Front 65

During exercise, the total peripheral resistance (TPR) is caused by the accumulation of what?

Back 65

Vasodilator Metabolites (lactate, potassium ions, adenosine)

Front 66

What accounts for the overal decrease of TPR?

Back 66

Arterial vasodilation

Front 67

When you have an anxious dental patient that may have a higher systolic blood pressure than previously noted, what is this most likely due to?

Back 67

Decreased arterial compliance

Front 68

What primarily controls Heart rate?
Where is the control of this system take place?

Back 68

ANS
Medulla oblongata

Front 69

Parasympathetic fibers innervate the heart by way of the _____ nerves. The _____ _____ goes to the SA node and the _____ _____ goes to the AV node.

Back 69

Vagus
Right vagus
Left vagus

Front 70

Where do the sympathetic fibers of the heart which increases cardiac function come from?

Back 70

First four thoracic spinal nerves (accessory nerves)

Front 71

If a patient's SA and AV nodes fail, what is the most likely situation the patient will be in?

Back 71

Both atria and ventricles will continue to contract on the pace of the bundle of His (30-40 impulses)

Front 72

What makes up the AV junctional tissue?
Where is this considered to be located?
What is its intrinsic rate or beats per minute?

Back 72

AV node and Bundle of His
Supraventricular
40-60 beats per minute

Front 73

What are the three bundle branches of the Bundle of His?
What does this comprise?

Back 73

Rt.
Lt. anterior-superior
Lt. posterior-inferior

Trifascicular system

Front 74

What are the fibers which conducta signal from the bundle of His to the ventricular muscles?

Back 74

Purkinje fibers

Front 75

what is the system of the Bundle branches and Purkinje fibers known as?

Back 75

Ventricular conduction system