Physio Lecture 14 (Exam 3)

Front 1

Are the ventricles empty before the atria contract?

Back 1

No, the ventricles are actually only ~70% full, and the atria "top them off".

Front 2

Which side of the heart delivers blood to the pulmonary circuit?

Back 2

Right side

Front 3

Which side of the heart delivers blood to the systemic circuit?

Back 3

Left side

Front 4

Do the pulmonary and systemic circuits contain the same amount of blood?

Back 4

no

Front 5

Are both circuits at the same pressure?

Back 5

No, the systemic circuit is under much greater
pressure. (Systemic systolic pressure ~120 mmHg; Pulmonary systolic pressure ~ 12-14 mmHg).

Front 6

Do both system pump the same amount of blood at the same rate?.

Back 6

Yes, both the
pulmonary and systemic circuits must pump the same amount of blood through each
circuit so that neither one "backs up" the other - they both pump about 70 ml/beat

Front 7

Are left and right ventricles the same size?

Back 7

No, the left ventricle is considerably larger
than the right.

Front 8

Which is longer diastole or systole?

Back 8

During normal contractions, diastole is longer than
systole (normal heart beat - diastole 0.5 sec and systole 0.3 sec).

Front 9

Do the left and right atria contract at the same time?

Back 9

yes

Front 10

Do the left and right ventricles contracts at the same time?

Back 10

yes

Front 11

Do atria and ventricles contract at the same time?

Back 11

No, atria contract
0.1-0.2 sec before ventricles

Front 12

How long is an average cardiac cycle at rest (non-exercising)?

Back 12

0.8 sec

Front 13

What is occurring
during isovolumetric ventricular contraction?

Back 13

The ventricles begin contracting, which closes the AV valves. As isovolumetric contraction continues, pressure is built up within the ventricle until the pressure in the ventricles is great enough to open the semilunar
valves.

Front 14

What are heart murmurs?

Back 14

Heart murmurs are abnormal heart sounds produced by
abnormal blood flow in the heart.

Front 15

What does congenital mean?

Back 15

Congenital means present at birth, but not necessarily
hereditary.

Front 16

What is mitral stenosis?

Back 16

This is a condition in which the mitral valves become
calcified and thickened.

Front 17

What can happen as a result of mitral stenosis?

Back 17

If the mitral valve is calcified and thickened, it does not open properly, so blood can not enter the left ventricle easily, this can cause blood to remain in the atria, and eventually back up into
the pulmonary system causing pulmonary hypertension.

Front 18

What happens to the length of diastole during exercise?

Back 18

During exercise the length of
diastole decreases.

Front 19

If rate is over 200bts/min does it affect the ability of the ventricles to fill?

Back 19

Yes, if the heart rate is over 200 beats/min there is insufficient time for the ventricles to fill.

Front 20

Where is the majority of the blood in your body contained when you are at rest?

Back 20

In the veins of the systemic system.

Front 21

Do all of the cells of the heart contract?

Back 21

No, the conducting cells do not contract.

Front 22

Do all of the contractile heart cells contract with each cardiac cycle? (all-or-nothing)

Back 22

Yes, once
one cell is committed to contract, all the cells in one syncitium become committed to contract because they are all connected by gap junctions, however, the atria acts as one
syncitium (like one giant cell) and the ventricles act as another, so the contraction of the atria does NOT commit the ventricles to directly contract, this is why you must have the
conducting cells to send the depolarization from the atria to the ventricles.

Front 23

Do heart cells always contract with the same force?

Back 23

No, the sympathetic system can cause an increase in availability of internal Ca++. If there is more Ca++, that means that cross bridging can happen faster which will cause the cells collectively to contract more forcibly and more quickly.

Front 24

Is there only one area of the heart with cells that generate spontaneous action potentials?

Back 24

No, all of the conducting cells of the heart can generate spontaneous action potentials.
Even the contracting cells can generate ABNORMAL action potentials called ectopic
beats, these are the primary causes of PVC's. These are abnormal only because the
contracting cells don't generally generate spontaneous action potentials, not because they are connected with a specific disease state.

Front 25

At what part of the heart is the heart rate normally determined?

Back 25

Normally the SA node
sets the pace of the heart because it is depolarizing the quickest.

Front 26

What does “cardiac output” mean?

Back 26

Cardiac output (CO) is the volume of blood pumped per minute from each ventricle

Front 27

What is the equation for cardiac output?

Back 27

CO = HR x SV
(Cardiac output = Heart rate x stroke volume).

Front 28

What factors affect Heart rate?

Back 28

Heart rate is controlled by the ANS (autonomic nervous system).

Front 29

What factors affect stroke
volume?

Back 29

3 factors affect stroke volume 1. EDV (end diastolic volume) 2. TPR (total pheripheral resistance) and 3. Contractility of the heart.

Front 30

What is the average resting
cardiac output?

Back 30

At rest, the average CO is about 5.25L of blood (slightly more than our total blood volume is pumped through the heart every minute).

Front 31

At rest the c.o. is what %
of the total blood volume?

Back 31

~ 105%.

Front 32

During strenuous exercise what is the % of CO in total blood volume?

Back 32

During strenuous exercise up to 25-30L/min of blood can be pumped through the heart ~500% of our total blood volume.

Front 33

What is stroke volume?

Back 33

Stroke volume is the amount of blood ejected per each beat of the
heart.

Front 34

Is stroke volume constant?

Back 34

no

Front 35

What can change stroke volume?

Back 35

The EDV (end diastolic volume) - the amount of blood that has returned to the heart, which can be affected, for example, by the amount of sympathetic activity causing vasoconstriction of arteries and veins or the
activity of the "skeletal muscle pumps". Furthermore, the stroke volume can be affected
by the contractility of the heart. Or the blood pressure of the arteries (if the pressure in the
arteries is too high, not as much blood can be pumped out of the heart).

Front 36

What is the major intrinsic regulator of the force of contraction (stroke volume)?

Back 36

The EDV.

Front 37

What is the Frank-Starling law of the heart?

Back 37

Basically, the more blood returned to the heart (the more EDV), the more blood will be ejected with each beat, this is based on the
relationship of the stretch of the sarcomeres and the ability of actin and myosin to form
cross-bridges.

Front 38

What are chronotropic effects?

Back 38

Chronotropic effects are those which affect heart rate. (Chronos = time)

Front 39

What are inotropic effects?

Back 39

Inotropic effects are those which
affect the contractility of the heart, these are usually associated with ions, such as Ca++.

Front 40

What % of the blood that enters the ventricle during diastole is pumped out during systole?

Back 40

This is referred to as the "Ejection Fraction" and is usually about 60%.

Front 41

Is the ventricle empty at the end of systole?

Back 41

No, if the ejection fraction is ~60%, that means that
about 40% of the blood is still remaining in the ventricles at the end of systole.

Front 42

How do skeletal muscles affect EDV?

Back 42

Without skeletal muscles (especially of the lower
extremities) blood would not be able to return to the heart, and would pool in the foot and
lower leg area. The more skeletal muscle activity, the more blood is returned to the heart. In other words, when you go out and run, you muscles are being used to not only move
you but also to return more blood to the heart at a quicker rate.

Front 43

Pulmonary

Back 43

The closed loop of large vessels carrying blood between the heart and lungs, heart pumps blood to the lungs from the right side of the heart

Front 44

Systemic

Back 44

The closed loop of blood vessels carrying blood between the heart and body system, heart pumps blood to the body system from the left side of the heart

Front 45

Atria

Back 45

Two of four chambers that receive blood from venous system and transfers to the ventricle, found in the upper chambers of the heart

Front 46

Ventricle

Back 46

Two of four chambers that pump blood to the arteries, found in the lower chambers of the heart

Front 47

Septum

Back 47

The think wall that separates the two sides of the heart that act as pumps, the left ventricle and atrium and the right ventricle and atrium

Front 48

Myocardium

Back 48

The cardiac muscle within the heart wall, entire muscle that forms a chamber

Front 49

Aorta

Back 49

A large vessel that carries blood from the left ventricle

Front 50

Pulmonary Artery

Back 50

The large vessel that carries blood from the right ventricle to the lungs

Front 51

Pulmonary Vein

Back 51

The large vessels that carry blood from the lungs to the heart

Front 52

AV (Atrioventricular) valves

Back 52

One way valves that permits blood flows from atria into ventricles during filling of the heart but prevents the backflow of blood from the ventricle to the atrium during emptying of the heart, closing of AV valves produce first heart sounds

Front 53

Tricuspid

Back 53

AV valve between right atrium and ventricle

Front 54

Bicuspid/mitral valve

Back 54

AV valve between left atrium and ventricle

Front 55

Semilunar valves

Back 55

The aortic and pulmonary valves, during ventricular contraction blood is pumped through aortic and pulmonary, and are closed during contraction. Closing of semilunar valves produces second heart sound

Front 56

CO – cardiac output

Back 56

The volume of blood pumped by each ventricle each minute; equals stroke volume times heart rate

Front 57

SA (sinoatrial) node

Back 57

A small specialized autorhythmic region in the right atrial wall of the heart that has the fastest rate of spontaneous depolarizations and serves as the normal pacemaker of the heart

Front 58

Internodal Pathway

Back 58

The pathway found between the SA node and the AV node that creates a temporary pause

Front 59

AV (atrioventricular) node

Back 59

A small bundle of specialized cardiac cells at the junction of the atria and ventricles that is the only site of electrical contact between the atria and ventricles

Front 60

Bundle of His

Back 60

A tract of specialized cardiac cells that rapidly transmits an action potential down the interventricular septum of the heart

Front 61

Purkinje Fibers

Back 61

Small terminal fibers that extend from the bundle of his and rapidly transmit an action potential throughout the ventricular myocardium

Front 62

HCN – hyperpolarization activated cyclic-nucleotide gated

Back 62

Gate is opened during spontaneous depolarization which is caused by Na+ flowing through the channel that opens when hyperpolarized, pacemaker potentials

Front 63

Absolute Refractory Period

Front 64

Plateau Phase (Ca ++)

Back 64

Plateau results from balance between slow Ca++ influx (in) and K+ efflux (out), membrane potential rapidly declines to 15mV and stats there for 200-300 msec

Front 65

SV- stroke volume

Back 65

The volume of blood pumped out of each ventricle with each contraction, or beat of the heart

Front 66

EDV- end diastolic volume

Back 66

The volume of blood in the ventricle at the end of diastole, when filling is complete

Front 67

Ejection fraction

Back 67

= Stroke Volume/End diastolic volume

Front 68

Frank Starling Law of the Heart

Back 68

Intrinsic control of the heart such that increased venous return resulting in increased end diastolic volume leads to an increased strength of contraction and increased stroke volume; that is, the heart normally pumps out all the blood returned to it; states that strength of ventricular contraction varies directly with EDV, as myocardium is stretched more, causes greater contraction and stroke volume

Front 69

Chronotropic Effect

Back 69

The influences on heartrate caused by sympathetic and parasympathetic activity, symp and parasymp nerve fibers modify rate of spontaneous depolarization at the SA node, sympathetic system released NE and EPi which stimulates opening of pacemaker HCN channels, Parasym system releases Ach which promotes opening of K+ channels

Front 70

Inotropic

Front 71

Intrinsic

Back 71

Local control mechanisms inherent to an organ

Front 72

Extrinsic

Back 72

Regulatory mechanisms initiated outside of an organ that alter the activity of the organ; accomplished by the nervous and endocrine systems

Front 73

Skeletal Pump

Back 73

Blood is moved toward heart by contraction of surrounding skeletal muscles

Front 74

Venous Return

Back 74

The volume of blood returned to each atrium per minute from the veins

Front 75

Capacitance Vessels

Back 75

Veins hold most of blood in body, almost 70%, and have thin walls and stretch easily to accommodate more blood without increased pressure (= higher compliance), have only 0-10mmHg pressure

Front 76

Compliance

Back 76

The distensibility of a hollow, elastic structure, such as a blood vessel or the lungs; a measure of how easily the structure can be stretched

Front 77

Isovolumetric Contraction

Front 78

Isovolumetric Relaxation

Front 79

Heart murmurs

Back 79

Abnormal sounds produced by abnormal patterns of blood flow in heart, many caused by defective heart valves, can be congenital origin (present at birth), heart valve defects are not always life threatening

Front 80

Rheumatic Fever

Back 80

Thickened valve from calcium deposits does not open fully impairing blood flow from left atrium to left ventricle, valve acts as if it’s too stiff, this type of damage can be severe because it can lead to accumulation of blood in left atrium and can cause pulmonary hypertension, also causes a secondary damage known as mitral stenosis

Front 81

Mitral Stenosis

Back 81

A type of valve damage in which the mitral valve becomes thickened and calcified very often due to secondary damage from rheumatic fever

Front 82

TPR – total peripheral resistance

Back 82

Impedance to blood flow in arteries

Front 83

tricuspid

Back 83

AV valve between right atrium and ventricle

Front 84

Bicuspid/mitral valve

Back 84

AV valve between left atrium and ventricle