Sfos Test Ii 16 Regulation Of Cardiac Function

Front 1

Define: the volume of blood pumped into the aorta during one cardiac cycle.

Back 1

Stroke volume

Front 2

Define: the volume of blood that is pumped into the aorta per unit of time (L/min)

Back 2

Cardiac output

Front 3

Define: Cardiac output/BSA (body surface area); often used clinically to compare cardiac outputs of individuals who differ markedly in size.

Back 3

Cardiac index

Front 4

What is the Fick principle?

Back 4

In a steady state, the rate of indicator (dye) leaving the system must equal the rate at which it enters plus the rate at which it was added

Front 5

How is the the Fick principle used to measure cardiac output?

Back 5

Oxygen consumption is used as the indicator. Oxygen consupmtion using inspired and expired air is determined to calculate oxygen content introduced in lung; blood samples are taken to measure arterial and venous oxygen contents to determine consumption.

Front 6

What effect does wall stress have on volume and pressure?

Back 6

The greater the wall stress the more contractility is able to be generated.

Front 7

Define: the power developed by the muscle for any given sarcomere length independent of preload and afterload.

Back 7

Contractility/inotropic state

Front 8

Give another term for contractility.

Back 8

inotropic state

Front 9

Define: the volume of blood pumped into the aorta during one cardiac cycle.

Back 9

Stroke volume

Front 10

Define: the volume of blood that is pumped into the aorta per unit of time (L/min)

Back 10

Cardiac output

Front 11

Define: Cardiac output/BSA (body surface area); often used clinically to compare cardiac outputs of individuals who differ markedly in size.

Back 11

Cardiac index

Front 12

What is the Fick principle?

Back 12

In a steady state, the rate of indicator (dye) leaving the system must equal the rate at which it enters plus the rate at which it was added

Front 13

How is the the Fick principle used to measure cardiac output?

Back 13

Oxygen consumption is used as the indicator. Oxygen consupmtion using inspired and expired air is determined to calculate oxygen content introduced in lung; blood samples are taken to measure arterial and venous oxygen contents to determine consumption.

Front 14

What effect does wall stress have on volume and pressure?

Back 14

The greater the wall stress the more contractility is able to be generated.

Front 15

Define: the power developed by the muscle for any given sarcomere length independent of preload and afterload.

Back 15

Contractility/inotropic state

Front 16

Give another term for contractility.

Back 16

inotropic state

Front 17

If preload is increased what is the effect on measured ventricular volume and pressure?

Back 17

It increases

Front 18

If afterload is increased what is the effect on measured ventricular volume and pressure.

Back 18

It decreases

Front 19

What are the effects of greater developed tension or greater stroke volume on cardiac work?

Back 19

Both a greater developed tension and greater stroke volume increase cardiac work (which in turn increases cardiac output)

Front 20

After/preload ___________ is approximated by the systolic pressure in the artery outside the ventricle.

Back 20

Afterload

Front 21

After/preload ___________ is approximated by intraventricular pressure (EDP) at end-diastolic volume (EDV)

Back 21

Preload

Front 22

_______ determines the rate and magnitude of force generated by the cardiac muscle, and therefore the magnitude of the endsystolic volume (ESV).

Back 22

Contractility

Front 23

What does the Frank-Starling mechanism ensure?

Back 23

That cardiac output = cardiac input

Front 24

What determines myocardial fiber length at the onset of contraction?

Back 24

Preload (or EDV or its surrogate EDP)

Front 25

What causes the increase in contractility caused by an increase in preload?

Back 25

Greater exposure of calcium binding sites on the actin/myosin duo in the heart cells.

Front 26

Define: (EDV-ESV)/EDV

Back 26

Ejection fraction

Front 27

What currents (calcium, potassium, sodium) need to be augmented to increase the slope of diastolic depolarization?

Back 27

Two: the inward sodium current, and inward calcium current which exceed the nehancement of an outward rectifier potassium current.

Front 28

If sinus nodal tissue reaches threshold for self-excitation faster, what effect does this have on the rthym?

Back 28

Decreases the period or increases the frequency

Front 29

What two effects does the sympathetic nervous sytem have on the myocardium tissue in the heart?

Back 29

Phosphorylation of two proteins which impact cardiac function. 1. specific sarcolemmal proteins which activates long-lasting calcium channesl in myocardial cell membranes augmenting calcium inflow from interstitial fluid 2. Phosphorylation of phospholambam facitiltates the reuptake of calcium by the sarcoplasmic reticulum

Front 30

In what three ways does the sympathetic nervous system increase heart rate?

Back 30

Increase rate of sinus nodal discharge, increases rate of conduction and increases excitability in all portions of the heart

Front 31

How does the sympathetic nervous system effect the conduction system cells?

Back 31

Beta-andrenergic receptors in the nodal region (also in the myocardium) bind to norepinephrine (or circulating catecholamines) activate adnylyl cyclase which raises intracellular cAMP which promotes phosphoraylation of various proteins within the cell. Ultimately this leads to an increase in the slop fo diastolic depolarization which decreases the time between Action Potentials.

Front 32

Simply put, what is the effect of sympathetic stimulation on membrane permeability?

Back 32

It increases it via phosphorylation

Front 33

What is the overall effect of parasympathetic stimulation on heart rhythm and conduction?

Back 33

It slows or blocks cardiac rhythm and conduction

Front 34

Describe the two effects on membrane bound adenylyl cyclase by parasympathetic stimulation.

Back 34

Releases ACh which binds to muscarinic receptors resulting in inhibition of adenylyl cyclase causing falling of intracellular levels of cAMP.

Front 35

How does release of Acetylcholine by parasympathetic innervation affect the membrane permeability of potassium.

Back 35

Increases membrane permeability to potassium resulting in a net outward leakage of potassium.

Front 36

What is the effect of parasympathetic nervous system on the rhythmicity of the heart?

Back 36

The increased potassium permeability and decreased levels of cAMP decreases the slope of phase 4. More sodium needs to leak out of the hyperpolarized cell to reach threshold, resulting in longer 'wait' times.

Front 37

What is the effect of parasympathetic nervous system on the nodal fiber excitation and AP transmission?

Back 37

Due to the hyperpolarization, it is more difficult for atrial impulses to excite nodal fibers and AV conduction time is prolonged. The greater the hyperpolarization the more impaired the AV conduction will b e.

Front 38

Define: Heart rate may decrease to zero under the influence of strong parasympathetic stimulation driving the membrane potential very negative in the A-V node.

Back 38

vagally-mediate dheart block or atrioventricular block.

Front 39

What is the effect of the parasympathetic nervous system on the myocardium?

Back 39

the inhibition of cAMP ultimately decreases calcium conductance resulting, there is minimal effect on the ventricles, because vagal fibers are primarily distributed in the atria.

Front 40

Why is the effect of the parasympathetic nervous system on the ventricles minimal?

Back 40

Vagal fibers are primarily only distributed in the atria.

Front 41

What effect does acetylcholine released from vagal ending have on the release of norepinephrine from neighboring sympathetic nerve endings?

Back 41

Inhibits

Front 42

True/False: Sympathetic tone ordinarily predominates in healthy resting individuals.

Back 42

False, parasympathetic tone (decreased heart rate)

Front 43

True/False: changes in heart rate usually involve a reciprocal action of the two divisions of the autonomic nervous system.

Back 43

TRUE

Front 44

What is the effect of sympathetic stimulation on cardiac output?

Back 44

Increases cardiac output

Front 45

True/False: sympathetic stimulation may decrease storke volume due to a decreased filling time.

Back 45

TRUE

Front 46

How does sympathetic stimulation effect the level of intracellular caclium available to interact with the contractile elements?

Back 46

Increases the amount, driving an increase in cardiac metabolism.

Front 47

What effect does sympathetic activity have on oxygen consumption and cardiac metabolism in general.

Back 47

Increases it.