Cardiac Rhythm And Its Regulation & Control

Front 1

What is the relationship between the area of a blood vessel and the resting velocity of the blood that flows through it?

Back 1

inversely proportional

Front 2

What does the inversely proportionate relationship of vessel size and velocity say about capillaries?

Back 2

blood moves very quickly through capillaries

Front 3

What are the 3 basic underlying principles of the circulatory system?

Back 3

1. Rate of blood flow is controlled by the individual needs of each tissue (microvessels monitor O2, CO2 and nutrients), 2. Cardiac output is controlled by the sum of all local tissue flows (venous return increases output), 3. Arterial pressure is controlled independently of local blood flow and cardiac output (nervous systen in response to arterial pressure: a) increase force of heart pumping, b) contraction of large venous reservoirs to send more blood to the heart, c) constriction of artriole to divert more blood to the main arteries and raising blood pressure.

Front 4

State Ohm's Law with respect to Flow, pressure and resistance.

Back 4

F=(P1-P2)/R=∆P/R

Front 5

What does Ohm's law say about the relationship between flow and the difference in pressure?

Back 5

it is proportional to the pressure difference

Front 6

What does Ohm's law say about the relationship between flow and the resistance?

Back 6

it is inversely proportional

Front 7

Chapter 16

Front 8

How is resistance affected by increased pressure (vessel distensibility)? What effect will this have on flow?

Back 8

increased pressure -> vessel dialation -> decreased resistance -> increased flow

Front 9

Besides its role in adjusting blood flow, what can be said about vessel distensibility's role?

Back 9

it plays a role in blood storage (resevoir)

Front 10

What fraction of sinuses in the heart are cornary?

Back 10

3-Feb

Front 11

All valves are tricuspid except which?

Back 11

the mitral valve which is a bicuspid valve

Front 12

What of the mitral vavle leaflet is larger?

Back 12

the Anterior leaflet, nearest the Aorta

Front 13

What are the 3 functions of the pericardium? (on is a role in pathology)

Back 13

1. Limits acute chamber dialation, 2. Controls ventricular interaction, 3. In pathology it often defines pathology

Front 14

From superior to inferior, what are the branches of the right coronary artery, and what do they serve?

Back 14

SA node artery (right atrium), Acute marginal arteries ( right ventricle), Posterior left ventricular branches (right ventricle), Posterior descending artery Vendricle), AV node artery(right atrium)

Front 15

What are the branches of the left coronary artery and what do they serve?

Back 15

Left anterior descending (left ventricle), left circumflex artery (left ventricle), Septal branches (left ventricle), Diagonols (left ventricle), obtuse marginal arteries (left ventricle), left atrial circumflex artery (left atrium)

Front 16

What disease is associated with the sinus node artery?

Back 16

sinus arrest

Front 17

What disease is associated with AV node artery?

Back 17

Heart block

Front 18

What two disease are associated with PDA (Posterior descending artery)?

Back 18

Septum and posteromedial papillary muscles

Front 19

What disease is associated with posterior left ventricular branches?

Back 19

posterior wall

Front 20

What disease is associated with acute marginal arteries?

Back 20

Right ventricle infection

Front 21

Which right coronary artery is most commonly associated with disease?

Back 21

acute marginal arteries

Front 22

Which two diseases are associated with Left anterior descending artery?

Back 22

Anteroseptal infarct, cardiogenic shock

Front 23

Which three diseases are associated with the circumflex artery?

Back 23

Posterior/inferior infection, Anteriolateral papilary muscle (often jointly with LAD)

Front 24

Chapter 10

Front 25

Do fast sodium channels cause the action potential in the sinus node? Why?

Back 25

No, because the resting potential is about -55, so fast sodium channels would have already been inactivated at this voltage… thus they are blocked

Front 26

What causes the action potential in sinus nodal fibers? (Hint: comparet the AP curves of the sinus nodal fibers with the ventricle AP.)

Back 26

slow Na-Ca channels.. Which means that the atrial nodal potential is slower to start… compare the AP curves

Front 27

Which ionic flux causes the rise in membrane potential in sinus nodal tissue toward threshold? Why does this happen?

Back 27

Na, because of high extracelluar concentration and a moderate number of Na channels already being open.

Front 28

In sinus nodal tissue, at what membrane potential is the threshold for AP? Which channels open at this threshold?

Back 28

minus 40mV, Slow Na/Ca channels

Front 29

Which "leaky" ionic flow causes the self-excitation of sinus nodal fibers?

Back 29

Na/Ca

Front 30

Why don't sinus nodal fibers remain depolarized?

Back 30

Na/Ca channels close shortly after opening, at the same time K+ channels are opening (they stay open longer) and as such they are lowering the membrane potential.

Front 31

What complete the cycle for sinus nodal fibers?

Back 31

K+ channels close, while Na/Ca channels begin to leak once more

Front 32

What is the conduction pathway in the heart that allows the atria to contract followed .6 sec later by ventricle contraction?

Back 32

Sinus nodal fibers are self-excited -> transmission to atrial muscles and conduction to the A-V node (Delayed conduction) -> to bundle of HIS (fast conducting) -> purkinje system -> ventricle

Front 33

Can conduction travel back from the ventricle to the atria?

Back 33

no

Front 34

Which has the fastest intrinsic HR, SA node, A-V node or purkinje fibers?

Back 34

SA node… this is why it's the pacemaker of the heart.

Front 35

What is an ectopic pacemaker?

Back 35

when the HR is set by a part of the heart other than the SA node, e.g., A-V node or purkinje

Front 36

What is the most common pacemaker in an ectopic pacermaker when there is SA node blockage?

Back 36

A-V node

Front 37

What occurs when there is a A-V blockage? What is this called?

Back 37

there is a delay purkinje pacemaker HR set for the ventricles… the delay can be as much as 5-20 seconds later… causing fainting or death. Stokes-Adams syndrome

Front 38

What branch of the ANS controls the rate of the SA-node? And which NT?

Back 38

parasympathetic, ACh

Front 39

What clinical effects does ACh have on the SA-node? What is the chemical effect does ACh have on the cells membrane?

Back 39

a) slow the HR and it decreases the excitability of SA-junctional fibers and thereby slow conduction to the ventricles. b) it increases K+ permeability causing hyperpolarization (below -55mV), making the tissues less excitable

Front 40

What 3 effects does the sympathetic NS have on cardiac rhythm and conduction?

Back 40

1) It increase the SA node discharge and 2)raises the level of excitability in all parts of the heart. 3) increases the force of contraction.

Front 41

What does the sympathetic NS release to the heart? What is thought to be the mechanism by which this NS works?

Back 41

Norepinephrine, increase Na/Ca permeability