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EXCI 357 Physiology 2 > Lecture two ch 9 & 10 > Flashcards

Lecture two ch 9 & 10 Flashcards

1
Q

What cause the First Heart Sound? What does it signify?

A

Closing of the AV valves ( Mitiral and Tricuspid ).

Signinfies beginning of Systole

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2
Q

Second sound ?

A 
the semilunar (Pulmonary & Aortic) valves close.
Beginning of ventricular diastole
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3
Q

The Frank-Sterling Mechanism would shift the V-P curve towards the right or left?

A

Towards the right. AS the period of filling would be greater, thereby allowing the heart to contract stronger without need to provide any extra work

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4
Q

An increased Preload would shift the VP curve in which direction? WHY?

A

Towards the right. An increased preload means an increased end diaslotic Volume. Which translates and increased ventricular filling

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5
Q

An Increased _____ ____ leads and an increased ____ load and thereby an ____ stroke volume

A

Frank-starling mechanism
Preload
increased SV

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6
Q

An increased After load would effect the VP curve in which way and why?

A

Intially, the stroke volume is reduced and the end-systolic volume increased.

The increased end-systolic volume, however, leads to a secondary increase in end-diastolic volume because more blood is left inside the ventricle following ejection and this extra blood is added to the venous return, thereby increasing ventricular filling. This secondary increase in preload enables the ventricle to contract with greater force (Frank-Starling mechanism), which partially offsets the reduction in stroke volume caused by the initial increase in afterload

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7
Q

Increased Contractility of the heart shifts the VP curve in which direction?

A 
Up and left. 
Increased inotropy (contractility) also increases the rate of pressure development and ejection velocity, which increases stroke volume, and decreases end-systolic volume
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8
Q

When a membrane is permeable to several different ions, the diffusion potential that develops depends on three factors. What are they?

A

1) Polarity of the electrical charge of each ion
2) Permeability of the membrane
3) Concentrations of the respective ions on the inside and outside of the membrane

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9
Q

What is this a description of? Strip of specialized cardiac muscle – flattened ellipsoid strip of cells on the right atrium. Non contractile. Self excitation, 100 BPM

A

SA Node

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10
Q

____ are electrically connected with the atrial muscle fibers

A

Sinus nodal fibers

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11
Q

What causes the self excitation of SA nodal fibers?

A

The inherent leakiness of the sinus nodal fibers to sodium and calcium ions

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12
Q

Where is the internal pace maker of the heart and why?

A

The SA Node
- The inherent leakiness of the sinus nodal fibers to m sodium and calcium ions
(- Atria have to contract first )
- The discharge rate of the SA is considerably faster than the natural self-excitatory discharge rate of either the A-V node or the Purkinje fibers

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13
Q

Abnormal Pace makers are also reffered to as?

A

Ectopic pacemaker

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14
Q

Isovolumetric contraction of the ventricles correspond to what segment of the ECG

A

RS segment ( of QRS)

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15
Q

Isovolumetric Relaxation of the ventricles correspond to what segment of the ECG

A

End of T-wave ( Ventricular re-polarization)

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16
Q

Ejection of ventricular volume correspond to what segment of the ECG

A

Begins at the S-wave and stops near the of the of the T-wave

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17
Q

What happens during systole

A

Begins with R-wave peak: Isovol- contraction (inc press)
AV-valves closes
ST- segment: Ejection (increase pressure, dec vol) : Pressure build up opens Aortic valves
Isovolumetric relaxation: End of T wave - (dec presure)
AV valves open

18
Q

Diastole is represented by the end of the _ wave and the ___ of the __ wave

A

end of t-wave

peak of R-wave

19
Q

What are the events happening ventricles diastole

A

Rapid filling AV valves open
Ventricular re-polarization
Increase in ventricular volume

20
Q

Arteriole systole happens when and why?

A

Near the of ventricular diastole, act as primer pumps

  • > Mid P-wave to peak of R-wave
  • > also know as period of slow filling
21
Q

Why does the SA node control the heart?

A

The discharge rate of the sinus node is considerably faster than the natural self-excitatory discharge rate of either the A-V node or the Purkinje fibers.

22
Q

What would happen if there was no delay of AP in AV node?

A

The atria would not be able to empty into the ventricles before they contract,
-> Decrease SV and CO

23
Q

After the AP spreads through the Purkinje fibers what does it stimulate before it stimulates the entire ventricles?

A

The Papillary muscles.

Prevent inversion or prolapse of these valves on systole

24
Q

What cause the conduction of AP to slow down as it passes through the AV bundle to

A

Diminished number of Gap Junction w/ each successive cells

25
Q

_____ portion of the A-V bundle passes downward in the ventricular septum for 5 to 15 millimeters toward the apex of the heart

A

Distal

26
Q

Special _____ fibers lead from the A-V node through the A-V bundle into the ventricles

A

Purkinje

27
Q

At the termination of the _______, the impulse rapidly travels through the ventricle muscle fibers via ______, from the inside (endocardium) to the outside (epicardium)

A

Purkinje fibres

Gap Junctions

28
Q

What is the importance of the rapid propagation of the cardiac impulse through the Purkinje fibres and ventricles

A

Provides an effective contraction

29
Q

Phases of ventricular action potential ( 5 phases)

A

Phase 4: resting membrane potential near the K+ equilibrium potential.
Phase 0: depolarizing impulse activates fast Na+ channels and inactivates K+ channels.
Phase 1: Transient opening of K+ channels and Na+ channels begin to close.
Phase 2: Ca2+ channels are open, key difference compared to nerve AP.
Phase 3: repolarization, Ca2+ inactivate and K+ channels open.
Refractory period: Na+ channels are inactive until membrane is repolarized

30
Q

What effects does the fact that the refractory period is very long in cardiac muscle in conmprisent with sktl muscle

A

Cardiac muscle CAN NOT sum action potentials or contractions and CAN NOT be tetanized where as sketl muscle can

31
Q

What happens if there is a block in AV-bundle

A

after a few seconds the purkynji fibers become an ectopic pacemakeer

32
Q

Parasympathetic changes of Hr rhythm

A

Releases acetylcholine

Decreases heart rhythm and excitability.

Excitatory signals are no longer transmitted into the ventricles.

Ventricular Escape

Increased permeability of the fiber membranes to potassium ions

33
Q

Sympathetic changes to Heart Rhythm

A

Releases norepinephrine at sympathetic endings.

Increases the rate of sinus nodal discharge.

Increases the overall heart activity.

Increases the permeability of Na+ and Ca2+ ions.

34
Q

Parasympathetic stimulation would effect the ecg in which sense?

A

Longer time during end of T-wave and Peak of next R- wave

-> decreasing HR

35
Q

Parasympathetic stimulation would effect the vol/press curve in which sense?

A

Increase period of filling

36
Q

Sympathetic stimulation would effect the ecg curve in which sense

A

Shoter time b/t each R-wave

-> increasing HR

37
Q

Sympathetic stimulation would effect the vol/press curve in which sense

A

-Decreased time of ventricular filling

38
Q

Autonomic nervous system modulates the _____ of depolarization of pacemaker

A

Frequency

39
Q

Sympathetic stimulation (neurotransmitter = ______); binds to ____receptors on the __ nodal membranes

A

norepinephrine
beta1
SA

40
Q

Parasympathetic stimulation (neurotransmitter = ____); binds to ____ receptors on nodal membranes; increases conductivity of __ and decreases conductivity of ___

A

acetylcholine
muscarinic
K+
Ca2+

41
Q

What does a larger than normal R-wave deflection represent?

What are some Possible causes?

A

Ventricles are contracting hard than normal.

  • > High systemic resistance
  • > Aortic valve dysfunction
  • > Ventricular Hypertrophy (?)
42
Q

What does the Peak of the R-wave signify?

A

Beginning of systole

EXCI 357 Physiology 2 (5 decks)

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