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Semester 1 > Patho Exam 5 > Flashcards

Patho Exam 5 Flashcards

1
Q

What are the three junctions of the intercalated disks and their functions

A
  1. Desmosomes - AKA Macula Adherens, They prevent separation during contractions
  2. Fascia Adherens - the anchoring sites for actin and they mechanically attach one myocyte to another
  3. Gap Junctions - Allow the AP to spread by permitting ions to pass from one myocyte to another
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2
Q

What is the function of a T tubule?

A
  • Allows faster access of ions to myofibrils
  • Transmission of AP’s from the sarcolemma to the myofibrils
  • AP stimulation releases Ca from the SR
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3
Q

What is an A band

A

Also called the anisotropic band. Is the dark band on myocardial cells. It is composed of the thick filaments of myosin.

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4
Q

What is the I band

A

The light bands comprised of thin filaments of actin which extend from the Z line

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5
Q

What is located in the H zone?

A

A single Tropomyosin relaxing protein and 7 actin filaments

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6
Q

What are the three phases of ventricular activation in order?

A
  1. Septal
  2. Apical
  3. Basal and posterior
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7
Q

Facts about the LAFB

A
  • passes the left anterior papillary muscle
  • crosses the aortic outflow tract
  • Damage to the LV or Aortic valve an impact it
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8
Q

Facts about the LPFB

A
  • Well protected from damage because blood flow is not turbulent here
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9
Q

Why does the SA node have automaticity?

A

Slow leaky Ca channels cause it to not have a stable resting membrane potential. -60 mv

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10
Q

What are the phases of cardiac depolarization in order?

A

Phase 0-4

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11
Q

What occurs in Phase 0?

A

Depolarization. Threshold is reached in the SA. Na VG channels open and rushes into the cell

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12
Q

What occurs in Phase 1?

A

Early repolarization.VG Na channels rapidly shut. VG Ca channels open.

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13
Q

What occurs in phase 2?

A

Plateau phase. Rapid reversal in membrane polarity to -15 mv. Slow influx of Ca balances out Efflux of K

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14
Q

What occurs in phase 3?

A

Rapid repolarization. VG K channels open and K exits the cell. Return to resting membrane potential

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15
Q

What occurs in Phase 4?

A

Resting membrane potential. -80 to -90 mv. The time between AP’s

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16
Q

What are the A bands composed of?

A

Thick filaments of myosin.

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17
Q

What are the I bands composed of?

A

Thin filament of actin

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18
Q

What is the function of Troponin I?

A

Inhibits the ATPase of actomyosin. It prevents the breakdown of ATP into ADP and Pi. Thus it inhibits myosin cross bridging

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19
Q

What is the function of Troponin T?

A

It binds tropomyosin to Aictin

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20
Q

What is the function of Troponin C?

A

It has the Ca receptor

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21
Q

What are considered the relaxation proteins?

A
  • Troponin
  • Tropomyosin
    because they cover the actin binding site.
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22
Q

Where is Ca stored in the cardiac cells

A

In the Sarcoplasmic Reticulum

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23
Q

What are the two types of Ca channels?

A
  • L Type are the predominant type which are long lasting and affected by Ca Channel Blockers
  • T Type are transient and are much less common. They are not affected by any Ca Channel Blockers
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24
Q

What changes occur when Ca binds to troponin

A

Ca binding inhibits Troponinc C which when resting enhances Troponin I to cover actin. This leads to the uncovering of the actin sites.

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25
Q

Resting membrane potentials for SA Node, AV Node and Myocardial cells

A
  • SA -50 to -60 mv
  • AV -60 to -70 mv
  • Myocardial Cell -80 to -90 mv
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26
Q

Why can tetany not occur in cardiac tissue

A

Because the RRR is nearly as long as the AP.

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27
Q

Can cardiac tissue be summated?

A

No

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28
Q

What are the 5 phases of the cardiac cycle?

A

Phase 1 atrial systole
Phase 2 Isovolumetric ventricular contraction
Phase 3 Ventricular Ejection
Phase 4 Isovolumetric ventricular relaxation
Phase 5 Passive ventricular filling

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29
Q

What makes the first heart sound?

A

It is the closing of the AV valves. Produced immediately after the QRS is observed.

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30
Q

What causes the second heart sound?

A

The closing of the semilunar valves. Produced just after the T wave is observed.

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31
Q

What causes the third heard sound?

A

It is tension being applied to the chordae tendineae during rapid ventricular filling. Normaly heard in children and some athletes

32
Q

What causes the fourth heart sound?

A

It is a pathologic sign caused by blood being forced into a stiff/ hypertrophic ventricle

33
Q

What are the waves on an atrial pressure graph?

A
  • A wave is atrial contraction
  • X descent wave is Atrial diastole
  • V wave is atrial filling
  • Y descent wave is blood from the veins and atrium into the RV
  • C wave is the bulging of the mitral valve into the LA
34
Q

Which parts of the heart are innervated by the SNS?

A

All parts of the A and V

35
Q

What parts of the heart are innervated by the PNS?

A

All parts of the A and V along with the SA and AV nodes.

36
Q

Where are cardiac B1 receptors found?

A
  • SA node
  • AV node
  • Purkinje fibers
  • Atrial and Ventricular myocardium
37
Q

Where are cardiac B2 receptors found?

A

Mostly in the coronary arteries.

38
Q

Effects of cardiac adrenergic receptor activation

A

A1 - NE Coronary artery constriction
A2 - NE Inhibition of NE release leading to vasodilation
B1 - NE Increase HR and contractility
B2 - Epi Coronary artery dilation

39
Q

Which dominates SNS or Vagal stimulation?

A

Vagal

40
Q

What is the optimal sarcomere length when referring to the Frank - Starling Law?

A

2.2 - 2.4 mm

41
Q

What happens if the sarcomere is stretched beyond 2.2 - 2.4 mm?

A

The force of contraction declines because actin and myosin are partially disengaged

42
Q

What happens if the sarcomere is stretched beyond 3.65 mm?

A

Actin and myosin become completely disengaged and contractile force drops to zero.

43
Q

Why does the strength of contraction vary directly with EDV?

A

Frank- Starling Law

44
Q

Define preload?

A

The workload on the heart prior to contraction. AKA EDV.

45
Q

What can occur from increased LVEDV?

A

Increased pulmonary pressure, forcing plasma through the vessel walls which created pulmonary edema.

46
Q

Define afterload?

A

The load which the ventricle must move in order to eject blood. Think Aortic pressure

47
Q

What does Laplace’s Law state?

A

The amount of tension needed to produce a pressure is dependent on the size of the vessel

48
Q

What 3 variables regulate SV?

A
  • EDV
  • TPR
  • Contractility (which is related to Ca)
49
Q

What two mechanisms of the Medulla can decrease HR?

A
  1. Inhibition of Sympathetic stimulation of the SA node

2. Activation of parasympathetic stimulation of the SA node

50
Q

Which condition of aging is associated with a dysfunctional baroreceptor reflex?

A

Orthostatic hypotension

51
Q

What is the Bainbridge reflex?

A

In increase in HR after an IV infusion.

52
Q

What is the normal EF?

A

60-75%

53
Q

Examples of Positive Inotropic Agents

A
  • Excess Thyroid Hormone
  • NE
  • Calcium Salt infusion
54
Q

Examples of Negative Inotropic Agents

A
  • ETOH

- Propranolol

55
Q

What is the equation for blood flow?

A

Q= Pressure difference/R

Blood Flow = P1 - P2/ TPR

56
Q

Where are Baroreceptors located?

A
  • Atria
  • Aorta
  • Carotid Sinus
57
Q

Where are chemo receptors located and what do they do?

A

Located throughout the body and they stimulate respiration after a drop in SpO2

58
Q

Define vascular compliance

A

Increase in the volume of a vessel to accommodate for a given pressure.

59
Q

Define MAP

A

The average arterial pressure during the cardiac cycle

60
Q

What is the equation for MAP?

A

Diastolic pressure + 1/3 pulse pressure

61
Q

What is the equation form pulse pressure?

A

Systolic - Diastolic

62
Q

When is ADH released? and what does it do?

A

ADH is released when osmoreceptors detect an increase in plasma osmolality. It produces thirst sensation and stimulates H2O reabsorbtion

63
Q

Where are the osmoreceptors located

A

In the hypothalamus

64
Q

What factor stimulate the release of Renin?

A
  • Drop in renal artery BP
  • Decrease in Na and Cl delivered to the kidney
  • Stimulation of B1 and B2
  • Angiotensin II
  • Low K
65
Q

What does the AT1 angiotensin receptor do?

A

Proinflammatory effects such as myocyte hypertrophy and vasocinstriction

66
Q

What does the AT2 angiotensin receptor do?

A

Counterregulatory mechanism such as Mediates vasodilation by the natriuretic cascade

67
Q

What stimulates the release of ANP and BNP? What do they do?

A

Stretching of the atria release them. They increase Na and H2O excretion. They are antagonists of Aldosterone and Angiotensin II

68
Q

Where is urodilatin produced and what is it’s function?

A

Produced in the kidney and it increased Na and H2O excretion.

69
Q

What is Adrenomedulin and what is its function?

A

ADM it is secreted from the vascular endothelium and smooth muscle cells. It is a vasodilator

70
Q

What paracrine regulators/vasodilators are secreted by the vascular endothelium?

A
  • NO
  • Bradykinin
  • Prostaglandin
  • Endothelin-1
71
Q

How is NO produced?

A

Arterioles contain eNOS which produce NO

72
Q

MOA of NO

A

It diffuses into the smooth muscle of the vessel. Here it activates guanylate cyclase thus cGMP and lowers cytoplasmic Ca

73
Q

What is the systolic compressive effect?

A
  • Aortic valve cusps obstruct the coronary bloodflow during systole
  • Coronary vessles constrict during systole
74
Q

Define coronary perfusion pressure?

A

The difference between the pressure in the Aorta and the pressure in the coronary vessel of the RA

75
Q

Most coronary blood flow occurs duing which cycle?

A

Diastole

76
Q

An increase of adenosine K or Co2 will do what to blood vessles?

A

Vasodilate

77
Q

A decrease of O2 or pH will do what to blood vessles?

A

Vasodilate

Semester 1 (15 decks)

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