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Pathophysiology > Chapter 25 > Flashcards

Chapter 25 Flashcards

1
Q

Main function of circulatory system

A

Transport of oxygen and nutrients needed for metabolic processes to the tissues

Transport of waste from tissues to kidneys and other excretory organs

Circulates electrolyte and hormones needed for body function regulation

Transports core heat to periphery to regulate body temp

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2
Q

Heart location

A

Mediastinal space of intrathoracic cavity

Sits within the pericardium

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3
Q

Pericardium

A

Loose sac that surrounds and protects the heart (physically and from infection)

Holds it in fixed position, prevents acute dilation of chambers

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4
Q

Point of maximum impulse

A

Felt against the chest wall between the fifth and sixth ribs, below nipple, MCL

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5
Q

Wall of heart

A

Epicardium
Myocardium
Endocardium

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6
Q

Epicardium

A

Lines the pericardial cavity (potential space containing 30-50 mL of serous fluid to minimize friction as the heart contracts and relaxes against surrounding structure)

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7
Q

Myocardium

A

Muscle layer, forms wall of atria and ventricles

Muscle cells or vide the energy needed for the heart to pump continuously

Atria contract prior to the ventricles, which is required for proper heart function

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8
Q

Endocardium

A

Lines the chambers of the heart (3 layers)

Inner: smooth endothelial cells (consistent with the lining of the blood vessels that enter the heart), thin layer of connective tissue

Middle: dense connective tissue with elastic fibers

Outer: irregularly arranged connective tissue cells, continuous with myocardium, contains blood vessels and branches of the conduction system

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9
Q

What lab measurement is used to diagnose MI?

A

Measurement of serum levels of the cardiac forms of troponin T and toponin I

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10
Q

Impact of less well-defined sarcophagi can reticulum in cardiac cells

A

Less ability to store calcium than skeletal muscles cells

This, rely heavily on an influx of extra cellular calcium ions for contraction

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11
Q

Atrioventricular valves (AV)

A

Prevent back flow of blood from the ventricles during systole when closed

Valve edges form cusps

  • Two on left side of heart (bicuspid or mitral)
  • Three on right side (tricuspid valve)
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12
Q

Semilunar valves (aortic and pulmonic valves)

A

Prevent back flow from the aorta and pulmonic arteries into the ventricles during diastole

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13
Q

Pulmonic Valve

A

Located between the right ventricle and the pulmonary artery

Control the flow of blood into the pulmonary circulation

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14
Q

Aortic valve

A

Located between the left ventricle and the aorta

Controls the flow of blood into the systemic circulation

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15
Q

Are there valves at the atrial sites where blood enters the heart?

A

No

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16
Q

What happens if the atria become distended?

A

Blood will be pushed back into the veins

Eg: jugular veins become prominent in severe right-sided heart failure

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17
Q

Cardiac Cycle

A

Rhythmic pumping action of the heart
1- Systole
2- Diastole

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18
Q

Systole

A

The period during which the ventricles are contracting

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19
Q

Diastole

A

The period during which the ventricles relax and fill with blood

4th heart sound: heard during last third of diastole as atria contract

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20
Q

Does the mechanical movement or electrical activity of the heart begin first?

A

Electrical activity is always first

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21
Q

P wave

A

Depolarization of the sinoatrial (SA) node, atrial conduction tissue, and atrial muscle mass

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22
Q

QRS complex

A

Depolarization of the ventricular conduction system and ventricular muscle mass

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23
Q

T wave

A

Occurs during the last half of systole

Represents depolarization of the ventricle

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24
Q

Describe what is going on pathophysiologically in S1 and S2.

A

Isovolumentric contraction —> closure of AV valves and first heart sound (S1) —> onset of systole —> semilunar valves remain closed for 0.02-0.03. Seconds —> ventricular pressure rise abruptly —> contraction of ventricles —> left ventricular pressure and right ventricular pressure are higher than pulmonary artery pressure —> semilunar valves open —> ejection period —> 60% SV ejected during first quarter of systole —> 40% ejecting during next two quarters of systole —> ventricles remain contracted last quarter of systole —> ventricle relax —> intraventricular pressure decreases —> blood flow back toward ventricles originating from larger arteries —> aortic and pulmonic valves to snap shut, creating the second heart sound (S2)

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25
Q

What does aortic pressure reflect pathophysiologically?

A

The ejection of blood from the LV

Rises as elastic fibers stretch as blood is ejected at the onset of systole

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26
Q

What maintains aortic pressure during diastole?

A

Recoil of the elastic fibers in the aorta

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27
Q

Incisura

A

Notch, in aortic pressure, represents valve closure due to back flow of blood immediately before closure of the valve

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28
Q

Rapid filling period

A

During diastole, when most of ventricular filling occurs; during first 1/3 of diastole

3rd heart sound: heard during rapid filling period as blood flows into a distended or non compliant ventricle

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29
Q

End-diastolic volume

A

The volume that fills into the ventricle during diastole

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30
Q

End-systolic volume

A

The amount of blood that remains in the ventricles

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31
Q

Ejection fraction

A

Percentage of end-diastolic volume ejected during systole

Typically around 55-75 percent

May be used to evaluate prognosis of those with various heart diseases

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32
Q

What might impact right atrial pressure?

A

Decreased when heart pumps strongly, enhancing atrial filling

Decreased during inspiration

increased during coughing or forced expiration

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33
Q

Venous return

A

Amount of blood in the systemic circulation returning tot he right heart and the force that moves blood back to the right heart

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34
Q

When is venous return high?

A

When blood volume increases or the pressure of the right atrium falls

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35
Q

When is venous return low?

A

hypovolemic shock

When right atrial pressure rises

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36
Q

When is diastolic filling decreased? How does the body compensate?

A

Increased heart rate or heart disease

Compensate: right atria can contribute as much as 20% of cardiac reserve

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37
Q

Cardiac output

A

The efficiency of the heart; amount of blood pumped eat minute

CO= SV X HR

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38
Q

Cardiac Reserve

A

The maximum percentage of increase in CO above normal resting level

Eg: average is 300%-400%

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39
Q

What factors impact the heart’s ability to increase output?

A

reload or ventricular filling, afternoon or resistance to ejection of blood from the heart, cardiac contractility, and HR

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40
Q

Preload

A

End-diastolic pressure hen ventricle has been filled

Load imposed prior to contraction; amount of blood the heart pumps per beat

41
Q

Frank-Starling Mechnaims

A

Increased force of contraction that accompanies increased ventricular end-diastolic volume

Allows heart to accommodate various levels of venous return

42
Q

After load

A

Work postcontraction required to move blood into the aorta

Eg: systemic arterial pressure, pulmonary arterial pressure

43
Q

When is left ventricular afterload increased?

A

With narrowing (stenosis) of the aortic valve

The left ventricle may need systolic pressures up to 300 mmHg to move blood through the narrowed valve

44
Q

Cardiac contractility

A

Ability of the heart to change its force of contraction without changing its resting (diastolic) length

Strongly influenced by the number of calcium ions available

45
Q

Inotropic influence

A

Modifies the contractile state of the heart independent of the Frank-starling mechanism

Eg: hypoxia exerts a negative inotropic effect by interfering with the generation of ATP that is needed for muscle contraction

46
Q

What does HR determine?

A

Frequency of blood ejection from the heart

47
Q

Impact of HR on CO

A

As HR increases, Co increase

As HR increases, time spent in systole is the same, but time spent in diastole is reduced —> less time to fill ventricles —> decreased sV —> decreased CO at very high tachycardia rates —> heart cannot fill adequately

48
Q

Pulmonary circulation

A

Moves blood through the lungs for gas exchange

Organs: right heart, pulmonary artery, pulmonary capillaries, pulmonary veins

Action: low pressure and low resistance circuit moving blood to and from the lungs (eg: blood moves slowly —> important for gas exchange)

49
Q

Systemic circulation

A

Supplies all the other tissues of the body with oxygen

Organs: left heart, aorta, branches, capillaries (supply brain and peripheral tissues), systemic venous system, vena cava

Action: high pressure system due to substantial resistance to blood flow due to effects of gravity

50
Q

Inferior vena cava

A

Veins from the low body merge to form this

Empty into right heart

51
Q

Superior vena cava

A

Veins from head and upper extremities merge to form this

empty into right heart

52
Q

How does the body accommodate for beat by beat variations in CO?

A

Storage capabilities of the venous system

53
Q

When might blood accumulation in the heart?

A

When storage capacity of the venous system is exceeded

54
Q

Arterioles

A

Resistance vessels that provide most of the resistance to circulatory flow

Contain layer of smooth muscle that encloses vessel walls

55
Q

Capillaries

A

Small, thin-walled vessels that link arterial and venous circulation

Allow for exchange of oxygen and tissue metabolites

Contain the smallest amount of blood

56
Q

Venules and veins

A

Thin-walled, high compliance vessels that function as a reservoir to collect blood and return it to the right heart

57
Q

Impact of parallel arrangement of vessels

A

Resistance of blood flow will be low, allowing each tissue to regulate its own blood flow

58
Q

Impact of viscosity on flow

what might increase viscosity?

A

Resistance to flow caused by the friction of molecules in a fluid

If hematocrit increases, viscosity increases
If temperature increases by 1 degree Celsius, so does viscosity by 2%

59
Q

Factors that impact the hemodynamics of blood flow

A

Pressure, resistance, vessel radius, cross-sectional area, velocity of flow, laminar, turbulent flow

60
Q

Turbulent flow (what is happening with the blood)

A

Blood element developed vortices that push blood cells and platelets against the vessel wall —> more pressure needed to move blood through the vessel or valve

Can result from increased velocity of flow, decreased vessel diameter, or low blood viscosity

Usually accompanied by vibrations of the fluid and surrounding structures (can be detected as murmurs or bruits)

61
Q

Laminar flow

A

Blood components are arranged so that plasma is adjacent to the endothelial surface of the blood vessel and the blood elements are in the center of the blood stream

62
Q

What might cause turbulent flow?

A

High velocity of flow, change in diameter, obstruction, low blood viscosity

63
Q

What type of tension would a thicker vessel wall exhibit?

A

Lower tension

Eg: in hypertension, arterial vessel walls hypertrophy develops and become thicker, reducing the tension and minimizing wall stress

64
Q

What vessels control blood pressure?

A

Walls of the arterioles

Smooth muscle

65
Q

Consequences of less sarcoplasmic reticular in smooth muscles

A

Less ability to store intracellular calcium; fewer fast sodium channels

Depolarization of smooth muscle relies largely on extra cellular calcium which tinkerers through calcium changes in the muscle membrane

66
Q

Why do calcium-channel blocking drugs cause vasodilation?

A

They block calcium entry through the calcium channels

67
Q

what else can impact smooth muscle contraction and relaxation?

A

lack of oxygen, increase in hydrogen ion concentration, excess carbon dioxide, nitric oxide (smooth muscle relaxation and blood flow regulation)

68
Q

What does the elasticity of arteries allow them to do?

A

Stretch during systole and recoil during diastole

69
Q

Why do injuries pulsate?

A

When the pressure pulse is abnormally transmitted to small vessels, like capillaries due to extreme dial action of small vessels in the injured areas

may also occur in conditions that cause exaggeration of aortic pressure pulses (eg: aortic regurgitation or patent ductus arteriosus)

70
Q

Venous muscle pump

A

Skeletal muscles that surround and compress leg veins to move blood to the heart though one-way valves

Control pressures of the lower extremities

71
Q

Autoregulation

A

The ability to maintain constant change in perfusion pressure mediated by changes in vessel tone resulting from changes in flow or by local tissue fact (eg: lack of oxygen or accumulation of metabolites)

72
Q

Reactive hypermedia

A

An increase in local blood flow following a brief period of ischemia

73
Q

Functional hyperemia

A

An increase in blood flow with increased activity (eg: exercise)

74
Q

Action of NO

A

Relaxes vascular smooth muscle

Stimulated by a variety of endothelial agonist (acetylcholine, bradykinin, histamine, thrombin)

Inhibits platelet aggregation and secretion of platelet contents that would lead to vasoconstriction

Protects against thrombosis and vasoconstriction

75
Q

Shear stress

A

On the endothelium from increased blood flow or blood pressure stimulates NO production and vessel realxation

76
Q

Nitroglycerin

A

Used in the treatment of angina by causing release of NO in vascular smooth muscle of the target tissues

77
Q

Long-term regulation of blood flow

A

Angiogenesis (growth factors)

Oxygen levels

Collateral circulation (anatomical channels increase in size when arteries are occluded)

78
Q

Humoral controllers of vascular function

A 
Norepinephrine
Epinephrine
Angiotensin II
Histamine
Serotonin
Bradykinin
Prostaglandins
79
Q

Norepinephrine and epinephrine

A

Vasoconstrictors

Epi (sometimes vasodilator)

80
Q

Angiotensin II

A

Vasoconstrictor, part of the RAAS system

Acts on arterioles to increase PVR and furthermore, increase blood pressure

81
Q

Histamine

A

Vasodilator effect on arterioles

Increases capillary permeability —> allows leakage of fluid and plasma proteins into tissues

82
Q

Serotonin

A

Taken from aggregating platelets during clotting

Causes vasoconstriction

Plays a major role in bleeding

83
Q

Bradykinin

A

Causes intense dilation of arterioles, increased capillary permeability, and contraction of venules

84
Q

Micro circulation

A

The functions of the smallest blood vessels, the capillaries, and lymphatic vessels, which transport nutrients to tissues and remove waste from cells

85
Q

Capillary pores

A

Water-filled junctions that join capillary endothelial cell and provide a path for passage of substances

86
Q

Fenestrations

A

Present in glomerular capillaries in the kidneys

Small openings that pass through the middle of endothelial cells —> allow large amounts of small molecules and ionic substances to filter through the glomeruli without having to pass through the clefts between the endothelial cells

87
Q

How are gases and fluids exchanged across the capillary wall?

A

Via discussion

water flows through aqua portions

88
Q

Nutrient flow

A

Blood flow through capillary channels designed for exchange of nutrients and metabolites

89
Q

Non-nutrient flow

A

When blood flow bypasses the capillary bed, moving through an arterioles out shunt directly from an arterioles to a venules

Does not allow for nutrient exchange (most common in the skin, important for heat exchange and temperature regulation)

90
Q

Filtration

A

Net fluid movement out of the capillary into the interstitial spaces

Most reabsorbed at the venous end of the capillary

Capillary hydrostatic pressure is the force in capillary filtration determined by venous and arterial pressures

91
Q

Absorption

A

Net movement from the interstitial into the capillary

92
Q

Function of lymphatic system

A

Removes excess fluid, osmotically active proteins, and large particles from the interstitial space and returns them to circulation

Main rout for absorption of nutrients, particularly fats, from the GI tract

Filters the fluid at lymph nodes and removes foreign particles such as bacteria

93
Q

Lymph

A

Contains plasma proteins and other osmotically active particles that rely on the lymphatic for movement back into the circulatory system

94
Q

What occurs when lymph flow is obstructed?

A

Lymphedema occurs

95
Q

Area of Brian that controls integration and modulation of cardiac function and blood pressure

A

Medulla oblongata

Vasomotor center: control sympathetic mediated acceleration of HR and blood vessel tone

Cardioinhibitory center: controls parasympathetic mediated slowing of HR

96
Q

What provide the medullary cardiovascular center with continuous information regarding changed in BP?

A

Arterial baroreceptors and chemoreceptors

97
Q

Parasympathetic innervation of the heart

A

Vagus nerve

stimulation leads to changes in HR
- Increased activity slows pulse through release of acetylcholine
-

98
Q

When do vasomotor neurons of the CNS become excited?

A

From interruption of blood flow to the brain that causes ischemia of the vasomotor center —> vasoconstriction —> increased BP to as high as the heart can pump against (CNS ischemic response)

Will not occur until BP falls to at least 60 mmHG, but can only sustain for 3-10 minutes —> if cerebral circulation is not reestablished, the neurons of the vasomotor center cease to function —> tonic impulses of blood vessels stop and BP fall quickly

99
Q

Cushing Reaction

A

CNS response from increase in intracranial pressure

Increase in intracranial pressure —> blood vessel of vasomotor center compress —> initiate CNS ischemic response —> rise in arterial pressure above intracranial pressure —> reestablished blood flow to vasomotor center

Accommodation is usual in short duration and helps protect vital centers of the brain from nutrition loss if the CNS fluid rises high enough to compress the cerebral arteries

If pressure were to rise to a point that blood supply to the vasomotor center becomes inadequate, vasoconstrictor tone is lost, BP begins to fall
Increase intracranial pressure crushes blood vessel that supply the brain

Pathophysiology (9 decks)

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