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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
What does aortic pressure reflect pathophysiologically?
The ejection of blood from the LV | Rises as elastic fibers stretch as blood is ejected at the onset of systole
26
What maintains aortic pressure during diastole?
Recoil of the elastic fibers in the aorta
27
Incisura
Notch, in aortic pressure, represents valve closure due to back flow of blood immediately before closure of the valve
28
Rapid filling period
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
29
End-diastolic volume
The volume that fills into the ventricle during diastole
30
End-systolic volume
The amount of blood that remains in the ventricles
31
Ejection fraction
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
32
What might impact right atrial pressure?
Decreased when heart pumps strongly, enhancing atrial filling Decreased during inspiration increased during coughing or forced expiration
33
Venous return
Amount of blood in the systemic circulation returning tot he right heart and the force that moves blood back to the right heart
34
When is venous return high?
When blood volume increases or the pressure of the right atrium falls
35
When is venous return low?
hypovolemic shock When right atrial pressure rises
36
When is diastolic filling decreased? How does the body compensate?
Increased heart rate or heart disease Compensate: right atria can contribute as much as 20% of cardiac reserve
37
Cardiac output
The efficiency of the heart; amount of blood pumped eat minute CO= SV X HR
38
Cardiac Reserve
The maximum percentage of increase in CO above normal resting level Eg: average is 300%-400%
39
What factors impact the heart’s ability to increase output?
reload or ventricular filling, afternoon or resistance to ejection of blood from the heart, cardiac contractility, and HR
40
Preload
End-diastolic pressure hen ventricle has been filled Load imposed prior to contraction; amount of blood the heart pumps per beat
41
Frank-Starling Mechnaims
Increased force of contraction that accompanies increased ventricular end-diastolic volume Allows heart to accommodate various levels of venous return
42
After load
Work postcontraction required to move blood into the aorta Eg: systemic arterial pressure, pulmonary arterial pressure
43
When is left ventricular afterload increased?
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
Cardiac contractility
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
Inotropic influence
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
What does HR determine?
Frequency of blood ejection from the heart
47
Impact of HR on CO
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
Pulmonary circulation
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
Systemic circulation
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
Inferior vena cava
Veins from the low body merge to form this Empty into right heart
51
Superior vena cava
Veins from head and upper extremities merge to form this empty into right heart
52
How does the body accommodate for beat by beat variations in CO?
Storage capabilities of the venous system
53
When might blood accumulation in the heart?
When storage capacity of the venous system is exceeded
54
Arterioles
Resistance vessels that provide most of the resistance to circulatory flow Contain layer of smooth muscle that encloses vessel walls
55
Capillaries
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
Venules and veins
Thin-walled, high compliance vessels that function as a reservoir to collect blood and return it to the right heart
57
Impact of parallel arrangement of vessels
Resistance of blood flow will be low, allowing each tissue to regulate its own blood flow
58
Impact of viscosity on flow | what might increase viscosity?
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
Factors that impact the hemodynamics of blood flow
Pressure, resistance, vessel radius, cross-sectional area, velocity of flow, laminar, turbulent flow
60
Turbulent flow (what is happening with the blood)
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
Laminar flow
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
What might cause turbulent flow?
High velocity of flow, change in diameter, obstruction, low blood viscosity
63
What type of tension would a thicker vessel wall exhibit?
Lower tension Eg: in hypertension, arterial vessel walls hypertrophy develops and become thicker, reducing the tension and minimizing wall stress
64
What vessels control blood pressure?
Walls of the arterioles Smooth muscle
65
Consequences of less sarcoplasmic reticular in smooth muscles
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
Why do calcium-channel blocking drugs cause vasodilation?
They block calcium entry through the calcium channels
67
what else can impact smooth muscle contraction and relaxation?
lack of oxygen, increase in hydrogen ion concentration, excess carbon dioxide, nitric oxide (smooth muscle relaxation and blood flow regulation)
68
What does the elasticity of arteries allow them to do?
Stretch during systole and recoil during diastole
69
Why do injuries pulsate?
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
Venous muscle pump
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
Autoregulation
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
Reactive hypermedia
An increase in local blood flow following a brief period of ischemia
73
Functional hyperemia
An increase in blood flow with increased activity (eg: exercise)
74
Action of NO
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
Shear stress
On the endothelium from increased blood flow or blood pressure stimulates NO production and vessel realxation
76
Nitroglycerin
Used in the treatment of angina by causing release of NO in vascular smooth muscle of the target tissues
77
Long-term regulation of blood flow
Angiogenesis (growth factors) Oxygen levels Collateral circulation (anatomical channels increase in size when arteries are occluded)
78
Humoral controllers of vascular function
``` Norepinephrine Epinephrine Angiotensin II Histamine Serotonin Bradykinin Prostaglandins ```
79
Norepinephrine and epinephrine
Vasoconstrictors Epi (sometimes vasodilator)
80
Angiotensin II
Vasoconstrictor, part of the RAAS system Acts on arterioles to increase PVR and furthermore, increase blood pressure
81
Histamine
Vasodilator effect on arterioles Increases capillary permeability —> allows leakage of fluid and plasma proteins into tissues
82
Serotonin
Taken from aggregating platelets during clotting Causes vasoconstriction Plays a major role in bleeding
83
Bradykinin
Causes intense dilation of arterioles, increased capillary permeability, and contraction of venules
84
Micro circulation
The functions of the smallest blood vessels, the capillaries, and lymphatic vessels, which transport nutrients to tissues and remove waste from cells
85
Capillary pores
Water-filled junctions that join capillary endothelial cell and provide a path for passage of substances
86
Fenestrations
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
How are gases and fluids exchanged across the capillary wall?
Via discussion water flows through aqua portions
88
Nutrient flow
Blood flow through capillary channels designed for exchange of nutrients and metabolites
89
Non-nutrient flow
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
Filtration
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
Absorption
Net movement from the interstitial into the capillary
92
Function of lymphatic system
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
Lymph
Contains plasma proteins and other osmotically active particles that rely on the lymphatic for movement back into the circulatory system
94
What occurs when lymph flow is obstructed?
Lymphedema occurs
95
Area of Brian that controls integration and modulation of cardiac function and blood pressure
Medulla oblongata Vasomotor center: control sympathetic mediated acceleration of HR and blood vessel tone Cardioinhibitory center: controls parasympathetic mediated slowing of HR
96
What provide the medullary cardiovascular center with continuous information regarding changed in BP?
Arterial baroreceptors and chemoreceptors
97
Parasympathetic innervation of the heart
Vagus nerve stimulation leads to changes in HR - Increased activity slows pulse through release of acetylcholine -
98
When do vasomotor neurons of the CNS become excited?
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
Cushing Reaction
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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