Cardiovascular 1 Flashcards

Blood pressure and volume.

1
Q

Total Peripheral Resistance is determined by the…

A

degree of vasoconstriction, primarily in the arterioles.

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2
Q

Mean Arterial Pressure is primarily due to:

A

Blood Volume

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3
Q

If BP is too high, renal mechanisms will generally…

A

INCREASE fluid loss in urine

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4
Q

If BP is too low, mechanisms will…

A

RETAIN Na+ and H2O & INCREASE thirst

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5
Q

Normal MAP is approximately:

A

100 mmHg

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6
Q

Normal HR is approximately:

A

72 bpm

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7
Q

Normal SV is approximately:

A

70 mL

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8
Q

Normal CO is approximately:

A

5 L/min

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9
Q

SNS activity ____ HR

A

INCREASES

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10
Q

Parasympathetic activity ___ HR

A

DECREASES

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11
Q

At rest, ______ nerve input predominates.

A

Parasympathetic

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12
Q

In the heart, ____ is the preload (amt a muscle must stretch before contraction)

A

EDV

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13
Q

In the heart, ____ is the afterload (force a muscle contracts against)

A

Arterial BP

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14
Q

Frank-Starling Mechanism

A

Increasing EDV increases SV

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15
Q

In hemorrhagic shock, the Frank-Starling Mechanism ensures:

A

Reduced blood volume leads to reduces CO

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16
Q

In heart failure, the Frank-Starling Mechanism ensures:

A

Increased blood volume leads to increased CO (initially)

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17
Q

The Frank-Starling Mechanism is due to:

A

More muscle cell stretching allows more actin-myosin cross-bridges to form, making heart contract more forcefully.

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18
Q

The SNS _____ the Frank-Starling Mechanism.

A

Increases (by increasing Ca2+ influx)

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19
Q

With the Frank-Starling Mechanism, high MAP _____ contractility and therefore SV

A

decreases

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20
Q

Blood volume is sensed by…

A

venous, atrial and arterial baroreceptors

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21
Q

Normal blood volume is approximately ___ for men.

A

69 mL/kg

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22
Q

Normal blood volume is approximately ___ for women.

A

65 mL/kg

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23
Q

Blood volume is ultimatrly determined by…

A

fluid intake/output and thus renal function

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24
Q

Hear failure entails:

A

Problems with cardiac muscle, such as the inability to relax and expand during diastole or insufficient force to eject blood during systole

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25
Q

Low central venous pressure could be due to:

A

Abnormal vasodilation from postural hypotension, autonomic dysfunction or shock

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26
Q

Low blood volume is usually due to:

A

Dehydration or hemorrhage

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27
Q

High blood volume is often d/t:

A

Kidney’s reponse to low BP associated w/HF

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28
Q

Problems with afterload:

A

The stiffening of large arteries and increased resistance in smaller constricted arteries w/age

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29
Q

TRUE or FALSE: A change in BP is the only stimulus activating the cardiovascular integrating center in the medulla.

A

FALSE

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30
Q

Characteristics of brain blood flow:

A

Sufficient MAP is needed to overcome gravity. The cranium exerts ICP, a significant factor in CPP.

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31
Q

Brain blood flow becomes insufficient when intracranial pressure (ICP)…

A

rises

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32
Q

CPP =

A

CPP = MAP - ICP

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33
Q

After a concussion,

A

Blood flow does not return to normal for more than 1 mo (even after Sx have resolved).

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34
Q

“Second impact syndrome” causes much more damage because:

A

Inflammation causes ‘tightness’ and normal autoregulation of blood is impaired, so small increases in brain blood colume or edema causes a sharp increase in ICP

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35
Q

Why are children especially prone to TBI?

A

The brain reaches full size at age 6, but the cranium does not finish growing until age 16, leaving less room to expand when injury or edema occurs

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36
Q

Perisyncope

A

Feeling faint but recovering before falling

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37
Q

Hypovolemic hypotension

A

d/t loss of blood or other fluids (vomiting/diarrhea) or heat stress (which causes vasodilation and sweating)

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38
Q

Postural Hypotension

A

Fall in BP upon standing; occurs when baroceptor reflex does not occur properly; common in people taking meds for hypertension like beta blockers

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39
Q

Vasovagal syncope:

A

Typically d/t strong emotions, which trigger SNS DECREASE & PARASYMPATHETIC INCREASE, loweriNg MAP

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40
Q

Carcinogenic Syncope

A

MOST SERIOUS, often found with arrhythmias and problems with electrical conduction, bradycardia, et al.

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41
Q

In order to be awake:

A

The reticular activating sys in the brainstem must be activated & at least one hemisphere must be functional

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42
Q

Syncope is essentially due to:

A

A transient drop in BP disruption O2 delivery to brain (detected by reticular activating sys)

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43
Q

Syncope can also be due to:

A

Low blood sugar

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44
Q

Syncope is characterized by:

A

Lightheadedness, blurred/darkened vision. Pallor upon recovery

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45
Q

Syncope can only occur…

A

in a sitting or standing position

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46
Q

______ can occur in any position and may be mistaken for syncope

A

Seizures

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47
Q

The long-term response to DECREASED BP involves

A

INCREASING blood volume

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48
Q

Constriction of renal arteries means less blood flow to the kidneys and a ___ GFR

A

lower

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49
Q

Increasing filtration pressure of the glumerular capillary (PGC) will _____ GFR.

A

Increase

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50
Q

Contracting the Afferent arteriole…

A

decreases GFR by decreasing PGC

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51
Q

Contracting the Efferent arteriole…

A

increases GFR by increasing PGC

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52
Q

Most of what the nephron filters…

A

is reabsorbed.

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53
Q

How is renal blood flow (and thus GFR) regulated?

A

(1) SNS nerves (stimulated by a drop in BP, stress, etc.) constrict EA & AA and increase MAP (2) Tubuloglomerular Feedback

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54
Q

How does Tubuloglomerular Feedback control renal blood flow?

A

When macula densa detect DECREASED Na+ & Cl- delivery, EA is dilated, INCREASING PGC and thus GFR. Conversely, an increase in NaCl triggers AA constriction, DECREASING GFR.

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55
Q

How much Na+ is reabsorbed in the PCT?

A

65~75%

56
Q

The loop of Henle…

A

Reabsorbs 15~20% sodium in a countercurrent system concentrating tubule fluid.

57
Q

Nephrons with longer loops of Henle make _____ fluid.

A

MORE concentrated.

58
Q

Sodium reabsorption in the DCT and collecting ducts is regulated by…

A

aldosterone & ADH

59
Q

Important BP sensors are located:

A

Outside the kidneys (e.g. carotid), w/in kidneys: (1) internal baroreceptors in the JGA that secrete renin and (2) macula densa cells sense tubular [NaCl]

60
Q

Which 2 hormone systems control sodium excretion?

A

Renin/Angiotebsin/Aldosterone & ANP

61
Q

Where is renin produced?

A

JGA

62
Q

Angiotensin is produced by the _____

A

liver

63
Q

Renin catalyzes…

A

The conversion of angiotensinogen to angiotensin I

64
Q

______ converts angiotensin I to angiotensin II.

A

angiotensin-converting enzyme (ACE)

65
Q

Due to the abundance of other hormones, plasma levels of angiotensin II are controlled by ____

A

renin

66
Q

SNS activity _____ renin release.

A

stimulates

67
Q

Low intrarenal BP _____ renin release.

A

stimulates

68
Q

Low [NaCl] in macula densa r/t low GFR r/t low MAP] _____ renin release.

A

stimulates

69
Q

Angiotensin II _____ renin release.

A

inhibits (negative feedback)

70
Q

Angiotensin II causes vasoconstriction which _____ TPR and thus MAP

A

increases

71
Q

Angiotensin II causes vasoconstriction of the EA, which _____ GFR

A

stabilizes

72
Q

Angiotensin II _____ thirst.

A

stimulates

73
Q

Angiotensin II _____ aldosterone release.

A

stimulates

74
Q

Angiotensin II _____ ADH release.

A

stimulates

75
Q

Aldosterone is produced by the…

A

adrenal cortex

76
Q

Aldosterone _____ Na+ absorption

A

increases

77
Q

Increasing Na+ absorption is followed by H2O absorption IF:

A

ADH has made the tubes permeable to water

78
Q

High extracellular K+ _____ ADH levels

A

increases

79
Q

Aldosterone II ____ aldosterone release

A

increases

80
Q

Aldosterone controls:

A

The activity/# Na+/K+/ATPase pumps in DCT and collecting ducts

81
Q

Urine volume/osmolarity is mostly regulated by

A

Antidiuretic hormone (ADH)

82
Q

ADH is produced by the…

A

posterior pituitary

83
Q

ADH _____ water reabsorption in DCT & collecting ducts

A

increasea

84
Q

ADH _____ arteriolar smooth muscle

A

contracts; causes increased TPR and thus MAP

85
Q

The DCT & collecting ducts are normally _______ to water

A

impermeable

86
Q

When DCT and collecting ducts become perneavle to water, tubular fluid…

A

leaves tubule down its osmotic gradient

87
Q

ADH makes the interstitial osmolarity very _____ d/t loop of Henle

A

high

88
Q

ADH release is stimulated by _____ plasma osmolarity.

A

increased

89
Q

ADH release is stimulated by significantly _____ blood volume.

A

low

90
Q

ADH release is ______ by angiotensin II.

A

stimulated

91
Q

Drugs like nicotine _____ ADH release.

A

stimulate

92
Q

_____ plasma osmolarity inhibits ADH release.

A

Decreased

93
Q

ADH release is inhibited by _____ blood volume.

A

increased

94
Q

ADH release is ________ by ANP.

A

inhibited

95
Q

Drugs like EtOH _____ ADH release.

A

inhibit

96
Q

How does ADH control thirst centers through osmoreceptors?

A

INCREASED plasma osmolarity stimulates thirst.

97
Q

How does ADH control thirst centers through blood volume sensors & baroreceptors?

A

Lower blood volume or pressure stimulates thirst.

98
Q

How does ADH control thirst centers hormonally?

A

by stimulating release of angiotensin II, which also causes thirst.

99
Q

What would happen if hemorrhage occurs without compensatory mechanisms?

A

(1) Decreased venous return d/t Frank-Starling Mechanism and (2) lack of brain perfusion when upright.

100
Q

Autotransfusion _____ reflex response.

A

occurs without any

101
Q

Autotransfusion causes:

A

A decrease in BP and thus capillary hydrostatic pressure, causing fluid to move into capillaries from tissues

102
Q

When hemorrhage occurs, ________ causes reflexive constriction of arterioles.

A

SNS activation

103
Q

What metabolic effect does SNS activation have?

A

Mobilization of glucose stores, elevating plasma glucose and this INCREASING plasma osmolarity, promoting significant further fluid reabsorption from tissues.

104
Q

When hemorrhage occurs, the baroceptor reflex…

A

increases HR & SV and causes vasoconstriction

105
Q

Are the immediate nervous responses to hemorrhage enough to compensate for blood loss?

A

No

106
Q

How do the kidneys initially respond to decreased blood volume?

A

The decreased glomerular hydrostatic pressure automatically decreases GFR, lowering sodium & water excretion. (This is helped by decreased renal blood flow r/t SNS activity.

107
Q

The macula densa release renin when…

A

BP is low, low NaCl delivery, increased SNS activity

108
Q

How does renin release compensate for blood volume loss?

A

Increased aldosterone (increased H2O and Na+ reabsorption), ADH (increased H2O reabsorption) and thirst. As a result, plasma volume increases.

109
Q

In simple terms, HF is:

A

decreased BP d/t insufficient CO

110
Q

The kidneys respond to HF the same was as hemorrhage by increasing…

A

SNS activity, renin (and thus angiotensin II, aldosterone and ADH) release

111
Q

With HF, the Frank-Starling Mechanism increases…

A

blood volume and vicariously contractility

112
Q

The renal response to HF stresses the heart b/c:

A

it cannot keep up with higher blood volume, resulting in peripheral/pulmonary edema

113
Q

Atrial natriuretic peptide (ANP) & brain natriuretic peptide (BNP) release is stimulated by…

A

atrial stretch indicating increased blood volume

114
Q

ANP & BNP reduce cardiac workload by…

A

(1) venodilation, lowering EDV, preload and SV & (2) arterial/arteriolar dilation, reducing TPR and afterload

115
Q

ANP & BNP stimulate the kidneys to…

A

Increase Na+ and H2O excretion by (1) dilate glomerular AA & constrict EA, thus increasing GFR, which (2) increases Na+ filtration and excretion, (3) inhibits Na+ reabsorption in collecting ducts

116
Q

Which measures treat HF by reducing cardiac workload?

A

(1) reduced dietary Na+, (2) diuretics, (3) vasodilators (decreasing L ventricular afterload), (4) modulation of neurohormone response (e.g. ACE inhibitors, beta-blockers) and (5) synthetic ANP to increase Na+ excretion to reduce blood volume

117
Q

Which measures treat HF by improving heart performance?

A

Inotropic (i.e. force-increasing) drugs to increase SV (e.g. Digitalis increases Ca2+ availability to increase contractile force); may stress heart.

118
Q

A main indicator of plasma osmolarity is…

A

Na+ concentration

119
Q

Normal plasma osmolarity is approximately

A

290 mOsm/L

120
Q

Hypoosmolarity is sensed by osmoreceptors, resulting in…

A

DECREASED thirst and DECREASED ADH releasd

121
Q

True hypoosmolarity is characterized by:

A

low Na+ AND overall hypoosmolarity

122
Q

True hypoosmolarity could be caused by:

A

(1) problems with osmoreceptors or set point, (2) alteration if thirst mechanism, (3) problems with ADH or renal re:to ADH, (4) drinking too much water before/during exercise

123
Q

True hypoosmolarity should cause the DCT & collecting ducts to…

A

remain impermeable to water

124
Q

Decreased plasma osmolarity should result in ______ urine osmolarity.

A

decreased

125
Q

Urine osmolarity can be measured by…

A

specific gravity

126
Q

During pregnancy:

A

The osmolarity set point is lowered; ADH release and INCREASED thirst occur at lower plasma osmolarity. ADH increases collecting duct permeability, so water flows out along concentration gradient. As a result, more water is retained and plasma osmolarity decreases.

127
Q

In psychogenic polydipsia…

A

thirst mechanisms are disrupted; ADH and urine volume INCREASE, urine becomes dilute. These mechanisms usually compensate sufficiently unless renal fcn is compromised.

128
Q

True loss of plasma volume can occur in cases of:

A

excess sweating, vomiting, diarrhea or ADH release d/t blood loss

129
Q

Water intoxication is characterized by:

A

Water intake exceeding the kidneys’ limits causing dilutional hyponatremia, causong H2O to enter cells through osmosis

130
Q

Marathon runners are especially prone to…

A

Dilutional hyponatremia from drinking to much water before or during exercise.

131
Q

Plasma hypoosmolarity is…

A

Manifested by high [Na+] with neurologic Sx (muscle weakness, lethargy, twitching, seizures, coma).

132
Q

Plasma hyperosmolarity can be d/t:

A

(1) sodium salts like sodium bicarb administration (2) insufficient water consumption (3) vomiting, diarrhea, swearing (usually hypoosmolar compared to plasma), (4) extrarenal water loss (e.g. increased ventilation d/t fever), (5) excessive renal water loss (d/t inability to secrete/respond to ADH)

133
Q

How can MVC cause diabetes insipidus?

A

TBI damages ADH secretion, resulting in an inability to reabsorb water across distal tubules and colleting ducts. Urine cannot be concentrates, resulting in large volumes of hypotonic urine.

134
Q

Hyperosmolarity is contingent on…

A

whether pt can drink enough water to replace lost fluids

135
Q

Nephrogenic diabetes insipidus:

A

The inability to respond to ADH, causing loss of large volumes of hypotonic urine; results from drugs/conditions changing the renal architecture and preventing propee responses to the fluid loss.

136
Q

Osmolar gap:

A

Difference b/w projected and actual plasma osmolarity.

137
Q

An osmolar gap greater than 10 mOsm/L…

A

is often due to an unmeasured osmole in addition to the usual K+, phosphate, etc. (ex. antifreeze or methanol poisoning)