Cardiovascular 1 Flashcards
Blood pressure and volume. (137 cards)
1
Q
Total Peripheral Resistance is determined by the…
A
degree of vasoconstriction, primarily in the arterioles.
2
Q
Mean Arterial Pressure is primarily due to:
A
Blood Volume
3
Q
If BP is too high, renal mechanisms will generally…
A
INCREASE fluid loss in urine
4
Q
If BP is too low, mechanisms will…
A
RETAIN Na+ and H2O & INCREASE thirst
5
Q
Normal MAP is approximately:
A
100 mmHg
6
Q
Normal HR is approximately:
A
72 bpm
7
Q
Normal SV is approximately:
A
70 mL
8
Q
Normal CO is approximately:
A
5 L/min
9
Q
SNS activity ____ HR
A
INCREASES
10
Q
Parasympathetic activity ___ HR
A
DECREASES
11
Q
At rest, ______ nerve input predominates.
A
Parasympathetic
12
Q
In the heart, ____ is the preload (amt a muscle must stretch before contraction)
A
EDV
13
Q
In the heart, ____ is the afterload (force a muscle contracts against)
A
Arterial BP
14
Q
Frank-Starling Mechanism
A
Increasing EDV increases SV
15
Q
In hemorrhagic shock, the Frank-Starling Mechanism ensures:
A
Reduced blood volume leads to reduces CO
16
Q
In heart failure, the Frank-Starling Mechanism ensures:
A
Increased blood volume leads to increased CO (initially)
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.
18
Q
The SNS _____ the Frank-Starling Mechanism.
A
Increases (by increasing Ca2+ influx)
19
Q
With the Frank-Starling Mechanism, high MAP _____ contractility and therefore SV
A
decreases
20
Q
Blood volume is sensed by…
A
venous, atrial and arterial baroreceptors
21
Q
Normal blood volume is approximately ___ for men.
A
69 mL/kg
22
Q
Normal blood volume is approximately ___ for women.
A
65 mL/kg
23
Q
Blood volume is ultimatrly determined by…
A
fluid intake/output and thus renal function
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
25
Low central venous pressure could be due to:
Abnormal vasodilation from postural hypotension, autonomic dysfunction or shock
26
Low blood volume is usually due to:
Dehydration or hemorrhage
27
High blood volume is often d/t:
Kidney's reponse to low BP associated w/HF
28
Problems with afterload:
The stiffening of large arteries and increased resistance in smaller constricted arteries w/age
29
TRUE or FALSE: A change in BP is the only stimulus activating the cardiovascular integrating center in the medulla.
FALSE
30
Characteristics of brain blood flow:
Sufficient MAP is needed to overcome gravity. The cranium exerts ICP, a significant factor in CPP.
31
Brain blood flow becomes insufficient when intracranial pressure (ICP)...
rises
32
CPP =
CPP = MAP - ICP
33
After a concussion,
Blood flow does not return to normal for more than 1 mo (even after Sx have resolved).
34
"Second impact syndrome" causes much more damage because:
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
35
Why are children especially prone to TBI?
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
36
Perisyncope
Feeling faint but recovering before falling
37
Hypovolemic hypotension
d/t loss of blood or other fluids (vomiting/diarrhea) or heat stress (which causes vasodilation and sweating)
38
Postural Hypotension
Fall in BP upon standing; occurs when baroceptor reflex does not occur properly; common in people taking meds for hypertension like beta blockers
39
Vasovagal syncope:
Typically d/t strong emotions, which trigger SNS DECREASE & PARASYMPATHETIC INCREASE, loweriNg MAP
40
Carcinogenic Syncope
MOST SERIOUS, often found with arrhythmias and problems with electrical conduction, bradycardia, et al.
41
In order to be awake:
The reticular activating sys in the brainstem must be activated & at least one hemisphere must be functional
42
Syncope is essentially due to:
A transient drop in BP disruption O2 delivery to brain (detected by reticular activating sys)
43
Syncope can also be due to:
Low blood sugar
44
Syncope is characterized by:
Lightheadedness, blurred/darkened vision. Pallor upon recovery
45
Syncope can only occur...
in a sitting or standing position
46
______ can occur in any position and may be mistaken for syncope
Seizures
47
The long-term response to DECREASED BP involves
INCREASING blood volume
48
Constriction of renal arteries means less blood flow to the kidneys and a ___ GFR
lower
49
Increasing filtration pressure of the glumerular capillary (PGC) will _____ GFR.
Increase
50
Contracting the Afferent arteriole...
decreases GFR by decreasing PGC
51
Contracting the Efferent arteriole...
increases GFR by increasing PGC
52
Most of what the nephron filters...
is reabsorbed.
53
How is renal blood flow (and thus GFR) regulated?
(1) SNS nerves (stimulated by a drop in BP, stress, etc.) constrict EA & AA and increase MAP (2) Tubuloglomerular Feedback
54
How does Tubuloglomerular Feedback control renal blood flow?
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.
55
How much Na+ is reabsorbed in the PCT?
65~75%
56
The loop of Henle...
Reabsorbs 15~20% sodium in a countercurrent system concentrating tubule fluid.
57
Nephrons with longer loops of Henle make _____ fluid.
MORE concentrated.
58
Sodium reabsorption in the DCT and collecting ducts is regulated by...
aldosterone & ADH
59
Important BP sensors are located:
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
Which 2 hormone systems control sodium excretion?
Renin/Angiotebsin/Aldosterone & ANP
61
Where is renin produced?
JGA
62
Angiotensin is produced by the _____
liver
63
Renin catalyzes...
The conversion of angiotensinogen to angiotensin I
64
______ converts angiotensin I to angiotensin II.
angiotensin-converting enzyme (ACE)
65
Due to the abundance of other hormones, plasma levels of angiotensin II are controlled by ____
renin
66
SNS activity _____ renin release.
stimulates
67
Low intrarenal BP _____ renin release.
stimulates
68
Low [NaCl] in macula densa r/t low GFR r/t low MAP] _____ renin release.
stimulates
69
Angiotensin II _____ renin release.
inhibits (negative feedback)
70
Angiotensin II causes vasoconstriction which _____ TPR and thus MAP
increases
71
Angiotensin II causes vasoconstriction of the EA, which _____ GFR
stabilizes
72
Angiotensin II _____ thirst.
stimulates
73
Angiotensin II _____ aldosterone release.
stimulates
74
Angiotensin II _____ ADH release.
stimulates
75
Aldosterone is produced by the...
adrenal cortex
76
Aldosterone _____ Na+ absorption
increases
77
Increasing Na+ absorption is followed by H2O absorption IF:
ADH has made the tubes permeable to water
78
High extracellular K+ _____ ADH levels
increases
79
Aldosterone II ____ aldosterone release
increases
80
Aldosterone controls:
The activity/# Na+/K+/ATPase pumps in DCT and collecting ducts
81
Urine volume/osmolarity is mostly regulated by
Antidiuretic hormone (ADH)
82
ADH is produced by the...
posterior pituitary
83
ADH _____ water reabsorption in DCT & collecting ducts
increasea
84
ADH _____ arteriolar smooth muscle
contracts; causes increased TPR and thus MAP
85
The DCT & collecting ducts are normally _______ to water
impermeable
86
When DCT and collecting ducts become perneavle to water, tubular fluid...
leaves tubule down its osmotic gradient
87
ADH makes the interstitial osmolarity very _____ d/t loop of Henle
high
88
ADH release is stimulated by _____ plasma osmolarity.
increased
89
ADH release is stimulated by significantly _____ blood volume.
low
90
ADH release is ______ by angiotensin II.
stimulated
91
Drugs like nicotine _____ ADH release.
stimulate
92
_____ plasma osmolarity inhibits ADH release.
Decreased
93
ADH release is inhibited by _____ blood volume.
increased
94
ADH release is ________ by ANP.
inhibited
95
Drugs like EtOH _____ ADH release.
inhibit
96
How does ADH control thirst centers through osmoreceptors?
INCREASED plasma osmolarity stimulates thirst.
97
How does ADH control thirst centers through blood volume sensors & baroreceptors?
Lower blood volume or pressure stimulates thirst.
98
How does ADH control thirst centers hormonally?
by stimulating release of angiotensin II, which also causes thirst.
99
What would happen if hemorrhage occurs without compensatory mechanisms?
(1) Decreased venous return d/t Frank-Starling Mechanism and (2) lack of brain perfusion when upright.
100
Autotransfusion _____ reflex response.
occurs without any
101
Autotransfusion causes:
A decrease in BP and thus capillary hydrostatic pressure, causing fluid to move into capillaries from tissues
102
When hemorrhage occurs, ________ causes reflexive constriction of arterioles.
SNS activation
103
What metabolic effect does SNS activation have?
Mobilization of glucose stores, elevating plasma glucose and this INCREASING plasma osmolarity, promoting significant further fluid reabsorption from tissues.
104
When hemorrhage occurs, the baroceptor reflex...
increases HR & SV and causes vasoconstriction
105
Are the immediate nervous responses to hemorrhage enough to compensate for blood loss?
No
106
How do the kidneys initially respond to decreased blood volume?
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
The macula densa release renin when...
BP is low, low NaCl delivery, increased SNS activity
108
How does renin release compensate for blood volume loss?
Increased aldosterone (increased H2O and Na+ reabsorption), ADH (increased H2O reabsorption) and thirst. As a result, plasma volume increases.
109
In simple terms, HF is:
decreased BP d/t insufficient CO
110
The kidneys respond to HF the same was as hemorrhage by increasing...
SNS activity, renin (and thus angiotensin II, aldosterone and ADH) release
111
With HF, the Frank-Starling Mechanism increases...
blood volume and vicariously contractility
112
The renal response to HF stresses the heart b/c:
it cannot keep up with higher blood volume, resulting in peripheral/pulmonary edema
113
Atrial natriuretic peptide (ANP) & brain natriuretic peptide (BNP) release is stimulated by...
atrial stretch indicating increased blood volume
114
ANP & BNP reduce cardiac workload by...
(1) venodilation, lowering EDV, preload and SV & (2) arterial/arteriolar dilation, reducing TPR and afterload
115
ANP & BNP stimulate the kidneys to...
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
Which measures treat HF by reducing cardiac workload?
(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
Which measures treat HF by improving heart performance?
Inotropic (i.e. force-increasing) drugs to increase SV (e.g. Digitalis increases Ca2+ availability to increase contractile force); may stress heart.
118
A main indicator of plasma osmolarity is...
Na+ concentration
119
Normal plasma osmolarity is approximately
290 mOsm/L
120
Hypoosmolarity is sensed by osmoreceptors, resulting in...
DECREASED thirst and DECREASED ADH releasd
121
True hypoosmolarity is characterized by:
low Na+ AND overall hypoosmolarity
122
True hypoosmolarity could be caused by:
(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
True hypoosmolarity should cause the DCT & collecting ducts to...
remain impermeable to water
124
Decreased plasma osmolarity should result in ______ urine osmolarity.
decreased
125
Urine osmolarity can be measured by...
specific gravity
126
During pregnancy:
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
In psychogenic polydipsia...
thirst mechanisms are disrupted; ADH and urine volume INCREASE, urine becomes dilute. These mechanisms usually compensate sufficiently unless renal fcn is compromised.
128
True loss of plasma volume can occur in cases of:
excess sweating, vomiting, diarrhea or ADH release d/t blood loss
129
Water intoxication is characterized by:
Water intake exceeding the kidneys' limits causing dilutional hyponatremia, causong H2O to enter cells through osmosis
130
Marathon runners are especially prone to...
Dilutional hyponatremia from drinking to much water before or during exercise.
131
Plasma hypoosmolarity is...
Manifested by high [Na+] with neurologic Sx (muscle weakness, lethargy, twitching, seizures, coma).
132
Plasma hyperosmolarity can be d/t:
(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
How can MVC cause diabetes insipidus?
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
Hyperosmolarity is contingent on...
whether pt can drink enough water to replace lost fluids
135
Nephrogenic diabetes insipidus:
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
Osmolar gap:
Difference b/w projected and actual plasma osmolarity.
137
An osmolar gap greater than 10 mOsm/L...
is often due to an unmeasured osmole in addition to the usual K+, phosphate, etc. (ex. antifreeze or methanol poisoning)
