1
Q
Atrial natriuretic peptide ____ (constricts/dilates) efferent renal arterioles and ____ (constricts/dilates) afferent arterioles.
A
Constricts; dilates (as a result, glomerular filtration rate is increased; ANP is cGMP mediated)
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2
Q
A 75-year-old man with exacerbated congestive heart failure has pitting edema. How is atrial natriuretic peptide affected?
A
Atrial natriuretic peptide increases due to increased blood volume and increased atrial pressure, and counteracts the effects of aldosterone
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3
Q
What is the “aldosterone escape” mechanism mediated by atrial natriuretic peptide?
A
cGMP-mediated afferent arteriole dilation and efferent arteriole constriction promotes diuresis and counteracts aldosterone
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4
Q
What is the effect of atrial natriuretic peptide on the renal collecting tubule?
A
ANP, released from atrial myocytes, promotes vasodilation and decreases the reabsorption of Na+ at the renal collecting tubule
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5
Q
BNP is released from ____ (atrial/ventricular) myocytes.
A
Ventricular (BNP functions similarly to ANP but with a longer half-life) (released in response to increased tension)
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6
Q
A 45-year-old man comes in with concern for heart failure. BNP is normal. Why is this important?
A
BNP has a good negative predictive value, so the patient likely does not have heart failure
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7
Q
A patient presents with shortness of breath. Heart failure is diagnosed and nesiritide is administered. What does this drug do?
A
Nesiritide is a recombinant form of B-type (brain) natriuretic peptide (BNP) acting similarly to ANP and useful for treating heart failure
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8
Q
Describe how blood pressure is related to the transmission of impulses from the aortic arch receptors to the medulla.
A
Aortic arch baroreceptor afferents travel via the vagus nerve to the solitary nucleus of the medulla in response to ↑ or ↓ blood pressure
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9
Q
Describe how blood pressure relates to the transmission of signals from carotid sinus receptors to the solitary nucleus of the medulla.
A
Baroreceptor afferents near dilated regions at the carotid bifurcations travel via the glossopharyngeal nerves to the medulla (↑ or ↓ BP)
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10
Q
Changes in which two parameters of brain interstitial fluid affect the response of central chemoreceptors?
A
pH and PCO2, which are influenced by arterial CO2 (central chemoreceptors do not directly respond to PO2)
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11
Q
A 30-year-old man falls and hits his head. Vitals = pulse of 43, BP of 150/100, RR of 8. Identify the reaction that explains these findings.
A
Cushing reaction (↑ intracranial pressure constricts arterioles, causing cerebral ischemia, reflex hypertension, and reflex bradycardia)
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12
Q
Are peripheral or central chemoreceptors responsible for the Cushing reaction?
A
Central chemoreceptors
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13
Q
A man is shot in the abdomen and bleeds heavily. Which type of receptor is most important in causing the body’s response to the hemorrhage?
A
Baroreceptors (these are most implicated in the body’s response to hypotension)
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14
A 50-year-old man presents to the ED after fainting while backing out of his driveway. What is the mechanism of his faint?
A
Turning his head (carotid sinus massage) → ↑ baroreceptor firing → ↑ AV node refractory period → ↓ HR and CO
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15
Q
Describe the body’s response after baroreceptors sense hypotension.
A
Decreased arterial pressure/stretch, less baroreceptor firing,↑sympathetic tone,↓parasympathetic tone, resulting in↑HR/BP/contractility
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16
Q
What chemical changes of the blood elicit a response from peripheral chemoreceptors? How do central chemoreceptors differ?
A
Low PO2 (
17
Q
What are the physical and chemical changes that contribute to the Cushing reaction (hypertension, bradycardia, and respiratory depression)?
A
↑ICP constricts arterioles →cerebral ischemia → ↑pCO2/↓pH → ↑CPP (hypertension) → ↑stretch → peripheral baroreceptor induced-bradycardia
18
Q
A woman is brought to the ICU for hypotension. What instrument can estimate her left atrial pressure? What are you actually measuring?
A
A Swan-Ganz catheter (pulmonary artery catheter); pulmonary capillary wedge pressure
19
Q
What is the normal pressure for the right atrium? The left atrium?
A
20
Q
What is the normal pressure for the right ventricle during systole and diastole? The left ventricle?
A
25/5 mmHg; 130/10 mmHg
21
Q
What is the normal pressure for the pulmonary artery during systole and diastole? The aorta?
A
25/10 mmHg; 130/90 mmHg
22
Q
A man has mitral stenosis. What would you expect his pulmonary capillary wedge pressure to be compared to his LV diastolic pressure?
A
• PCWP > left ventricular diastolic pressure
23
Q
The pulmonary vasculature is unique in that ____ causes vasoconstriction, whereas in other organs, it causes vasodilation.
A
Hypoxia (this ensures that only well-ventilated areas are perfused in the lung
24
Q
Which local metabolites govern autoregulation of perfusion of the heart? The brain? What specific change do they cause in the vasculature?
A
Carbon dioxide, adenosine, nitric oxide (NO), or decreased O2; carbon dioxide (pH); vasodilation
25
Q
What factors govern autoregulation of perfusion of the kidneys?
A
Myogenic and tubuloglomerular feedback
26
Q
What respective factors govern autoregulation of perfusion of the skeletal muscles during exercise? At rest?
A
During exercise = local metabolites such as lactate, adenosine, potassium, protons, carbon dioxide; at rest = sympathetic tone
27
Q
What factor governs autoregulation of perfusion of the skin? What is the effect on homeostasis?
A
Sympathetic stimulation; temperature control
28
Q
What is meant by autoregulation of blood flow?
A
The method by which blood flow to an organ remains constant over a wide range of perfusion pressures
29
Q
Baseline arterial O2 saturation is 87% in an 85-year-old man with COPD. How does this affect pulmonary vessels? How does it benefit him?
A
Hypoxia causes vasoconstriction, which allows for only well-ventilated areas to remain perfused; optimizes gas exchange
30
Q
How is net fluid flow (Jv) related to different pressures. Capillary permeability to fluid (Kf)? Capillary permeability to protein (ς)?
A
Jv = Kf × ([capillary pressure - interstitial fluid pressure] - ς × [plasma colloid pressure - interstitial fluid colloid pressure])
31
Q
• A 70-year-old woman has lower extremity pitting edema. Name four common changes in the net fluid flow equation that can cause edema.
A
↑capillary pressure, ↑capillary permeability, ↑interstitial colloid osmotic pressure, or ↓plasma protein content
32
Q
Which pressures, when increased, have a tendency to cause fluid to move from capillaries into tissues? From the tissue into capillaries?
A
Capillary fluid pressure and interstitial fluid colloid osmotic pressure; interstitial fluid pressure and plasma colloid osmotic pressure
33
Q
An 80-year-old man with a history of right-sided heart failure has ankle edema. In terms of capillary pressure, how did he develop edema?
A
Heart failure increases capillary pressure, which drives the fluid to move out of the capillaries and into the interstitium
34
Q
A 55-year-old man with alcoholic cirrhosis presents with pedal edema and ascites. In terms of capillary pressure, how did he develop edema?
A
Liver failure decreases plasma protein content, decreasing plasma oncotic pressure and causing fluid to move into the interstitium
35
Q
A 5-year-old boy presents with proteinuria and periorbital edema. In terms of capillary pressure, how did he develop edema?
A
He probably has minimal change disease (nephrotic syndrome), causing loss of plasma proteins and decreased colloid pressure, promoting edema
36
Q
What is the mechanism by which toxins, infections, and burns can cause edema?
A
Increased capillary permeability causes an increase in the filtration constant (Kf) leading to leakage into the interstitium
37
Q
A 50-year-old man from Africa presents with bilateral leg and scrotal edema due to elephantiasis. How did he develop edema?
A
Lymphatic obstruction caused increased interstitial colloid osmotic pressure, which caused fluid to move into the interstitium
