Atrial natriuretic peptide- B-type (brain) natriuretic peptide- Baroreceptors and chemoreceptors-Normal pressures- Autoregulation- Capillary fluid exchange

Question 1

Atrial natriuretic peptide ____ (constricts/dilates) efferent renal arterioles and ____ (constricts/dilates) afferent arterioles.

Answer 1

Constricts; dilates (as a result, glomerular filtration rate is increased; ANP is cGMP mediated)

Question 2

A 75-year-old man with exacerbated congestive heart failure has pitting edema. How is atrial natriuretic peptide affected?

Answer 2

Atrial natriuretic peptide increases due to increased blood volume and increased atrial pressure, and counteracts the effects of aldosterone

Question 3

What is the “aldosterone escape” mechanism mediated by atrial natriuretic peptide?

Answer 3

cGMP-mediated afferent arteriole dilation and efferent arteriole constriction promotes diuresis and counteracts aldosterone

Question 4

What is the effect of atrial natriuretic peptide on the renal collecting tubule?

Answer 4

ANP, released from atrial myocytes, promotes vasodilation and decreases the reabsorption of Na+ at the renal collecting tubule

Question 5

BNP is released from ____ (atrial/ventricular) myocytes.

Answer 5

Ventricular (BNP functions similarly to ANP but with a longer half-life) (released in response to increased tension)

Question 6

A 45-year-old man comes in with concern for heart failure. BNP is normal. Why is this important?

Answer 6

BNP has a good negative predictive value, so the patient likely does not have heart failure

Question 7

A patient presents with shortness of breath. Heart failure is diagnosed and nesiritide is administered. What does this drug do?

Answer 7

Nesiritide is a recombinant form of B-type (brain) natriuretic peptide (BNP) acting similarly to ANP and useful for treating heart failure

Question 8

Describe how blood pressure is related to the transmission of impulses from the aortic arch receptors to the medulla.

Answer 8

Aortic arch baroreceptor afferents travel via the vagus nerve to the solitary nucleus of the medulla in response to ↑ or ↓ blood pressure

Question 9

Describe how blood pressure relates to the transmission of signals from carotid sinus receptors to the solitary nucleus of the medulla.

Answer 9

Baroreceptor afferents near dilated regions at the carotid bifurcations travel via the glossopharyngeal nerves to the medulla (↑ or ↓ BP)

Question 10

Changes in which two parameters of brain interstitial fluid affect the response of central chemoreceptors?

Answer 10

pH and PCO2, which are influenced by arterial CO2 (central chemoreceptors do not directly respond to PO2)

Question 11

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.

Answer 11

Cushing reaction (↑ intracranial pressure constricts arterioles, causing cerebral ischemia, reflex hypertension, and reflex bradycardia)

Question 12

Are peripheral or central chemoreceptors responsible for the Cushing reaction?

Answer 12

Central chemoreceptors

Question 13

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?

Answer 13

Baroreceptors (these are most implicated in the body’s response to hypotension)

Question 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?

Answer 14

Turning his head (carotid sinus massage) → ↑ baroreceptor firing → ↑ AV node refractory period → ↓ HR and CO

Question 15

Describe the body’s response after baroreceptors sense hypotension.

Answer 15

Decreased arterial pressure/stretch, less baroreceptor firing,↑sympathetic tone,↓parasympathetic tone, resulting in↑HR/BP/contractility

Question 16

What chemical changes of the blood elicit a response from peripheral chemoreceptors? How do central chemoreceptors differ?

Answer 16

Low PO2 (

Question 17

What are the physical and chemical changes that contribute to the Cushing reaction (hypertension, bradycardia, and respiratory depression)?

Answer 17

↑ICP constricts arterioles →cerebral ischemia → ↑pCO2/↓pH → ↑CPP (hypertension) → ↑stretch → peripheral baroreceptor induced-bradycardia

Question 18

A woman is brought to the ICU for hypotension. What instrument can estimate her left atrial pressure? What are you actually measuring?

Answer 18

A Swan-Ganz catheter (pulmonary artery catheter); pulmonary capillary wedge pressure

Question 19

What is the normal pressure for the right atrium? The left atrium?

Question 20

What is the normal pressure for the right ventricle during systole and diastole? The left ventricle?

Answer 20

25/5 mmHg; 130/10 mmHg

Question 21

What is the normal pressure for the pulmonary artery during systole and diastole? The aorta?

Answer 21

25/10 mmHg; 130/90 mmHg

Question 22

A man has mitral stenosis. What would you expect his pulmonary capillary wedge pressure to be compared to his LV diastolic pressure?

Answer 22

• PCWP > left ventricular diastolic pressure

Question 23

The pulmonary vasculature is unique in that ____ causes vasoconstriction, whereas in other organs, it causes vasodilation.

Answer 23

Hypoxia (this ensures that only well-ventilated areas are perfused in the lung

Question 24

Which local metabolites govern autoregulation of perfusion of the heart? The brain? What specific change do they cause in the vasculature?

Answer 24

Carbon dioxide, adenosine, nitric oxide (NO), or decreased O2; carbon dioxide (pH); vasodilation

Question 25

What factors govern autoregulation of perfusion of the kidneys?

Answer 25

Myogenic and tubuloglomerular feedback

Question 26

What respective factors govern autoregulation of perfusion of the skeletal muscles during exercise? At rest?

Answer 26

During exercise = local metabolites such as lactate, adenosine, potassium, protons, carbon dioxide; at rest = sympathetic tone

Question 27

What factor governs autoregulation of perfusion of the skin? What is the effect on homeostasis?

Answer 27

Sympathetic stimulation; temperature control

Question 28

What is meant by autoregulation of blood flow?

Answer 28

The method by which blood flow to an organ remains constant over a wide range of perfusion pressures

Question 29

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?

Answer 29

Hypoxia causes vasoconstriction, which allows for only well-ventilated areas to remain perfused; optimizes gas exchange

Question 30

How is net fluid flow (Jv) related to different pressures. Capillary permeability to fluid (Kf)? Capillary permeability to protein (ς)?

Answer 30

Jv = Kf × ([capillary pressure - interstitial fluid pressure] - ς × [plasma colloid pressure - interstitial fluid colloid pressure])

Question 31

• A 70-year-old woman has lower extremity pitting edema. Name four common changes in the net fluid flow equation that can cause edema.

Answer 31

↑capillary pressure, ↑capillary permeability, ↑interstitial colloid osmotic pressure, or ↓plasma protein content

Question 32

Which pressures, when increased, have a tendency to cause fluid to move from capillaries into tissues? From the tissue into capillaries?

Answer 32

Capillary fluid pressure and interstitial fluid colloid osmotic pressure; interstitial fluid pressure and plasma colloid osmotic pressure

Question 33

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?

Answer 33

Heart failure increases capillary pressure, which drives the fluid to move out of the capillaries and into the interstitium

Question 34

A 55-year-old man with alcoholic cirrhosis presents with pedal edema and ascites. In terms of capillary pressure, how did he develop edema?

Answer 34

Liver failure decreases plasma protein content, decreasing plasma oncotic pressure and causing fluid to move into the interstitium

Question 35

A 5-year-old boy presents with proteinuria and periorbital edema. In terms of capillary pressure, how did he develop edema?

Answer 35

He probably has minimal change disease (nephrotic syndrome), causing loss of plasma proteins and decreased colloid pressure, promoting edema

Question 36

What is the mechanism by which toxins, infections, and burns can cause edema?

Answer 36

Increased capillary permeability causes an increase in the filtration constant (Kf) leading to leakage into the interstitium

Question 37

A 50-year-old man from Africa presents with bilateral leg and scrotal edema due to elephantiasis. How did he develop edema?

Answer 37

Lymphatic obstruction caused increased interstitial colloid osmotic pressure, which caused fluid to move into the interstitium