Patho chap 29
17. Which of the following individuals is most likely to be experiencing vasodilation? A) A 51-year-old man with a history of hypertension who is taking a medication that blocks the effect of the renin-angiotensin-aldosterone system B) A 9-year-old boy who has been given an injection of epinephrine to preclude an anaphylactic reaction to a bee sting C) A 30-year-old woman who takes antihistamines to treat her seasonal allergies D) A 32-year-old man who takes a selective serotonin reuptake inhibitor for the treatment of depression
A Feedback: Angiotensin is a potent vasoconstrictor, and medications that block this induce vasodilation. Epinephrine is also a vasoconstrictor. Histamine is a vasodilator, so antihistamine medications are likely to induce vasoconstriction. Serotonin is a vasoconstrictor, so medications that block its reuptake and increase free levels are apt to promote vasoconstriction.
3. Which of the following statements most accurately captures a principle of blood flow? A) With constant pressure, a small increase in vessel radius results in an exponential increase in blood flow. B) Blood flow is primarily determined by blood viscosity and temperature. C) Blood flows most quickly in the small diameter peripheral capillaries. D) Smaller cross-sectional vessel area is associated with lower flow velocity.
A Feedback: Doubling the radius of a vessel is associated with a fourth-power increase in flow, provided pressure remains constant. Blood flow is primarily a function of blood pressure, resistance, and viscosity. The small size of capillaries is associated with quite slow velocity, given their large total combined cross-sectional area. Smaller cross-sectional area is associated with greater velocity.
4. A 72-year-old female has been told by her physician that she has a new heart murmur that requires her to go visit a cardiologist. Upon examination, the cardiologist informs the patient that she has aortic stenosis. After the cardiologist has left the room, the patient asks, "What caused this [aortic stenosis] to happen now?" The clinic nurse responds, A) "Heart murmurs result from tumultuous flow through a diseased heart valve that is too narrow and stiff. This flow causes a vibration called a murmur." B) "Aortic stenosis is commonly seen in elderly patients. Basically, there is a blockage in the valve that is causing blood to pool, causing decreased velocity of flow." C) "This is caused by a tear in one of the papillary muscles attached to the valve. They can do a procedure where they thread a catheter into the heart and reattach the muscle ends." D) "Because of the high amount of energy it takes to push blood through the aortic valve to the body, your valve is just had to work too hard and it is weakening."
A Feedback: Heart murmur results from turbulent flow through a diseased heart valve that may be too narrow, too stiff, or too floppy. This turbulent flow causes a vibration called a murmur.
1. As part of presurgical teaching for patients who are about to undergo a coronary artery bypass graft, a nurse is performing an education session with a group of surgical candidates. Which of the following teaching points best conveys an aspect of the human circulatory system? A) "The blood pressure varies widely between arteries and veins and between pulmonary and systemic circulation." B) "Only around one quarter of your blood is in your heart at any given time." C) "Blood pressure and blood volume roughly mimic one another at any given location in the circulatory system." D) "Left-sided and right-sided pumping action on each beat of the heart must equal each other to ensure adequate blood distribution."
A Feedback: There is a large variation between the higher pressure in the systemic circulatory system and arteries and the lower pressure in the pulmonary system and veins. Approximately 8% of the blood supply is in the heart at any given time. Blood pressure and blood volume are inversely proportionate. The body is able to accommodate short-term differences in left-sided and right-sided output.
16. When explaining to a patient why he only had minimal muscle damage following 99% occlusion of the left anterior descending artery, the nurse will explain this is primarily due to A) the possibility that the person has elevated INR levels that prevent blood from backlogging in the vessel. B) development of collateral circulation that builds channels between some of the smaller arteries usually when the flow is decreased gradually. C) good genetic makeup that allows occluded arteries to keep vasodilating to meet metabolic needs. D) the release of substances formed by special glands that transport the blood cell-by-cell through smaller spaces.
B Feedback: Collateral circulation is a mechanism for the long-term regulation of local blood flow. Anastomotic channels exist between some of the smaller arteries. These channels permit perfusion of an area by more than one artery. When the artery becomes occluded, these anastomotic channels increase in size, allowing blood from a patent artery to perfuse the area supplied by the occluded vessel.
9. An 81-year-old female client of a long-term care facility has a history of congestive heart failure. The nurse practitioner caring for the client has positioned her sitting up at an angle in bed and is observing her jugular venous distention. Why is jugular venous distention a useful indicator for the assessment of the client's condition? A) Increased cardiac demand causes engorgement of systemic blood vessels, of which the jugular vein is one of the largest. B) Blood backs up into the jugular vein because there are no valves at the point of entry into the heart. C) Peripheral dilation is associated with decreased stroke volume and ejection fraction. D) Heart valves are not capable of preventing backflow in cases of atrial congestion.
B Feedback: Because there are no valves at the entry points to the atria, congestion can result in engorgement of the jugular veins, which are proximal to the heart. Increased cardiac demand is not associated with engorgement of vessels or peripheral dilation.
15. A patient arrived at the emergency department 2 days after the development of "chest pressure" and "tightness" was treated with antacids thinking it was indigestion. His enzymes show a massive myocardial infarction (MI). Following angioplasty, the patient asks why so much muscle was damaged if only one vessel was blocked, the left circumflex. The nurse responds, A) "With any blockage in the heart, muscle damage always occurs." B) "If a major artery like the circumflex is occluded, the smaller vessels supplied by that vessel cannot restore the blood flow." C) "Since the circumflex artery supplies oxygenated blood flow to the posterior surface of the left ventricle, any amount of blockage will result in vital muscle tissue being lost." D) "When it comes to arteries in the heart, all vessels are equal, and any blockage causes a massive amount of damage that will not be restored."
B Feedback: Hyperemia cannot occur when the arteries that supply the capillary beds are narrowed. For example, if a major coronary artery becomes occluded, the opening of channels supplied by that vessel cannot restore blood flow.
11. A patient is experiencing impaired circulation secondary to increased systemic arterial pressure. Which of the following statements is the most relevant phenomenon? A) Increased preload due to vascular resistance B) High afterload because of backpressure against the left ventricle C) Impaired contractility due to aortic resistance D) Systolic impairment because of arterial stenosis
B Feedback: Increased pressure in the aorta and other arteries constitutes a greater amount of afterload work. This situation is not indicative of increased preload or impaired contractility. Systolic impairment is not a recognized characterization of inadequate cardiac performance.
18. When trying to explain to a new dialysis patient the movement of substances through the capillary pores, the nurse will explain that in the kidneys, the glomerular capillaries have A) no capillary openings since this would lead to extensive hemorrhage. B) small openings that allow large amounts of smaller molecular substances to filter through the glomeruli. C) large pores so that substances can pass easily through the capillary wall. D) endothelial cells that are joined by tight junctions that form a barrier to medication filtration.
B Feedback: The glomerular capillaries in the kidneys have small openings called fenestrations that pass directly through the middle of the endothelial cells. These allow large amounts of small molecular and ionic substances to filter through the glomeruli without having to pass through the clefts between the endothelial cells.
8. A pathologist is examining histological (tissue) samples from a client with an autoimmune disease. Which of the following characteristics of muscle samples would signal the pathologist that the samples are cardiac rather than skeletal muscle? A) The cell samples lack intercalated disks. B) The muscle cells have small and a few mitochondria. C) The cells have a poorly defined sarcoplasmic reticulum. D) The muscles are striated and composed of sarcomeres.
C Feedback: Cardiac cells have a less clearly defined sarcoplasmic reticulum than do skeletal muscles. They also have intercalated disks and large, numerous mitochondria. Both types of muscles are striated and composed of sarcomeres.
6. During an automobile accident where the patient is bleeding heavily, which vascular component is the most distensible and can store large quantities of blood that can be returned to the circulation at this time of need? A) Liver and pancreas B) Kidneys C) Veins D) Aorta
C Feedback: Compliance refers to the total quantity of blood that can be stored in a given portion of the circulation for each mm Hg rise in pressure. The most distensible of all vessels are the veins, which can increase their volume with only slight changes in pressure. This allows the veins to function as a reservoir for storing large quantities of blood that can be returned to the circulation when it is needed. The liver, pancreas, and kidneys are not vascular components.
19. A 51-year-old patient with a history of alcohol abuse and liver disease has low serum levels of albumin and presents with ascites (excess fluid in his peritoneal space) and jaundice. A health care professional would recognize that which of the following processes is most likely underlying his health problems? A) Low albumin is contributing to excess hydrostatic pressure and inappropriate fluid distribution. B) Low albumin is inducing hypertension and increased filtration of fluid into interstitial spaces. C) Insufficient albumin is causing insufficient absorption of fluid into the capillaries. D) Low albumin contributing to an inability to counter gravitational effects.
C Feedback: Deficits of plasma proteins like albumin result in insufficient amounts of fluid being absorbed into the capillary circulation by osmotic pressure. It is not a result of hydrostatic pressure, hypertension, or the effects of gravity.
10. As part of their orientation to a cardiac care unit, a group of recent nursing graduates is receiving a refresher in cardiac physiology from the unit educator. Which of the following teaching points best captures a component of cardiac function? A) "Efficient heart function requires that the ventricles do not retain any blood at the end of the cardiac cycle." B) "Recall that the heart sounds that we listen to as part of our assessments are the sounds of the myocardium contracting." C) "The diastolic phase is characterized by relaxation of ventricles and their filling with blood." D) "Aortic pressure will exceed ventricular pressure during systole."
C Feedback: Diastole is associated with ventricular filling and relaxation. Cardiac output is not 1
2. In which of the following situations would blood most likely rapidly relocate from central circulation to the lower extremities? A) A client undergoes a stress test on a treadmill. B) A client does isotonic exercises in a wheelchair. C) A client is helped out of bed and stands up. D) A client reclines from a sitting to supine position.
C Feedback: During a change in body position, blood is rapidly relocated from the central circulation (when the patient is recumbent) to the lower extremities (when the patient stands up). This results in a temporary drop in blood pressure known as postural hypotension and reflects the redistribution of blood in the body.
14. Analysis has shown that a client's right atrial pressure is 30 mm Hg. What is the most likely conclusion that the client's care team will draw from this piece of data? A) The result is likely normal and gravity dependent given the lack of valves in thoracic and central veins. B) The pressure is insufficient to provide adequate stroke volume and cardiac output. C) The pressure is excessive given that the right atrium should be at atmospheric pressure. D) Pressure pulsations are likely to be undetectable given the low atrial pressure.
C Feedback: Normal right atrial pressure is around 0 mm Hg, or atmospheric pressure. Right atrial pressure does not have a direct influence on stroke volume or pulse pressure.
12. In the ICU, the nurse hears an emergency cardiac monitor go off. The nurse looks at the telemetry and notices the patient has gone into ventricular tachycardia. The nurse will likely assess for signs/symptoms of A) development of hypertension with BP 190/98. B) oxygen deprivation with O2 saturation decreasing to approximately 90%. C) decreasing cardiac output due to less ventricular filling time. D) increasing cardiac index by correlating the volume of blood pumped by the heart with an individual's body surface area.
C Feedback: One of the dangers of ventricular tachycardia is a reduction in cardiac output because the heart does not have time to fill adequately.
20. While intubated for surgery, a patient has inadvertently had his vagus nerve stimulated. What effect would the surgical team expect to observe? A) Decreased vascular perfusion due to parasympathetic stimulation B) Decreased heart rate, contractility, and afterload C) Decreased heart rate as a result of parasympathetic innervation of the heart D) Decreased heart rate as a result of impaired acetylcholine reuptake
C Feedback: Vagal stimulation results in lowered heart rate as a result of parasympathetic stimulation. Vascular perfusion, contractility, and afterload would not be under direct effect. Acetylcholine reuptake would not be influenced.
21. A patient in the emergency department is experiencing a massive stroke with extremely low blood flow to the brain exhibited by a BP less than 60 mm Hg. The nurse suddenly notes there is a sharp rise in the BP to 250 mm Hg. This high BP lasts about 5 minutes, and then the BP drops sharply again. The pathophysiologic principle behind this is likely due to the A) activation of the autonomic nervous system. B) release of mineralocorticoids. C) CNS ischemic response. D) protective homeostatic mechanism.
C Feedback: When blood flow to the brain has been sufficiently interrupted to cause ischemia of the vasomotor center, these vasomotor neurons become strongly excited. This causes massive vasoconstriction as a means of raising the blood pressure to levels as high as the heart can pump against. This response is called the CNS ischemic response and can raise BP to levels as high as 270 mm Hg for as long as 10 minutes.
7. A client has suffered damage to his pericardium following a motor vehicle accident. Which consequence could be a possible complication of damaged pericardium that his care providers should assess for? A) Impaired physical restraint of the left ventricle B) Increased friction during the contraction/relaxation cycle C) Reduced protection from infectious organisms D) Impaired regulation of myocardial contraction
D Feedback: Regulation of myocardial contraction is not a role of the fibrous covering around the heart. The pericardium does restrain the left ventricle, reduce friction by way of fluid in the pericardial cavity, and provide a physical barrier to infection.
5. A physician is teaching a group of medical students about the physiological basis for damage to the circulatory and neurological systems that can accompany hypotension. Which of the following responses by a student would warrant correction by the physician? A) "As vessel wall thickness increases, tension decreases." B) "Smaller blood vessels require more pressure to overcome wall tension." C) "The smaller the vessel radius, the greater the pressure needed to keep it open." D) "Tension and vessel thickness increase proportionately."
D Feedback: Tension and vessel wall thickness are inversely proportionate, in that thinner blood vessels have greater tension and vice versa. Answer choices A, B, and C all express the correct inverse relationship between tension and wall thickness.
13. A nurse is using a stethoscope and blood pressure cuff to manually measure a client's blood pressure. The nurse knows that which of the following facts related to blood flow underlies the ability to hear blood pressure by auscultation (listening)? A) The force of blood with each cardiac contraction produces friction on vessel walls that can be heard and felt. B) The movement of smooth muscle surrounding vessels produces noise that is audible by a stethoscope. C) Turbulent flow of blood during systole produces sound while laminar flow during diastole is silent. D) Pressure pulsation that exceeds the velocity of blood flow is audible and coincides with systolic BP.
D Feedback: The pressure pulsations that accompany intermittent blood ejection from the ventricles cause sounds that are audible when measuring blood pressure and palpable at pulse sites. Friction, muscle movement, and turbulent blood flow do not account for the pressure pulsations.