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Questions and Answers
What can be concluded from the O2 saturation of 95% and a hemoglobin of 9g/100ml of blood in the patient?
What can be concluded from the O2 saturation of 95% and a hemoglobin of 9g/100ml of blood in the patient?
- Nasal O2 would be beneficial (correct)
- Her O2 content is normal
- Her O2 content is low (correct)
- Her hematocrit is probably normal
What would be the expected pressure in the systemic arteries and veins during cardiac arrest?
What would be the expected pressure in the systemic arteries and veins during cardiac arrest?
- The pressure would equilibrate to a level closer to the normal venous pressure, around 7 mm Hg. (correct)
- The pressure would equilibrate to a level close to the normal arterial pressure.
- The pressure in the arteries and veins would be zero at equilibrium.
- The pressure in the arteries would be greater than in the veins.
Which of the following would produce the greatest increase in blood flow through an exercising skeletal muscle?
Which of the following would produce the greatest increase in blood flow through an exercising skeletal muscle?
- Decrease the length of the capillaries by 50%
- Double the pressure gradient across the vascular bed
- Decrease the blood viscosity by 50%
- Double the radius of the venules
- Double the radius of the arterioles (correct)
What is the O2 consumption of the isolated skeletal muscle measured at a blood flow of 20 ml/min?
What is the O2 consumption of the isolated skeletal muscle measured at a blood flow of 20 ml/min?
What is the most likely cause of the patient's angina with decreased O2 content in coronary sinus blood?
What is the most likely cause of the patient's angina with decreased O2 content in coronary sinus blood?
What is the most likely cause of swelling (edema) in patients with severe heart failure?
What is the most likely cause of swelling (edema) in patients with severe heart failure?
What is the major mechanism by which a sudden increase in arterial blood pressure produces a rapid decrease in heart rate?
What is the major mechanism by which a sudden increase in arterial blood pressure produces a rapid decrease in heart rate?
What most likely happens at the onset of exercise?
What most likely happens at the onset of exercise?
Which of the following best describes the velocity of blood in the vasculature with constant blood flow?
Which of the following best describes the velocity of blood in the vasculature with constant blood flow?
When a pheochromocytoma discharges a large amount of epinephrine, what is the expected effect on heart rate?
When a pheochromocytoma discharges a large amount of epinephrine, what is the expected effect on heart rate?
To calculate cardiac output (CO), which of the following must be known?
To calculate cardiac output (CO), which of the following must be known?
Which of the following describes the action of the coronary arteries?
Which of the following describes the action of the coronary arteries?
In a patient with mitral stenosis, what would cardiac catheterization most likely indicate?
In a patient with mitral stenosis, what would cardiac catheterization most likely indicate?
Where is the pressure differential between the heart and aorta least?
Where is the pressure differential between the heart and aorta least?
Which is true about the venous system?
Which is true about the venous system?
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Study Notes
Patient Measurements and Angina
- A 55-year-old female with 95% O2 saturation and hemoglobin of 9g/100ml indicates potential low O2 content.
- In cardiac arrest, systemic arterial and venous pressure will equilibrate closer to normal venous pressure (~7 mm Hg).
- A sudden increase in arterial blood pressure typically causes a rapid decrease in heart rate due to increased vagal efferent activity.
Blood Flow and Exercise
- Greatest increase in blood flow in exercising skeletal muscle occurs by doubling the radius of arterioles.
- During exercise, sympathetic outflow increases while coronary blood flow may decrease.
O2 Consumption in Skeletal Muscle
- O2 consumption calculated using blood flow and arterial/venous O2 content difference: 20 ml/min x (15 ml/ml - 10 ml/ml) = 100 ml/min.
Mechanisms of Edema
- In severe heart failure, edema results primarily from increased venous pressure (Pc) leading to fluid extravasation.
Physiological Responses
- Coronary arteries dilate via adenosine and constrict in response to norepinephrine.
- At the onset of exercise, cerebral blood flow may decrease.
- Heart rate increases in response to a pheochromocytoma due to direct effects of epinephrine.
Cardiac Output Calculations
- Cardiac output (CO) is determined by heart rate and stroke volume.
- Mitral stenosis leads to increased pressure in the left atrium during cardiac catheterization.
Venous Pressure Dynamics
- Upright position results in approximately 7 mm Hg venous pressure at the ankle, while supine position sees ~100 mm Hg at heart level.
- Venous return increases during inspiration as thoracic cavity pressure changes enhance blood flow to the heart.
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