Physiology Unit 3 Quiz Questions

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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?

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?

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?

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?

100 ml/min Signup and view all the answers

What is the most likely cause of the patient's angina with decreased O2 content in coronary sinus blood?

Coronary blood flow decreased Signup and view all the answers

What is the most likely cause of swelling (edema) in patients with severe heart failure?

Increased Pc due to increased venous pressure Signup and view all the answers

What is the major mechanism by which a sudden increase in arterial blood pressure produces a rapid decrease in heart rate?

Increase in vagal efferent nerve activity Signup and view all the answers

What most likely happens at the onset of exercise?

Increased sympathetic outflow Signup and view all the answers

Which of the following best describes the velocity of blood in the vasculature with constant blood flow?

It is greater in the large veins than in the venules. Signup and view all the answers

When a pheochromocytoma discharges a large amount of epinephrine, what is the expected effect on heart rate?

Increase because epinephrine has a direct chronotropic effect on the heart. Signup and view all the answers

To calculate cardiac output (CO), which of the following must be known?

Heart rate and stroke volume Signup and view all the answers

Which of the following describes the action of the coronary arteries?

Dilated by adenosine Signup and view all the answers

In a patient with mitral stenosis, what would cardiac catheterization most likely indicate?

Increased pressure in the left atrium. Signup and view all the answers

Where is the pressure differential between the heart and aorta least?

Left ventricle during end diastole Signup and view all the answers

Which is true about the venous system?

Venous return increases during inspiration. Signup and view all the answers

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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Description

This quiz assesses your understanding of the physiological implications of low hemoglobin and the effects in a cardiac arrest scenario. Analyze the measurements provided and determine the correct conclusions regarding oxygen content and arterial pressures during cardiac arrest.