Cardiac Physiology Quiz

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Questions and Answers

What is the formula for calculating cardiac output?

Stroke volume multiplied by heart rate (correct)

Heart rate divided by stroke volume

Heart rate plus stroke volume

Stroke volume plus heart rate

What is the normal stroke volume in milliliters?

110 mL

90 mL

50 mL

70 mL (correct)

If the heart rate is 90 bpm, what is the cardiac output?

7200 mL/min

6300 mL/min (correct)

5400 mL/min

8100 mL/min

Which V/Q defect is indicated by a value of 0?

Dead space Signup and view all the answers

What is the closest value that indicates critical renal artery stenosis?

70% Signup and view all the answers

Which immunoglobulin provides localized protection in tears and intestinal secretions?

IgA Signup and view all the answers

In a clinical context, which of the following would be most helpful for addressing hypoxemia?

Supplementation of O2 for low V/Q defects Signup and view all the answers

What is the closest estimated cardiac output when taking into account a stroke volume of 70 mL and a heart rate of 90 bpm with a slight increase?

6.75 L/min Signup and view all the answers

What is the normal value for anatomic dead space in the lungs?

150 mL Signup and view all the answers

What condition is characterized by hyperresonance on percussion?

Pneumothorax Signup and view all the answers

What does increased alveolar dead space typically indicate?

V/Q mismatch Signup and view all the answers

Which hormone does pancreatic somatostatin inhibit?

Growth hormone and glucagon Signup and view all the answers

During which condition is dullness on percussion most commonly observed?

Atelectasis Signup and view all the answers

What is the primary physiological role of somatostatin?

Acts as an inhibitory hormone Signup and view all the answers

Which of the following correctly describes alveolar dead space?

Air that does not achieve gas exchange Signup and view all the answers

What is a potential clinical consequence of a V/Q mismatch?

Increased alveolar dead space Signup and view all the answers

What is the normal anatomic dead space in relation to tidal volume?

150 ml and approximately 30% of 500 ml tidal volume Signup and view all the answers

Which factor in the Bohr equation affects the calculation of dead space?

Tidal volume (VT) Signup and view all the answers

A deficiency in which enzyme is associated with male pseudohermaphroditism?

5-alpha reductase Signup and view all the answers

What causes the female pseudohermaphroditism related to 21-beta hydroxylase deficiency?

Excessive production of weak androgens Signup and view all the answers

Which calculation provides the alveolar ventilation rate?

Tidal volume (VT) minus dead space multiplied by breathing frequency Signup and view all the answers

What is a characteristic feature of the anatomic dead space?

It does not participate in effective ventilation. Signup and view all the answers

Which volume is typically used for calculating dead space in respiratory physiology?

Tidal volume Signup and view all the answers

For a patient with normal tidal volume, how would dead space be expressed when considering a PCO2 difference?

As a fraction of the tidal volume Signup and view all the answers

Study Notes

Cardiac Output and Stroke Volume

Cardiac output (CO) is calculated by multiplying stroke volume (SV) and heart rate (HR).
Normal stroke volume averages around 70 mL.
CO formula: CO = SV x HR; thus, 70 mL x 90 bpm results in a CO of 6300 mL/min or 6.3 L/min.
A common value for normal cardiac output among choices is 6.75 L/min.

Ventilation-Perfusion (V/Q) Defects

Different types of V/Q defects exist:
- V/Q = 0: Indicates complete shunting or no ventilation.
- Dead Space: Areas of the lungs where ventilation occurs, but no perfusion, leading to wasted effort in breathing.
- Low V/Q: Occurs when insufficient ventilation relative to perfusion happens.

Immunoglobulin Functions

Immunoglobulin A (IgA) provides localized protection in mucosal areas, such as tears and intestinal secretions.

Renal Artery Stenosis

Defined as a reduction of more than 70% in the diameter of the renal artery, based on recent consensus guidelines.

Respiratory Mechanics

The normal anatomical dead space measures about 150 mL, approximately 30% of a normal tidal volume of 500 mL.
Physiological dead space equals anatomical plus alveolar dead spaces.
A patient's tidal volume multiplied by the difference in arterial carbon dioxide pressure (PCO2) and expired PCO2 helps calculate dead space.

Hormonal Regulation

Somatostatin: Acts as an inhibitory hormone, inhibiting growth hormone, insulin, and glucagon.
21-beta Hydroxylase: Critical enzyme linked to female pseudohermaphroditism, where genotypically female individuals present with congenital anomalies due to excess androgens.

Breathing and Lung Compliance

Increased lung compliance lowers intrathoracic pressure, promoting chest wall expansion.
Lack of gas exchange primarily occurs in anatomical dead spaces, particularly in the conducting zone of the lungs, with a normal value of 150 mL.
Alveolar dead space typically has a normal value of 0 mL, as ideally, all alveoli should participate in gas exchange.

Conditions Affecting Lung Function

Atelectasis is characterized by dullness on percussion, while pneumothorax creates hyperresonance.
Status asthmaticus displays wheezing or silent chest conditions indicative of severe airway obstruction.

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Description

Test your understanding of cardiac output, stroke volume, and the role of oxygen supplementation in hypoxemia. This quiz will cover key concepts related to heart physiology and function. Challenge your knowledge and see how well you grasp these vital elements of cardiac health.