PT 508 A&P Review

Questions and Answers

What is the formula to calculate cardiac output?

CO = SV + HR

CO = HR / SV

CO = SV - HR

CO = SV × HR (correct)

Which term describes the resistance of ejected blood volume to flow?

Stroke volume

Afterload (correct)

Preload

Cardiac output

What does the oxygen extraction ratio represent?

Ratio of O2 consumption to O2 delivery (correct)

Total volume of oxygen in blood at rest

Amount of CO2 produced per liter of blood

Difference between O2 delivery and O2 consumption

Which of the following factors does NOT impact oxygen transport?

Body mass index Signup and view all the answers

What is the role of the diaphragm during respiration?

It contracts for inhalation Signup and view all the answers

In critically ill patients, what may limit oxygen delivery?

Limited delivery of O2 Signup and view all the answers

What is oxygen debt?

Difference between O2 consumption and O2 delivery Signup and view all the answers

Which muscle is NOT typically involved in inspiration?

Trapezius Signup and view all the answers

What is the primary determinant of the convection of oxygen from lung alveoli to tissue capillaries?

Cardiac output Signup and view all the answers

Which statement correctly describes the diffusion of oxygen?

O2 moves from capillaries to cells or across the alveolar-capillary membrane Signup and view all the answers

When at rest, how does the oxygen delivery (DO2) compare to the actual oxygen consumption (VO2)?

DO2 is approximately 3 to 4 times more than VO2 Signup and view all the answers

What is one impact of exercise on oxygen consumption (VO2) in healthy individuals?

VO2 can increase up to 20 times higher than at rest Signup and view all the answers

What is the average hematocrit percentage in women?

38% Signup and view all the answers

What percentage of blood is typically found in the systemic arteries?

10% Signup and view all the answers

Which factor does NOT affect DO2 in various illnesses?

Exercise intensity Signup and view all the answers

What component predominantly constitutes blood?

Red blood cells Signup and view all the answers

What is typically the nature of expiration in healthy individuals?

A passive process Signup and view all the answers

What does S1 heart sound correspond to?

Closure of the mitral and tricuspid valves Signup and view all the answers

Which pressure is responsible for fluid filtering into the interstitial space?

Capillary hydrostatic pressure Signup and view all the answers

At what PO2 level does oxygen dissociation from hemoglobin typically start to increase significantly?

Above 80 mmHg Signup and view all the answers

What event triggers the lower pH associated with acute respiratory acidosis?

Increased CO2 retention Signup and view all the answers

Which factors are critical for effective ventilation-perfusion matching?

Ratio of blood flow to air exchange Signup and view all the answers

Where is the highest ventilation observed in the lungs?

Lower lung fields Signup and view all the answers

What physiological mechanism helps to match ventilation in areas of low oxygen concentration?

Hypoxic vasoconstriction Signup and view all the answers

Which of the following best describes the process of diffusion in the respiratory system?

Gas exchange occurs across thickened membranes in disease states Signup and view all the answers

What is the typical V/Q ratio that maintains normal physiological function?

0.8 Signup and view all the answers

Which components are involved in central control of ventilation?

Medulla and pontine centers Signup and view all the answers

What characterizes the sound S3 in heart auscultation?

It suggests possible ventricular failure Signup and view all the answers

Study Notes

Oxygen Transport Overview

Continuous oxygen is essential for various biological functions including muscle contractions and cellular metabolism.
Oxygen delivery (DO2) at rest is 3 to 4 times more than the body's requirements; during exercise, VO2 can increase up to 20 times higher than resting levels.

Principles of Oxygen Transport

Convection and diffusion are the primary mechanisms; convection involves oxygen moving from lungs to tissue capillaries, influenced by hemoglobin levels and cardiac output (CO = Stroke Volume x Heart Rate).
Diffusion occurs at the cellular level, where O2 moves from capillaries to cells based on factors like metabolic rate and tissue thickness.

Factors Influencing Oxygen Delivery

Oxygen saturation levels at the alveolar level and blood volume (average 5000 mL) significantly impact O2 transport capabilities.
Quality of blood is determined by the composition of red blood cells, white blood cells, and platelets; healthy hematocrit averages are 38% in women and 42% in men.

Cardiac Output and Function

Cardiac output (CO) is calculated by multiplying stroke volume (SV) by heart rate (HR).
Preload refers to the ventricular stretch before contraction, while afterload is the resistance faced during blood ejection.

External Factors Affecting Oxygen Transport

Gravity, exercise, and stress can modify oxygen transport efficiency.
Oxygen extraction ratio (VO2/DO2) typically remains around 23% at rest; critical illness can compromise this ratio.

Respiratory Muscles

Primary muscles for inspiration: diaphragm, intercostals, sternocleidomastoid, and scalenes; these muscles contract primarily to draw air into the lungs.
Expiration is usually passive but may involve additional muscle engagement during exertion or respiratory distress, incorporating rectus abdominis and internal intercostals.

Heart Sounds and Cardiac Anatomy

Normal heart sounds include S1 (closure of mitral and tricuspid valves) and S2 (closure of aortic and pulmonary valves); additional sounds (S3 and S4) can indicate abnormalities such as ventricular failure or stiff ventricles.

Diffusion and Perfusion Dynamics

Oxygen crosses alveolar-capillary membranes effectively but can be hindered in disease states where membrane thickness increases.
Perfusion must occur with adequate blood flow to facilitate gas exchange; hypoxic vasoconstriction occurs in regions of low oxygen.

Ventilation-Perfusion Ratio

Optimal V/Q ratio for gas exchange is approximately 0.8, representing a balance of four parts ventilation to five parts perfusion.
V/Q mismatching can lead to inefficiencies in oxygen uptake and carbon dioxide removal.

Mechanisms of CO2 Transport

Produced from cellular metabolism, CO2 is transported back to the lungs. Chemical reactions in the blood help buffer CO2 and manage pH levels.
Poor ventilation can elevate CO2 levels leading to acute respiratory acidosis.

Central Control of Ventilation

The respiratory rate is regulated by central and peripheral chemoreceptors, alongside control centers in the medulla and pons.
Factors such as lung compliance and airway resistance influence ventilation efficiency and respiratory function.

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Description

This quiz covers essential concepts in Anatomy and Physiology, focusing on oxygen transport, thoracic anatomy, and normal cardiac function. Students will review ventilation and perfusion, enhancing their understanding of respiratory and circulatory systems. Prepare to test your knowledge and solidify your learning!