Oxygen Transport and Acid-Base Balance Quiz
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Questions and Answers

What is the primary chemical stimulus that regulates breathing?

  • Carbon dioxide levels (PCO2) (correct)
  • Nitrogen levels in the blood
  • pH levels in the blood
  • Oxygen levels (PO2)

What effect does increased cardiac output have during exercise?

  • It leads to an increase in heart size. (correct)
  • It causes a decrease in blood flow through capillaries.
  • It limits the amount of CO2 produced.
  • It decreases oxygen delivery to the muscles.

Which of the following describes the function of afferent input in the respiratory control center?

  • Controls the release of hormones affecting breathing.
  • Receives information about muscle activity and internal conditions. (correct)
  • Helps regulate ventilation during rest periods.
  • Sends information from the brain to muscles.

Which option accurately describes the role of central and peripheral chemoreceptors?

<p>They provide feedback on carbon dioxide and oxygen levels to the respiratory control center. (A)</p> Signup and view all the answers

What happens to ventilation in a trained individual compared to an untrained individual during exercise?

<p>Trained individuals exhibit more efficient oxygen binding due to higher hemoglobin affinity. (A)</p> Signup and view all the answers

What percentage of oxygen is transported in the blood bound to hemoglobin?

<p>99% (D)</p> Signup and view all the answers

What happens to oxygen release from hemoglobin during acute exercise?

<p>Oxygen release increases (D)</p> Signup and view all the answers

What is the primary form in which oxygen is transported in the blood?

<p>Bound to hemoglobin (D)</p> Signup and view all the answers

What is the effect of lower pH on the oxyhemoglobin dissociation curve?

<p>Shifts the curve to the right (D)</p> Signup and view all the answers

How many oxygen molecules can bind to one hemoglobin molecule?

<p>4 (B)</p> Signup and view all the answers

At rest, what percentage of oxygen bound to hemoglobin is typically dropped off to tissues?

<p>25% (D)</p> Signup and view all the answers

What is the primary reason for not releasing all the oxygen at rest?

<p>Low ATP requirement (B)</p> Signup and view all the answers

What characterizes the oxyhemoglobin curve at the highest partial pressure of oxygen?

<p>It is steep and flatter (C)</p> Signup and view all the answers

What is one of the main functions of the bicarbonate system in the blood?

<p>To convert CO2 into bicarbonate for transport (C)</p> Signup and view all the answers

What occurs to PCO2 during the transition from rest to work in exercise?

<p>It slightly decreases (B)</p> Signup and view all the answers

How does increased temperature affect ventilation during prolonged steady-state exercise?

<p>Ventilation begins to drift upward (C)</p> Signup and view all the answers

What is the ventilatory threshold (Tvent)?

<p>The point where VE increases exponentially (A)</p> Signup and view all the answers

What is the effect of chronic exercise training on ventilatory threshold?

<p>It increases the ventilatory threshold (B)</p> Signup and view all the answers

What happens to pH levels during incremental exercise?

<p>pH levels sharply drop (D)</p> Signup and view all the answers

What triggers increased ventilation rates when pH drops?

<p>Increased hydrogen ions in the blood (D)</p> Signup and view all the answers

Why does PO2 slightly decrease during the transition from rest to exercise?

<p>Because more oxygen is released to the working muscles (B)</p> Signup and view all the answers

What effect does an increase in temperature have on the oxyhemoglobin dissociation curve?

<p>It results in a rightward shift. (B)</p> Signup and view all the answers

Which of the following factors does NOT contribute to a rightward shift in the oxyhemoglobin dissociation curve?

<p>Increase of pH (A)</p> Signup and view all the answers

When does myoglobin primarily release oxygen?

<p>At very low PO2 (D)</p> Signup and view all the answers

What percentage of CO2 dissolves in the plasma from the skeletal muscle?

<p>10% (B)</p> Signup and view all the answers

What is the function of carbonic anhydrase in the context of CO2 transport?

<p>It catalyzes the reaction of CO2 and H2O to form carbonic acid. (D)</p> Signup and view all the answers

What happens to bicarbonate ions when they move out of red blood cells?

<p>They are replaced by chloride ions through the chloride shift. (B)</p> Signup and view all the answers

How is the majority of CO2 transported from the working skeletal muscle to the lung?

<p>By the bicarbonate system. (D)</p> Signup and view all the answers

What is the net effect of carbon dioxide and water reacting in the bicarbonate system?

<p>It produces bicarbonate and hydrogen ions. (C)</p> Signup and view all the answers

Flashcards

Oxygen transport to muscle

Oxygen is carried in the blood, primarily bound to hemoglobin (Hb).

Hb saturation

Approximately 99% of oxygen is transported bound to hemoglobin in the blood.

Oxyhemoglobin

Oxygen bound to hemoglobin.

Oxyhemoglobin Curve

Graph that shows how hemoglobin binds to and releases oxygen at varying partial pressures.

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Exercise and Hb release

During exercise, muscles need more oxygen. Lower oxygen partial pressure and lower pH in the blood, cause a shift in the oxyhemoglobin curve releasing more oxygen to the muscles.

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Bohr Effect

A rightward shift of the oxyhemoglobin dissociation curve, caused by lower pH, increased temperature, or increased carbon dioxide which promotes oxygen unload to tissues.

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Exercise and pH

Exercise causes the blood to become more acidic (lower pH).

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Oxygen release at rest

At rest, about 25% of the bound oxygen is released from Hb.

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Oxyhemoglobin Dissociation Curve Shift

The change in the oxyhemoglobin dissociation curve, which shows how oxygen binds to hemoglobin in relation to partial pressure of oxygen (PO2).

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Rightward Shift Cause

A decrease in PO2, pH, or an increase in temperature, all causing the release of oxygen from hemoglobin.

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Myoglobin's Role

Myoglobin is an oxygen-binding protein in skeletal muscle, acting as an oxygen storage site.

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Myoglobin Oxygen Release

Myoglobin releases oxygen when the partial pressure of oxygen (PO2) is very low.

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CO2 Transport

CO2 from working muscle is transported to the lungs primarily by the bicarbonate system, not bound to hemoglobin (Hb).

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Bicarbonate System

The bicarbonate system is a chemical buffering system that transports CO2 in the blood by converting it into bicarbonate.

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Chloride Shift

Bicarbonate moves out of the red blood cell, and chloride moves in to maintain electrochemical balance.

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High PCO2 Transport

High PCO2 Drives the bicarbonate reaction to the right in red blood cells, leading to bicarbonate production.

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PO2 decrease during exercise

During exercise, the partial pressure of oxygen (PO2) in the blood decreases despite increased oxygen demand.

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Ventilation during exercise

Ventilation increases during exercise to match the body's need for oxygen. This is controlled by both neural and humoral inputs to the respiratory control center.

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Humoral inputs to breathing

Humoral inputs that regulate breathing include central chemoreceptors (sensitive to CO2 in the CSF) and peripheral chemoreceptors (sensitive to O2 and CO2 in the blood).

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Efferent input and ventilation

Efferent neural input from the motor cortex contributes to increased ventilation during exercise, signaling the need for more oxygen to working muscles.

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Afferent inputs and muscle activity

Muscle spindles, Golgi tendon organs, and joint pressure receptors send afferent signals about muscle activity to the brain, influencing breathing.

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Bicarbonate system role

The bicarbonate system is used to transport approximately 70% of carbon dioxide in the blood, as only 10% can dissolve in the plasma directly.

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Ventilation during rest to work

At the start of exercise, ventilation increases quickly, followed by a slight decrease in PO2 and a slight decrease in PCO2. These plateaus after 1-2 minutes, ensuring optimal oxygen delivery to working muscles.

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Why does PO2 decrease slightly during work transition?

Initially, the body may not be delivering enough oxygen to meet the increased demands of working muscles, causing a slight decrease in PO2.

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Why does PCO2 decrease slightly during work transition?

The body may not be removing carbon dioxide fast enough initially, leading to a slight decrease in PCO2.

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Temperature impact on ventilation

During prolonged exercise, ventilation tends to drift upwards at warmer temperatures, even with little change in PCO2.

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Ventilation increase and workload

Ventilation does not increase linearly with increasing exercise intensity. It follows a linear increase up to 50-70% of VO2max, then levels off.

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pH changes during incremental exercise

With incremental exercise, blood pH decreases due to the presence of more hydrogen ions (H+). The body then increases ventilation to buffer these H+ ions.

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Ventilatory threshold (Tvent)

The ventilatory threshold (Tvent) is the inflection point at which ventilation increases exponentially. This point corresponds to the onset of blood lactate accumulation (OBLA).

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Study Notes

Oxygen Transport and Regulation

  • Oxygen is transported through the blood, primarily bound to hemoglobin (Hb) at approximately 99%.
  • Oxyhemoglobin is oxygen bound to Hb; deoxyhemoglobin is when oxygen is not bound.
  • Hemoglobin carries four oxygen molecules.
  • The percentage of oxygen saturation of Hb at rest after perfusion of skeletal muscle is 75%.
  • The oxyhemoglobin curve describes the binding of oxygen to Hb.
  • The partial pressure of oxygen in the alveoli capillaries (100 mmHg) is critical for oxygen binding to Hb.
  • At rest, 100 mmHg is the highest partial pressure of oxygen in the body.
  • The partial pressure of oxygen at rest is 40 mmHg.
  • Only 25% of oxygen bound to Hb is released at rest. This is to match the need for oxygen with the production.
  • Exercise increases the rate at which oxygen is released to meet higher demand.
  • Exercise causes a steeper and more rapid release of oxygen from hemoglobin..

Acid-Base Balance

  • Blood becomes more acidic during exercise.
  • More acidic blood leads to a rightward shift in the oxyhemoglobin dissociation curve, promoting the release of more oxygen to the tissues.
  • A decline in pH during exercise increases the amount of oxygen released to the working muscles.

Temperature

  • An elevated temperature during exercise causes a rightward shift in the oxyhemoglobin dissociation curve, promoting the release of more oxygen to the tissues.
  • This shift in the oxyhemoglobin curve facilitates the release of oxygen for muscular activity

Myoglobin

  • Myoglobin is an oxygen-binding protein found in skeletal muscle.
  • It acts as a storage site for oxygen.
  • Myoglobin releases oxygen quickly when oxygen levels are low, such as during exercise.

Carbon Dioxide Transport

  • 10% of CO2 is dissolved in plasma.
  • 20% is bound to hemoglobin.
  • 70% is transported in the blood as bicarbonate.
  • Bicarbonate is produced in red blood cells (RBCs).
  • Carbon dioxide converted to bicarbonate to move out of RBC to plasma to be exhaled in the lung.
  • The bicarbonate buffer system helps regulate pH.
  • High blood CO2 shifts the bicarbonate buffer system to release more CO2.

Ventilatory Control

  • PCO2 is the primary driver of ventilation.
  • Increased PCO2 stimulates an increase in ventilation rate.
  • Ventilation increases to match the increased need for oxygen associated with exercise.
  • Exercise intensity causes an exponential increase in ventilation rate.
  • Ventilatory threshold (VT) is the point where ventilation increases rapidly.
  • Ventilatory threshold occurs at or slightly before lactic acid build up.
  • Additional chemical signals such as hydrogen ions also play roles in regulating ventilation.

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Lecture 16: Oxygen Transport & CO2 Transport PDF

Description

Test your knowledge on the transport of oxygen in the blood and the regulation of acid-base balance during exercise. This quiz covers key concepts like hemoglobin function, oxygen saturation, and the effects of physical activity on oxygen release. Challenge yourself to understand how these processes interact in the human body.

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