Oxygen Transport and Diffusion Quiz

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Questions and Answers

How does the partial pressure of oxygen (PO2) affect hemoglobin's affinity for oxygen?

High PO2 decreases hemoglobin's affinity for oxygen

PO2 has no effect on hemoglobin's affinity for oxygen

High PO2 increases hemoglobin's affinity for oxygen (correct)

Low PO2 increases hemoglobin's affinity for oxygen

What primarily increases the diffusing capacity for oxygen during exercise?

Increased blood viscosity

Increased oxygen solubility in blood

Decreased pulmonary capillary pressure

Increased surface area of capillaries (correct)

What is the composition of adult hemoglobin regarding its polypeptide chains?

4 beta chains

2 alpha chains and 2 beta chains (correct)

4 alpha chains

3 alpha chains and 1 beta chain

In what form is oxygen predominantly transported in the blood?

Bound to hemoglobin Signup and view all the answers

Which statement best describes what occurs when oxygen is released from hemoglobin in tissues?

Hemoglobin releases oxygen due to low tissue PO2 Signup and view all the answers

What happens to the oxygen saturation of blood as it passes through the pulmonary capillaries?

It becomes almost saturated Signup and view all the answers

What physiological change occurs to the oxygen-hemoglobin dissociation curve during exercise?

A rightward shift indicates decreased affinity for oxygen Signup and view all the answers

What factor is NOT associated with effective pulmonary gas exchange?

Low ambient oxygen concentration Signup and view all the answers

What is the PCO2 in the interstitial fluid surrounding tissue cells?

45 mm Hg Signup and view all the answers

How does a decrease in blood flow to peripheral tissues affect the PCO2 levels in those tissues?

PCO2 increases due to decreased removal of CO2 Signup and view all the answers

What is the approximate PCO2 of arterial blood that is entering tissue?

40 mm Hg Signup and view all the answers

Which factor primarily drives the diffusion of CO2 from the pulmonary capillaries into the alveoli?

Pressure differential of CO2 Signup and view all the answers

What happens to interstitial PCO2 when blood flow to peripheral tissues is increased sixfold?

It decreases to approximately 41 mm Hg Signup and view all the answers

What is the intracellular PCO2 in tissue cells?

46 mm Hg Signup and view all the answers

How does the PCO2 of venous blood leaving the tissue compare to arterial blood entering it?

Higher than arterial blood PCO2 Signup and view all the answers

In the context of pulmonary gas exchange, what is the approximate PCO2 of alveolar air?

40 mm Hg Signup and view all the answers

What is the primary effect of diffusion on blood PCO2?

It decreases the blood PCO2. Signup and view all the answers

What role does fetal hemoglobin play compared to adult hemoglobin regarding oxygen affinity?

Fetal hemoglobin has a higher affinity for oxygen. Signup and view all the answers

How does increased BPG in prolonged hypoxic conditions affect the oxygen-hemoglobin dissociation curve?

It shifts the curve to the right. Signup and view all the answers

What is the relationship between CO2 diffusion rates and O2 diffusion rates?

CO2 diffuses faster than O2. Signup and view all the answers

What does an increased hydrogen ion concentration indicate about oxygen delivery to tissues?

It inhibits oxygen delivery to tissues. Signup and view all the answers

During what distance into the capillaries does diffusion occur efficiently?

Within one-third of the capillary length. Signup and view all the answers

Which of the following is true about CO2 transport from tissues?

CO2 diffuses from cells into capillaries for transport. Signup and view all the answers

What is the result of oxygen being used by cells in terms of PCO2?

It causes an increase in PCO2. Signup and view all the answers

Study Notes

Diffusion and Oxygen Transport

Diffusion in the lungs lowers blood carbon dioxide (CO2) levels and reduces hydrogen ion concentration.
This shifts the oxygen-hemoglobin dissociation curve to the left and upward.
As a result, more oxygen binds to hemoglobin at any given alveolar oxygen partial pressure (PO2).
This facilitates greater oxygen transport to tissues.
Fetal hemoglobin binds to oxygen with higher affinity than adult hemoglobin.

Carbon Dioxide Transport

CO2 diffuses from tissues into capillaries and eventually to the lungs.
This process is about 20 times faster than oxygen diffusion.
During exercise, the diffusing capacity for oxygen increases almost threefold mainly due to increased capillary surface area and a more ideal ventilation-perfusion ratio.

Oxygen Transport in Blood

Oxygen is transported in blood in two forms:
- Dissolved in solution
- Bound to hemoglobin (most common form)
Hemoglobin is a globular protein with four subunits, each containing a heme moiety which is an iron-containing porphyrin.
- The iron is in the ferrous state (Fe2+) and binds to O2.
- Each subunit has a polypeptide chain:
  - 2 alpha chains
  - 2 beta chains

Oxygen-Hemoglobin Dissociation Curve

The curve shifts to the left when oxygen affinity increases (higher affinity for hemoglobin).
The curve shifts to the right when oxygen affinity decreases (lower affinity for hemoglobin).

Effect of Bisphosphoglycerate (BPG) on Oxygen-Hemoglobin Dissociation Curve

Normal BPG levels in blood slightly shift the oxygen-hemoglobin dissociation curve to the right.
During hypoxia, BPG levels increase, causing a further rightward shift.
This shift facilitates the release of O2 to tissues in conditions of lower oxygen availability.

Carbon Dioxide Transport: Diffusion and Pressure

The pressures of CO2 in the tissue, interstitial fluid, and blood are:
- Intracellular PCO2 = 46 mm Hg
- Interstitial PCO2 = 45 mm Hg
- Arterial Blood PCO2 = 40 mm Hg
- Venous Blood PCO2 = 45 mm Hg
There is a pressure difference of 5 mm Hg which drives CO2 diffusion from the pulmonary capillaries into the alveoli.

Influence of Blood Flow and Tissue Metabolism on Tissue Carbon Dioxide Pressure (PCO2)

Decreased blood flow leads to decreased blood flow and tissue PCO2 rises.
Increased blood flow leads to higher PCO2.
Tissue PCO2 is influenced by metabolic rate and blood flow.

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Description

Explore the intricate processes of oxygen transport and diffusion in the body. This quiz covers the mechanisms involved in both oxygen and carbon dioxide transport, and the differences between fetal and adult hemoglobin's affinity for oxygen. Test your understanding of these critical physiological processes.