Gas Exchange and Transport

These flashcards cover key concepts related to gas exchange and transport discussed in the lecture notes.

What is the primary function of respiration?

To exchange oxygen (O2) and carbon dioxide (CO2) between the body and the atmosphere.

What determines the alveolar gas tensions?

Alveolar CO2 tensions (PAC2) are determined directly by the body's production of CO2 (VC2) and inversely by alveolar ventilation (VA).

How is total oxygen content in the blood calculated?

Total oxygen content (CaO2) = (0.003 x PaO2) + (1.34 x Hb x SaO2) where PaO2 is the partial pressure of O2, Hb is the hemoglobin concentration, and SaO2 is the arterial oxygen saturation.

What is the significance of the V/Q ratio in the lungs?

The V/Q ratio reflects the balance between ventilation (V) and perfusion (Q) in the lungs; a ratio of 1 indicates perfect matching.

What is hypoxemia?

A condition in which there is insufficient oxygen in the blood (PaO2), potentially leading to hypoxia in tissues.

Describe the mechanism of carbon dioxide transport in the blood.

CO2 is transported in the blood in three forms: dissolved in plasma (7-10%), chemically bound to hemoglobin (carbaminohemoglobin - 20-23%), and as bicarbonate ions (approximately 70%).

Explain the B"""" effect on hemoglobin saturation.

The Bohr effect describes how a decrease in blood pH (increase in acidity) causes hemoglobin to release oxygen more readily.

What factors affect the loading and unloading of oxygen from hemoglobin?

Factors include pH, temperature, CO2 concentration, and presence of 2,3-Diphosphoglycerate (2,3-DPG) in red blood cells.

What are right-to-left shunts in the pulmonary circulation?

Right-to-left shunts occur when some blood bypasses the lungs and does not get oxygenated, reducing arterial oxygen content.

How does diffusion occur in gas exchange?

Diffusion of gases occurs from areas of higher partial pressure to areas of lower partial pressure across the alveolar-capillary membrane.

What is the impact of gravity on pulmonary perfusion and ventilation?

Gravity causes greater perfusion at the lung bases than at the apexes, affecting the V/Q ratio and gas exchange efficiency.

Define the term 'physiologic dead space.'

Physiologic dead space refers to the volume of air that does not participate in gas exchange due to inadequate perfusion or ventilation.

What is the role of the chemoreceptor in regulating respiratory function?

Chemoreceptors detect changes in blood gas levels (O2, CO2) and pH to regulate respiratory rate and depth for maintaining homeostasis.

What is the significance of anatomical shunts?

Anatomical shunts are parts of cardiac output that return to the left heart without being oxygenated in the lungs, impacting overall oxygen delivery.

How is oxygen affinity of hemoglobin affected by pH?

As pH decreases (more acidic), the affinity of hemoglobin for oxygen decreases, facilitating oxygen release to tissues.

Describe how cardiac output impacts oxygen delivery (DO2).

Oxygen delivery (DO2) is a function of cardiac output (CO) and arterial oxygen content (CaO2); reduced CO can lead to inadequate oxygen delivery.

What is the impact of elevated carbon dioxide levels on respiratory rate?

Elevated CO2 levels typically stimulate an increase in respiratory rate to enhance CO2 elimination and restore normal acid-base balance.

Outline the effects of aging on arterial oxygen tension (PaO2).

As individuals age, PaO2 generally decreases, leading to an increased risk of hypoxemia in older adults.

What condition can lead to impaired carbon dioxide removal?

Conditions such as restrictive lung diseases, ability to ventilate effectively, or variations in V/Q ratios can impair CO2 removal from the body.

What is the physiological significance of the saturation of hemoglobin with oxygen?

Hemoglobin saturation indicates how effectively oxygen is transported in the blood; low saturation can lead to hypoxia in tissues.

Explain the link between carbon dioxide levels and acid-base balance in the body.

Carbon dioxide levels influence the acidity of the blood; increased CO2 leads to acidosis, while decreased CO2 leads to alkalosis.

What is 'dysxia' and how is it different from hypoxemia?

Dysxia refers to impaired cellular uptake of oxygen, while hypoxemia is related to low oxygen levels in the blood.