Human Phys Alveoli, COVID-19 and UWI: Lung Anatomy, Ventilation and Perfusion

Type 1 alveolar cells

Simple squamous epithelial cells are the site of gas exchange

Type 2 alveolar cells

Regulate fluid balance and produce pulmonary surfactant, which functions to reduce fluid tension

Alveolar macrophages

Phagocytes of the respiratory system

Pulmonary capillaries

Surround alveoli and are short with high surface area (125 m^2)

Erythrocytes

These cells travel through the pulmonary capillaries in 0.5 seconds

O2/CO2

___exchange MUST occur rapidly to maintain effective respiration.

Pressure differentials

Diffusion across alveolar epithelium occurs due to what (Po2= 65mmHg, Pco2= 5mmHg)

Venous blood

PvO2= 40mmHg, PvCO2= 45mmHg

Alveolar air

PaO2= 105mmHg, PaCO2= 40mmHg

Arterial blood

PaO2= 100mmHg, PaCO2= 40mmHg

Heterogenous lung damage, acute lung inflammation, pleural effusion, cytokine storm, acute respiratory distress syndrome, dyspnea, hypoxemia, hypercapnia, thrombosis, multiorgan failure

Morbidity and mortality in COVID-19 results from

Pleural effusion

Fluid/proteins in the lungs

Slow death

20 days after initial diagnosis and 9-11 days in ICU in COVID-19 results in

Type 1 alveolar cell pathology

Epithelial Hemorrhaging, proliferation of collagen scar tissue fibrosis, thickening of endothelial walls, extensive impairment of O2/CO2 exchange occurs with what alveolar cell pathology

Proliferation of collagen scar tissue fibrosis, thickening of endothelial walls

What slows the rate of diffusion?

Hypoxemia

What has a PaO2 of 68 to 78mmHg; p<0.0001; normal = 100mmHg

Hypercapnia

What has a PaCO2 more than 46.1mmHg; p<0.0001; normal = 40mmHg

Left shift

Which shift (left or right) has an increased affinity for O2, decreased pCO2, decreased H+ ions, decreased 2,3-DPG, decreased temp.

Right shift

Which shift (left or right) has a decreased affinity for O2, increased pCO2, increased H+ ions, increased 2,3-DPG, and increased temp.

O2 during hypoxia

Increased pCO2, increased H+ ions, and increased temp decreases the loading of what

Type 3 alveolar cells pathology

Which alveolar cell type pathology has hemorrhaging, reduced surfactant, production, atypical hyperplasia, pulmonary edema, formation of hyaline membrane (fibrosis)

Hyperplasia

Increased in cell number

Hypertrophy

Increased in cell size

Alveolar macrophage pathology

Increase in alveolar macrophages stimulate an increase in neutrophils and the cytokine storm immune response which damages healthy cells and tissues in the heart, kidney, liver and testicles

Cytokine storm

The immune system attacks healthy cells (type 2 alveolar cells), not just those infected by SARS-Cov-2 also known as excessive immune response

Micro thrombosis

Aggregations of fibrin, cellular debris, erythrocytes and platelets that lead to the damage of the heart, kidneys, liver and the sertoli cells of the testicles (36% of severe cases disrupt spermatogenesis

Changes the surface, become thicker, may not increase

How does micro-thrombosis affect platelets