Simple squamous epithelium refers to a single layer of thin, flat cells that line body surfaces. One side of the surface opens to the environment while the other is anchored to the underlying cells. These cells provide a thin membrane that allows for the passage of small molecules into the body, which occurs for example when air diffuses in the lungs; when blood is filtered to form urine in the kidneys; and when nutrients diffuse from the blood into body tissues in minute blood vessels called capillaries.
A simple squamous epithelium, called endothelium, lines the inner surfaces of arteries, veins and capillaries. In arteries and veins, endothelium reduces friction and allows for smooth blood flow. Endothelial cells in arteries and veins also aid in the constriction or dilation of the blood vessels, which regulates blood flow and pressure.
The walls of capillaries are composed of a single layer of endothelial cells. This allows for the easy exchange of nutrients and oxygen into the body tissues, and the removal of waste products.
- A simple squamous epithelium, called endothelium, lines the inner surfaces of arteries, veins and capillaries.
Causes of Low Blood Oxygen Levels
Simple squamous epithelium lines the air sacs, or alveoli, of the lungs 1. The alveoli are sites where air is exchanged in the lungs. Simple squamous epithelial cells in the alveoli allow oxygen from the air to enter the blood in the capillaries of the lung. Carbon dioxide, a waste product, passes across the epithelium of the alveoli to be removed from the body.
- Simple squamous epithelium lines the air sacs, or alveoli, of the lungs 1.
- Simple squamous epithelial cells in the alveoli allow oxygen from the air to enter the blood in the capillaries of the lung.
Simple squamous epithelial cells in the kidney enable rapid filtration of the blood and diffusion of small molecules. This process allows the kidneys to remove waste products and excess water from the body in the urine.
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- Tufts School of Medicine OpenCourseWare: Epithelium
- Robbins Pathological Basis of Disease; Ramzi Cotran, et al.
- Knudsen, L., and M. Ochs. The Micromechanics of Lung Alveoli: Structure and Function of Surfactant and Tissue Components. Histochemistry and Cell Biology. 2018. 150(6):661-676. doi:10.1007/s00418-018-1747-9
- Hsia C, Hyde D, Weibel E. Lung Structure and the Intrinsic Challenges of Gas Exchange. Comprehensive Physiology. 2016. 6(2):827-895. doi:10.1002/cphy.c150028
- Knudsen L, Ochs M. The micromechanics of lung alveoli: structure and function of surfactant and tissue components. Histochemistry and Cell Biology. 2018. 150(6):661-676. doi:10.1007/s00418-018-1747-9
- Trapnell BC, Nakata K, Bonella F, et al. Pulmonary alveolar proteinosis. Nature Reviews. Disease Primers. 2019. 5(1):16. doi:10.1038/s41572-019-0066-3
- Kasper, Dennis L.., Anthony S. Fauci, and Stephen L.. Hauser. Harrison's Principles of Internal Medicine. New York: Mc Graw Hill education, 2015. Print.
Leann Mikesh holds a Ph.D. in pathology. She has trained at the University of Virginia Medical Laboratories and has over 15 years experience in clinical, cancer and immunology research. Dr. Mikesh performed kidney and bone marrow transplantation compatibility testing to put herself through graduate school.