The Wide World of Cells Cedars-Sinai Skip to content Close Select your preferred language English عربى 简体中文 繁體中文 فارسي עִברִית 日本語 한국어 Русский Español Tagalog Menu Close Call 1-800-CEDARS-1 toggle search form Close Share Email Print discoveries magazine Discoveries The Wide World of Cells Jun 01, 2022 Victoria Pelham, Illustrations: Marc Rosenthal Share Tweet Post There are more cells in the human body than stars in the Milky Way, each with a unique role in vital functions—from breathing to growing and eating. While the roughly 200 cell types work together, they follow different playbooks and routinely change casts. This cellular diversity is underappreciated, says Lali Medina-Kauwe, PhD, co-director of the Cancer Biology Program. "Structures are organized very intricately in and around cells, supporting all of the travel and various processes underway," she says. Here are a few of the most fascinating cellular factoids. Clean-Up Crew Macrophages Macrophages are the body’s biggest eaters. They overwhelm and kill off bacteria and then clear dead cells and tissue debris. If overactivated, though, macrophages can trigger inflammatory disease and cancer growth. "They can be heroes or villains," says Cedars-Sinai immunologist Helen Goodridge, PhD, who notes that macrophages are one of her favorite cells. Long-Distance Runners Neurons Neurons are the longest cells, with the lengthiest stretching nearly 5 feet down the spinal cord. Aided by motor proteins, these nerve cells transmit electrochemical messages that create movement, thought and sensations, including pain. They go the distance in age too: Brain neurons can last an entire human lifespan and, theoretically, even longer. Compare that to the lifespan of heavily worked gut epithelial cells (three to five days) or pancreatic cells (one year). Renewable Resource Skin Cells Skin is constantly shedding and being replenished. The human body sloughs off 200 million dead cells from the skin’s outer layer every hour (almost 5 billion a day), replacing the skin entirely every 40 to 56 days. While the roughly 200 cell types work together, they follow differing playbooks and frequently change casts." Frequent Fliers Red Blood Cells About 70% of the human body’s cells—25 trillion—are red blood cells, or erythrocytes, making them the most common. That vast supply is critical to life: Tiny erythrocytes continuously ferry oxygen from the lungs throughout the whole body. The hemoglobin protein is what paints blood its trademark red. Talent Development Stem Cells Found in embryonic and certain adult tissues, stem cells have not yet specialized. These prolific cells are at the heart of regenerative medicine, with their potential to be manipulated into immune, bone, skin, nerve or muscle cells. There is evidence that, in certain circumstances, just one hematopoietic stem cell in the bone marrow could regenerate and sustain an individual’s entire blood supply, including red blood cells and more than a dozen types of immune cells, Goodridge notes. Tags discoveries News and Notes Research Summer 2022 Share Tweet Post Blog & Magazines catalyst Blog & Magazines Home CS-Blog Blog CS Magazine Cedars-Sinai Magazine discoveries magazine Discoveries Magazine Embracing our Community Embracing Our Community Blog & Magazines catalyst Blog & Magazines Home CS-Blog Blog Embracing our Community Embracing Our Community CS Magazine Cedars-Sinai Magazine discoveries magazine Discoveries Magazine Popular Topics Patients Scientists Innovations Quick Reads Weird Science Make an Appointment Find a Doctor Schedule a Callback Call us 24 hours a day 1-800-CEDARS-1 Support Cedars-Sinai MAKE A GIFT VOLUNTEER Share Email Print Please ensure Javascript is enabled for purposes of website accessibility