BIOL 1080 Chapter Notes - Chapter 3: Respiratory Tract, Microorganism, Keratin

• School: University of Guelph
• Department: Biology
• Course: BIOL 1080
• Professor: David Dyck

Document Summary

Pathogens: bacterial, viruses, protozoans, fungi, parasitic worms, and prions (infectious proteins) that cause disease are pathogens. Cancer cells is a cell that was once a normal cell but because of it"s change in genes, can no longer regulate its cell division. Three lines of defense: first line of defense: keep foreign organisms or molecules out of body by physical and chemical surface barriers. Mucous and skin membranes form the 1st line. Physical barriers: dead cells form the tough outer layer of skin, cells are lled with brous proteins called keratin, which is resistant to toxins and harmful enzymes. Dead cells are replaced 1 million cells every 40 mins. Takes microbes with them as they ake off. Mucous lining of digestive tract and respiratory passages. Respiratory - cilia beat constantly moving contaminated mucus to the throat. Chemical barriers: sweat and oil wash away microbes. Acidity of the secretions slow bacterial growth, and oils contain chemicals that kill some bacteria.