ch+7+immune+system+review+DR

1. Bacteria are single-celled prokaryotes, and they do not have a nucleus. Five features that is has are the bacillus, the coccus, the spirillium, the capsule, and the pilus. 2. Viruses are acelluar, not composed of cells. They are alive because they can replicate. It is able to reproduce through replication. 3. A virus emerges by being transported from one location to another where it has not been before. 4. Prions are proteinaceous infectious particles. They cause a group of degenerative diseases of the nervous system. 7. Nonspecific defenses cannot distinguish between foreign and normal. 8. The first line of defense is the skin and mucous membranes. The skin is usually very effective physical barrier that prevents infection. Mucous membranes that line the respiratory, digestive, reproductive, and urinary tracts also serve as physical barriers. 9. The second line of defense is the inflammatory response. Histamine, mast cells, and pus are al examples of this. 10. B cells and T cells are involved in providing specific defense against pathogens 11. The clonal selection model states than an antigen selects, then binds to the BCR of only one type B cell and then this B cell produces multiple copies of itself 12. The basic unit that composes antibody molecules is a Y shaped protein molecule with two arms. There are five different classes of antibodies. The classes are IgG, IgM, IgA, IgD, and IgE 13. When a T cell leaves the thymus, it has a unique T-cell receptor.The types of T cells are the Cytotoxic T cells and the helper T cells. The Cytotoxic T cells fight the enemy directly while the helper T cells secrete cytokines 14. Active immunity develops naturally after a person is infected with a pathogen. 15. Every plasma cell derived from the same B cell secretes antibodies against a specific antigen. These are monoclonal antibodies.