Biol-M200 1st Edition Lecture 12 Outline of Last Lecture I. N/A- Exam #2Outline of Current Lecture II. 3 Lines of DefenseIII. Complement Systema. Classical Pathwayb. Alternative Pathwayc. Lectin PathwayIV. InterferonsCurrent LectureI. Species Resistancea. Protects humans from the pathogens of most other animals. II. The body’s 3 lines of defensea. First: external physical and chemical barriers to entryi. Skin: two major layers (Dermis and epidermis)ii. Skins chemical defenses: Perspiration (ex. Salt, dermicidins, lysozyme),sebum (oily substance; lowers the pH of the skin)iii. Mucous membranes: lines all body cavities open to the outside environment. iv. Tears: produced and drained by the lacrimal apparatus.b. Second: operates when pathogens succeed in penetrating the skin or mucousmembranes. (not physical barriers- cells, chemicals, processes)i. Blood: Leukocytes (white blood cells)- involved in defending the body against invaders.1. Granulocytes: contain large granules that stain different colors when viewed under the microscope. 2. Agranulocytes: cytoplasm appears uniform (no granules), monocytes- kidney shaped nucleus, mature into macrophages.Lymphocytes- involved in adaptive immunity.ii. Macrophages: phagocytic cells of the second line of defense. They arenamed by location in the body.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1. Wandering macrophages: move throughout the body, leave blood via diapedesis.2. Fixed Macrophages: often dwell within a specific organ, alveolar macrophages (lungs) and microglia (central nervous system).III. Complement Systema. Consists of a number of proteins in the blood. b. Provides a signal in the form of opsonins for phagocytes.c. Triggers inflammation and fever.d. Classical Pathway: activation of the pathway is dependent on antibody binding to foreign cells.e. Alternative Pathway: activation occurs independent of antibody binding to foreign cells.f. activation occurs when lectins bind to specific sugar molecules on surfaces of foreign cells.IV. Classical pathwaya. Consists of a series of chemical reactionsb. Product of a reaction will become an enzyme that catalyzes the next reaction.V. Alternative pathwaya. Initiated by the cleavage of C3 into C3a and C3bb. Occurs naturally at a slow rate in the plasma.c. Pathway does not proceed unless C3b recognized a pathogen then it is stabilized.d. Begins complement cascade leading to formation of MACs.VI. Lectin Pathwaya. Many bacteria, fungi, and viruses posses the sugar mannose on their surfaces. (mannose is rare in mammals)b. The human liver produces lectins that bind to mannose c. Trigger complement cascade beginning with cleavage of C2 and C4.Interferons: Proteins released by host cells that nonspecifically inhibit the spread of viruses. (Produced by infected host cells for the protection of neighboring cells).Inflammation: A nonspecific response to tissue damage characterized by redness, heat, swelling, and