BIOM 250n 1st Edition Lecture 15Outline of Last Lecture I. Concept of ImmunityII. Recognition III. CommunicationIV. Innate Immune CellsOutline of Current Lecture I. Lymphatic SystemII. Phagocytosis Current LectureI. Lymphatic Systema. Lymph: fluid derived from blood plasmai. Flows out of the blood vessels and bathes tissuesb. Lymph vesselsi. Act as a secondary circulatory systemii. Capillaries collect lymph from tissues through one way valvesiii. Form larger vessels and lymph nodesiv. Largest vessels pass lymph back onto circulationc. Lymphoid tissuei. Spread around respiratory, digestive, urinary and reproductive tractsii. Lymph nodes contain regions made up of T cells, B cells and macrophagesto monitor lymphiii. Spleen has lymphocytes and macrophages to monitor bloodII. Phagocytosisa. Phagocytosis: process of ingesting a microbe or other solid substanceb. Phagocyte: cell capable of ingesting bacteria or cell debrisi. Neutrophils: most common leukocyte—phagocyticii. Monocytes in bloodstream mature into macrophages in tissuesc. Starts with chemotaxis—which is a chemical attractionThese 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.i. Immune cells sense bacterial products, cell debris, and immune cell signalsii. They follow this chemical gradient to the site of infection/damaged. Adherence: the receptor-ligand interactioni. PAMP (pathogen associated molecular structures) bind to TLRs and activates ingestionii. If bacteria is coated by serum proteins—process called opsonization—then adherence is boostediii. Adherence also induces the cell to release cytokines that recruit immune cells to the site of damagee. Ingestion:i. Plasma membrane forms cell projections (pseudopods) to engulf the organismii. Membrane fuses to completely surround the item in a vesicle—the phagosomeiii. The phagosome membrane pumps in protons to lower the pHf. Digestion/Killing:i. The complete phagosome enters the cytoplasmii. Lysosomes fuse with its membrane and form the phagolysosome and releases lysosomal enzymes (digestive enzymes)iii. Enzymes digest lipids, proteins, nucleic acids, etciv. Indigestible material is released from the cellg. Microbial evasion of phagocytosis: i. Via structures: 1. Capsules like the glycocalyx inhibit adherence2. The chemical nature of the capsule inhibits adherence by the phagocytic cellii. Via toxins:1. Leukocidins lyse/kill phagocytic cells2. Pore-forming toxins help bacteria to break out of the phagosome so they are able to multiply in the celliii. Intracellular survival:1. Some bacteria have adapted to the low pH of the phagosome and are able to multiply inside of it2. Intracellular multiplication fills and then lyses the
View Full Document
Unlocking...