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Chapter 16 Lecture 1 (Properties of Antigens (Most effective are large…
Chapter 16 Lecture 1
Properties of Antigens
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Molecule’s shape, size, and complexity make certain molecules more effective at provoking adaptive immunity.
Our body recognizes antigens by three-dimensional shapes of regions called epitopes(also known as antigenic determinants).
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Large molecules with molecular masses(sometimes misidentified as molecular weights) between 5,000 and 100,000 Daltons are better antigens than smaller ones.
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Molecules under mass of 5,000 daltons, make poor antigens. They can become antigenic when bound to larger carrier molecules.
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Lymphoid Organs
When lymphocytes mature in the primary lymphoid organs (red bone marrow and thymus), they go to secondary lymphoid organs and tissues (lymph nodes, spleen, and less organized tissues of lymphoids
Each lymph node receives lymph from afferent or inbound vessels and lymph from 1-2 efferent or outbound vessels
The lymph node has a medulla or middle consisting of a maze of passages that filters the lymph as it goes through
Houses many lymphocytes that survey the lymph for foreign molecules and create specific immune responses against them
The outer portion of a lymph node consists of a capsule surrounding primary follicles where B cells replicate
The lymphatic system has secondary lymphoid tissues and organs like the spleen, tonsils, and mucosa associated lymphoid tissue (MALT)
The spleen works like the lymph nodes except it filters blood. It removes bacteria, viruses, toxins, and other foreign matter in blood. It also cleans blood of old and damaged blood cells, stores blood platelets, and blood components
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Adaptive immunity
Adaptive immunity is a vertebrate’s ability to recognize and then mount a defense against distinct invaders and their products, whether they are protozoa, fungi, bacteria, viruses, or toxins.
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Immunologists (scientists who study the cells and chemicals involved in immunity) are continually refining and revising our knowledge of adaptive immunity
Tonsils and MALT
Tonsils are on both sides of the tongue and work like the lymph nodes but they don’t have afferent or efferent vessels. These sample microbes that enter the mouth or nose.
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These both do not have an outer capsule like the lymph nodes or spleen but act the same way. They trap foreign particles and microbes that enter the body.
Types of Antigens
Exogenous antigens: come from outside the body's cells and include toxins and other secretions and components of microbial cell walls, membranes, flagella, and pili.
Endogenous antigens: protozoa, fungi, bacteria, and viruses that reproduce inside a body's cells produce endogenous antigens. The immune system cannot access the internal health of the body’s cells; it responds to endogenous antigens only if the body’s cells incorporate such antigens into their cytoplasmic membranes, leading to their external display.
Autoantigens: antigenic molecules drive from normal cellular processes are autoantigens (or self antigens). As we will discuss more fully in a later section, immune cells that treat autoantigens as if they were foreign are normally eliminated during the development of the immune system. This phenomenon, called self-tolerance, prevents the body from mounting an immune response against itself.
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Lymph Nodes
Located at various points of the body but are most concentrated in the neck, groin, armpit, and abdominal area
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Antigens
Adaptive immunity responses are directed not against whole bacteria, fungi, protozoa, or viruses but instead against portiins of cells, viruses, and even parts of single molecules.
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