The Lymphatic System & Immune Response Exercise 35 The Lymphatic System & Immune Response

Objectives Components & functions of lymphatic system Roles of B-cells, T-cells Structure & function of lymph nodes Localization of T-cells, B-cells, macrophages in lymph nodes Antigen vs. antibody Immunological memory, specificity, differentiation of “self vs. nonself”

Lymphatic System Cells, tissues, & organs responsible for defending the body against Environmental hazards (pathogens) Internal threats (cancers)

Lymphatic System Lymphocytes are primary cells responding to specific threats “specific defense” is the immune response

Lymphatic System Lymph (fluid c.t.) Lymphatic vessels Lymphoid tissues Tonsils Lymphoid organs Lymph nodes, thymus, spleen Fig. 22-1

Lymphatic System Functions Transports LYMPH to the blood (lymphatic capillaries pick up this “leaked” interstitial fluid from tissues & takes it to the veins) Fig. 22-2

Lymphatic System Functions Protects the body: Removes foreign material (i.e.: bacteria) from lymphatic system “Police” of the body fluids Replication/cell division of lymphocytes (T-cells, B-cells, etc.)

Lymphatic Vessels Right lymphatic duct SEE MODELS!!! Drains lymph from upper right extremity, head, thorax Into Rt Subclavian Vein Fig. 22-4

Lymphatic Vessels Thoracic duct Drains lymph from rest of the body Into L subclavian vein Fig. 22-4

Lymphatic Vessels Rt lymphatic & thoracic ducts Both empty lymph into venous circulation of blood One-way system—only TOWARD the heart Fig. 22-4

Lymphatic Vessels Cisterna chyli Enlarged inferior “end” of thoracic duct Receives lymph from the digestive viscera Fig. 22-4

Lymph Nodes Filter lymph as it’s transported through the lymphatic vessels 1000s throughout the body Macrophages inside—phagocytize bacteria, cancer cells, etc. in lymph before entering bloodstream Cervical, axillary, inguinal regions; Peyer’s patches in intestine

SEE MODELS!!! Fig. 22-1

clusters of lymph nodules in small intestine Peyer’s patches clusters of lymph nodules in small intestine SEE MODELS!!! uhaweb.hartford.edu/ BUGL/immune.htm

Structure of Lymph node Fig. 22-7

Peyer’s patch histology Collection of lymphoid nodules in mucosa of small intestine Peyer's Patches are largish, rounded areas located in the submucosa. They can be a bit difficult to spot: look for the slightly darker, purpler color and more speckled or grainy texture. Lumen of small intestine http://www.uky.edu/LCC/BSN/BIO/BiologyLabs/BSL111/111Lab6/Lab6DigestiveSlides.html

Lymph node histology http://science.nhmccd.edu/biol/lymphatic/lymph.htm

Lymphoid Tissue Tonsils Lingual Palatine Pharyngeal (adenoids) (2) Base of tongue Palatine L, R: posterior inferior palate Pharyngeal (adenoids) (1) posterior superior wall of nasopharynx Fig. 22-6 SEE MODELS!!!

Lymph Organs Thymus: primary lymphoid organ SEE MODELS!!! Fig. 22-8

Lymph Organs Spleen: secondary lymphoid organ SEE MODELS!!! Fig. 22-9

Lymphocytes: 2nd-most abundant WBCs Fig. 22-15

Stem Cells originate in bone marrow B cells Differentiate in bone marrow T cells Differentiate in thymus Then enter blood stream with specific things on cell’s surface, and are cloned in lymph organs

Fig. 22-15

Lymphocytes, continued: After cloned and made many more replicates, each can form memory cells or effector/regulatory cells

Lymphocytes, continued: B cell clones: Memory B cells Antibody-producing plasma cells “humoral immunity” (work indirectly through antibodies released into blood/lymphstreams

Lymphocytes: T cell clones: Memory T cells Cytotoxic T cells (directly attack virus-infected tissue cells) Helper T cells (activate B cells & cytotoxic T cells) Suppressor cells (can inhibit immune response) “cellular immunity” (act directly, attack bacteria/viruses/parasites/cancer cells)

“FILTER”: ~99% of antigens are removed before enters bloodstream Regions of T and B cells in lymph nodes Macrophages in Fig. 22-7

Antigen (Ag) vs. Antibody (Ab) Antigens Provoke an immune response ANTI body GEN erators Antibodies (immunoglobulins—Igs) Produced by sensitized B cells or plasma cells in response to antigen presence (proteins; IgM, IgG, IgD, IgA, IgE) Antigen-binding site is specific

Fig. 22-21

Important Immune Response Characteristics Immunological Memory Remembers foreign antigens it’s previously encountered, can react faster 2nd time (i.e.: chicken pox) Specificity Memory and antibodies very specific Differentiation of “self” and “non-self” Self = our own tissues, don’t alert immune response non-self = foreign antigens, triggers immune response

Important Immune Response Characteristics Just FYI--- Differentiation of “self” and “non-self” Can malfunction Autoimmune diseases (MS, Lupus, rheumatoid arthritis, juvenile diabetes, etc.)