chapter20 lymphimmunemarieb

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Chapt 20: The Lymphatic Chapt 20: The Lymphatic and Immune Systems and Immune Systems Goals Goals 1. 1. Discuss the organization of the Discuss the organization of the lymphatic system, including the lymphatic system, including the vessels, principal lymph nodes, vessels, principal lymph nodes, thymus, and spleen thymus, and spleen 2. 2. Explain the relationship between the Explain the relationship between the lymphatic and circulatory systems, lymphatic and circulatory systems, and the role of lymphoid tissue and the role of lymphoid tissue structures and lymphocytes in the structures and lymphocytes in the body’s defense body’s defense 3. 3. An introduction to the Immune System An introduction to the Immune System

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Page 1: Chapter20 lymphimmunemarieb

Chapt 20: The Lymphatic and Chapt 20: The Lymphatic and Immune SystemsImmune Systems

GoalsGoals

1.1. Discuss the organization of the Discuss the organization of the lymphatic system, including the lymphatic system, including the vessels, principal lymph nodes, vessels, principal lymph nodes, thymus, and spleenthymus, and spleen

2.2. Explain the relationship between the Explain the relationship between the lymphatic and circulatory systems, and lymphatic and circulatory systems, and the role of lymphoid tissue structures the role of lymphoid tissue structures and lymphocytes in the body’s defenseand lymphocytes in the body’s defense

3.3. An introduction to the Immune SystemAn introduction to the Immune System

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Overview of the Overview of the Lymphatic SystemLymphatic System

Includes, vessels, fluid, and nodes Includes, vessels, fluid, and nodes or nonsecreting "glands". or nonsecreting "glands".

Lymphatic vessels convey fluid Lymphatic vessels convey fluid from the periphery to the veins. from the periphery to the veins.

The fluid, The fluid, lymphlymph (=clear water), is (=clear water), is what seeps out of the blood at what seeps out of the blood at the peripheral capillaries. the peripheral capillaries. Composition is similar to Composition is similar to plasma without as much plasma without as much proteinprotein

Fig 20.1Fig 20.1

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Overview of the Overview of the Lymphatic SystemLymphatic System

Lymphatic organs or tissues Lymphatic organs or tissues ("glands” is a misnomer) are ("glands” is a misnomer) are filtering areas and arenas of filtering areas and arenas of lymphocyte maturation and lymphocyte maturation and competency.competency.

Accessory to cardiovascular Accessory to cardiovascular system, thus there are two system, thus there are two drainage systems.drainage systems.

Fig 20.1

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1.1. Filtration of lymphFiltration of lymph

2.2. Return of leaked fluid Return of leaked fluid to cardiovascular to cardiovascular systemsystem

3.3. ““Education” and Education” and production of immune production of immune system lymphocytessystem lymphocytes

4.4. Transport of digested Transport of digested lipids from small lipids from small intestinal lactealsintestinal lacteals

Major Functions of Major Functions of the Lymphatic the Lymphatic SystemSystem

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Lymph CapillariesLymph Capillaries

Thin walled Thin walled endothelium endothelium (no BM) (no BM) with periodic one way with periodic one way valves. In general they valves. In general they parallel veins.parallel veins.

– Usually not visible on Usually not visible on tissue sectionstissue sections

Capillaries converge Capillaries converge into collecting vessels into collecting vessels

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Lymph CapillariesLymph Capillaries

Closed ends allow fluid Closed ends allow fluid flow inward onlyflow inward only

– Also bacteria, viruses, Also bacteria, viruses, cancer cellscancer cells

Pick up and recycle Pick up and recycle extra tissue fluid extra tissue fluid

The fluid flows to The fluid flows to lymph nodeslymph nodes

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Lymph Lymph CapillariesCapillaries

Everywhere, except for Everywhere, except for CNS, bone marrow, cornea CNS, bone marrow, cornea and cartilage.and cartilage.

(XS fluid in CNS becomes (XS fluid in CNS becomes part of CSF)part of CSF)

Special set of lymph Special set of lymph capillaries in villi of small capillaries in villi of small intestineintestine == LactealsLacteals– Fat AbsorptionFat Absorption– To liverTo liver

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Damaged valves or blockedlymph vessels edema

Lymphatic vesselsLymphatic vesselsComparable in structure to capillaries, Comparable in structure to capillaries,

and in turn, veins. Thin walls!and in turn, veins. Thin walls!

Hard to find in a general dissectionHard to find in a general dissection

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Lymph capillaries converge to become collecting vessels and end up as eitherThoracic duct or right lymphatic duct

Thoracic (left lymphatic) duct

Left subclavian vein

Right lymphatic duct

Right subclavian vein

Cysterna Chyli

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Lymphoid Lymphoid OrgansOrgans

1.1. Lymph NodesLymph Nodes1.1. TonsilsTonsils

2.2. ThymusThymus

3.3. SpleenSpleen

4.4. Bone MarrowBone Marrow1.1. Stem cellsStem cells

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1. Lymph Nodes1. Lymph Nodes~ 500 (~ 500 ( 1mm to 25 mm) 1mm to 25 mm)

Bean-shaped with hilus, cortex and Bean-shaped with hilus, cortex and medullamedulla

Several afferent vessels, one efferent Several afferent vessels, one efferent vessel vessel

Function: filterFunction: filter

Popular term “lymph gland” is Popular term “lymph gland” is misnomer. Why?misnomer. Why?

Contain lots of Lymphocytes, Contain lots of Lymphocytes, Macrophages and Plasma CellsMacrophages and Plasma Cells

Clinical application: Swollen lymph Clinical application: Swollen lymph nodesnodes

Fig 23.9

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Distribution of LNsDistribution of LNs

Cervical lymph nodes Cervical lymph nodes - drain head and neck- drain head and neck

Axillary lymph nodes Axillary lymph nodes - drain arms and breasts- drain arms and breasts

Popliteal lymph nodes - drain legsPopliteal lymph nodes - drain legs

Inguinal lymph nodes - drain lower limbInguinal lymph nodes - drain lower limb

Thoracic lymph nodes - drain thoracic visceraThoracic lymph nodes - drain thoracic viscera

Abdominal lymph nodes - drain pelvic regionAbdominal lymph nodes - drain pelvic region

Intestinal and mesenteric lymph nodes - drain Intestinal and mesenteric lymph nodes - drain abdominal visceraabdominal viscera

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TonsilsTonsils

Simple lymphoid Simple lymphoid organs organs – ““Lymph nodules”Lymph nodules”

In the mouth/pharynxIn the mouth/pharynx– Lingual tonsil on Lingual tonsil on

posterior aspect of posterior aspect of tonguetongue

– Palatine = adenoids, Palatine = adenoids, lateral pharynxlateral pharynx

– Tubal, behind Tubal, behind Eustachian TubesEustachian Tubes

Fig 21.3a, page Fig 21.3a, page 584584

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Lymphoid TissueLymphoid Tissue

Connective tissue is loaded with Connective tissue is loaded with lymphocyteslymphocytes

Lymphoid nodules Lymphoid nodules are are unencapsulatedunencapsulated clusters of clusters of lymphocytes (lymphocytes ( ~ 1mm). Found ~ 1mm). Found beneath epithelial lining of beneath epithelial lining of respiratory, digestive & urinary respiratory, digestive & urinary tracts, etc.tracts, etc.

Mucosa Associated Lymphatic Tissue Mucosa Associated Lymphatic Tissue (MALT) in GI tract(MALT) in GI tract– 5 tonsils5 tonsils– aggregate lymphoid nodules in aggregate lymphoid nodules in

small intestine (= Peyer’s small intestine (= Peyer’s patches)patches)

– appendix - walls contain lymphoid appendix - walls contain lymphoid tissuetissue

= adenoids

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2. 2. ThymusThymus

Location above heart, posterior to sternumLocation above heart, posterior to sternum

Divided into lobulesDivided into lobules

Only lymphoid organ that does NOT fight Only lymphoid organ that does NOT fight antigens, it functions as “T-cell academy” antigens, it functions as “T-cell academy”

Involution after pubertyInvolution after puberty

Epithelial cells produce thymic hormones, Epithelial cells produce thymic hormones, thymosin and thymopoetinthymosin and thymopoetin

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3. 3. SpleenSpleen

Largest lymphoid organ, located in LUQ

Soft and very blood rich

Red pulp sinusoids containing RBCs

white pulpwhite pulp lymphoid tissue

Major Functions:

1. Initiation of Immune response to antigens in blood

2. Removal of aged and defective RBCs, Fe salvaging

3. Reservoir for new RBCs

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4. Bone Marrow4. Bone Marrow

Mostly in red marrowFrom pluripotent stem cells

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Fig 23.7

Bone Marrow: Bone Marrow: LymphopoiesisLymphopoiesis

Lymphocytes are also Lymphocytes are also produced in thymus, produced in thymus, spleen and tonsilsspleen and tonsils

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Important example: Axillary Drainage

Drainage from breast and arm

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The Immune SystemThe Immune System

Neutrophil with Bacillus anthracis

The primary defense against The primary defense against diseasedisease– Infectious, especiallyInfectious, especially– SpecificSpecific

Centered around the activity Centered around the activity of lymphocytesof lymphocytes– Other cells, too.Other cells, too.

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LymphocytesLymphocytes

Agranulocytes - large nuclei and small amount of Agranulocytes - large nuclei and small amount of cytoplasm cytoplasm

Function in identification and inactivation/destruction Function in identification and inactivation/destruction of pathogensof pathogens

Types of LymphocytesTypes of Lymphocytes1.1. T CellsT Cells - cellular immunity - specific for previously - cellular immunity - specific for previously

identified pathogens. AKA “cytotoxic cells.”identified pathogens. AKA “cytotoxic cells.”

2.2. B CellsB Cells - humoral immunity – become plasma cells, - humoral immunity – become plasma cells, which produce antibodies specific to the antigen or which produce antibodies specific to the antigen or pathogen; memory cells for future exposurespathogen; memory cells for future exposures

3.3. NK (Natural Killer) cellsNK (Natural Killer) cells - non-specific, provide - non-specific, provide immunological surveillance, recognition of “non-self”immunological surveillance, recognition of “non-self”

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Antibodies (Ab)Antibodies (Ab)

AKA immunoglobulins (Ig)AKA immunoglobulins (Ig) Proteins produced by plasma Proteins produced by plasma

cells in response to a specific cells in response to a specific antigen (Ag)antigen (Ag)– Plasma cells are derived from B-Plasma cells are derived from B-

lymphocyteslymphocytes Antibodies [Ab] frequently Antibodies [Ab] frequently

measured as a diagnostic toolmeasured as a diagnostic tool– SerologySerology

IgG

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5 subclasses of Igs:5 subclasses of Igs:

1.1. IgG: main Ab (75%) in serum; + IgG: main Ab (75%) in serum; + main Ab during 2main Ab during 2oo response response

2.2. IgAIgA: main Ab in external secretions: main Ab in external secretions

3.3. IgE: main Ab in allergic reactionsIgE: main Ab in allergic reactions

4.4. IgMIgM: Ab on virgin B-cells; + main Ab : Ab on virgin B-cells; + main Ab during 1during 1oo response response

5.5. IgD: Ab on virgin B-cellsIgD: Ab on virgin B-cells

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Sunset on the Atlantic Ocean