Lymphatic System Overview
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Questions and Answers

What is the primary role of the lymphatic system?

  • To transport oxygen in the blood
  • To produce red blood cells
  • To regulate body temperature
  • To drain wastes and support the immune system (correct)

Which of the following correctly identifies where T cells mature?

  • Lymph nodes
  • Bone marrow
  • Thymus (correct)
  • Spleen

What type of connective tissue primarily makes up the stroma in lymphoid tissues?

  • Elastic connective tissue
  • Reticular connective tissue (correct)
  • Dense regular connective tissue
  • Loose areolar connective tissue

What is contained in the parenchyma of lymphoid tissues?

<p>Lymphocytes (A)</p> Signup and view all the answers

Which of the following organ types is responsible for both the production and maturation of B and T cells?

<p>Both thymus and bone marrow (B)</p> Signup and view all the answers

What distinguishes primary lymphoid organs from secondary lymphoid organs?

<p>Primary organs are where B and T cells mature or are produced (A)</p> Signup and view all the answers

What shape do most lymph nodes resemble?

<p>Kidney-bean (C)</p> Signup and view all the answers

What is the composition of red bone marrow in adults?

<p>Clusters of hematopoietic islands and numerous adipocytes (C)</p> Signup and view all the answers

What type of connective tissue forms the capsule that envelopes the lobes of the thymus?

<p>Dense irregular connective tissue (A)</p> Signup and view all the answers

What is the primary function of hematopoietic stem cells?

<p>Create all blood cells of the body (D)</p> Signup and view all the answers

In the thymus, what is the main role of the stroma?

<p>To serve as a supporting network for developing T lymphocytes (B)</p> Signup and view all the answers

What happens to the thymus during puberty?

<p>It involutes and becomes smaller (C)</p> Signup and view all the answers

Which of the following best describes the cortex of the thymus?

<p>It is the outer, darker region (D)</p> Signup and view all the answers

What is a significant change that occurs in lymphoid organs as people age?

<p>More adipocytes present (B)</p> Signup and view all the answers

What condition can occur if the thymus does not function properly?

<p>Autoimmune diseases (B)</p> Signup and view all the answers

What is the medulla of the thymus characterized by?

<p>Containing more adipose tissue in adults (C)</p> Signup and view all the answers

What is the term used to describe the central tolerance induced during T cell maturation in the thymus?

<p>Central tolerance (D)</p> Signup and view all the answers

Which structure provides a framework for the developing T lymphocytes in the thymus?

<p>Reticular fibers (C)</p> Signup and view all the answers

What is the primary role of thymic interdigitating cells?

<p>To present self-antigens to T cells (C)</p> Signup and view all the answers

What happens to developing T cells in the thymus if they fail positive selection?

<p>They undergo apoptosis (A)</p> Signup and view all the answers

Which feature is characteristic of the medulla of the thymus?

<p>Presence of Hassall’s corpuscles (C)</p> Signup and view all the answers

What is the function of macrophages in the thymus?

<p>To eliminate apoptotic thymocytes (A)</p> Signup and view all the answers

How does aging affect Hassall's corpuscles in the thymus?

<p>They increase in number (D)</p> Signup and view all the answers

What is the consequence of T cells failing negative selection in the thymus?

<p>They undergo apoptosis and die (D)</p> Signup and view all the answers

Which structure in the thymus is primarily involved in the positive selection of T cells?

<p>Cortex (B)</p> Signup and view all the answers

What do lymph nodes primarily store and increase in response to an antigen?

<p>Lymphocytes (C)</p> Signup and view all the answers

Which of the following describes T cells that exit the thymus?

<p>Mature, immunocompetent, and self-tolerant (D)</p> Signup and view all the answers

What structure enters the lymph nodes to be filtered?

<p>Afferent vessels (D)</p> Signup and view all the answers

Which zone of the germinal center is characterized by quiescent B cells?

<p>Mantle zone (C)</p> Signup and view all the answers

Which process do T cells undergo if they successfully recognize a foreign substance?

<p>Become active and proliferate (A)</p> Signup and view all the answers

What is the primary function of lymph nodes?

<p>Filtering lymph for particulate matter and microorganisms (A)</p> Signup and view all the answers

What type of cells predominantly populate the outer cortex of lymph nodes?

<p>B cells (B)</p> Signup and view all the answers

Which cells are involved in the proliferation and differentiation of centrocytes?

<p>T-helper cells (B)</p> Signup and view all the answers

What is the main characteristic of centroblasts found in the dark zone of the germinal center?

<p>Highly mitotic cells (D)</p> Signup and view all the answers

In which part of the lymph node do B cells interact with follicular dendritic cells?

<p>Light zone (A)</p> Signup and view all the answers

Which of the following statements is true regarding secondary nodules in lymph nodes?

<p>They contain active follicles. (B)</p> Signup and view all the answers

What type of tissue primarily makes up the capsule of the lymph node?

<p>Dense irregular connective tissue (A)</p> Signup and view all the answers

Which type of cells are macrophages in the lymph nodes responsible for?

<p>Presenting antigens (A)</p> Signup and view all the answers

What is the primary cell type found in the medulla of the spleen?

<p>T cells (B)</p> Signup and view all the answers

What is the main function of the spleen related to red blood cells?

<p>Removes damaged and old RBCs (C)</p> Signup and view all the answers

Which component makes up the majority of the spleen's structure?

<p>Red pulp (B)</p> Signup and view all the answers

What is found in the marginal zone of the spleen?

<p>Transitional area between red and white pulp (A)</p> Signup and view all the answers

Which statement is true regarding the white pulp of the spleen?

<p>It contains a germinal center. (C)</p> Signup and view all the answers

Which structure covers the central artery in the spleen?

<p>Periarterial lymphatic sheath (PALS) (A)</p> Signup and view all the answers

Which cell types are predominantly found in the white pulp of the spleen?

<p>B and T cells (B)</p> Signup and view all the answers

What is the main feature of the spleen that differentiates it from other lymphoid organs?

<p>Kidney-bean shape (B)</p> Signup and view all the answers

What is the primary distinguishing feature of pharyngeal tonsils compared to palatine and lingual tonsils?

<p>Simple columnar epithelium (A)</p> Signup and view all the answers

Which type of epithelium characterizes the lingual tonsils?

<p>Simple squamous nonkeratinized (A)</p> Signup and view all the answers

Where are Peyer's patches primarily located within the gastrointestinal tract?

<p>Ileum (C)</p> Signup and view all the answers

Which cell type is specifically associated with antigen presentation in Peyer's patches?

<p>M-cells (A)</p> Signup and view all the answers

What structural feature is characteristic of the tonsillar crypts?

<p>Deep, branching invaginations (A)</p> Signup and view all the answers

Which area of the body is the appendix located?

<p>Lower right quadrant (D)</p> Signup and view all the answers

What type of tissue is primarily found in the lamina propria of the appendix?

<p>Areolar connective tissue (B)</p> Signup and view all the answers

What do the palatine and lingual tonsils share in terms of epithelial structure?

<p>Simple squamous nonkeratinized epithelium (D)</p> Signup and view all the answers

Flashcards

Lymphatic System Function

Drains waste and is part of the immune system; monitors body fluids for harmful substances.

Lymphoid Tissues Composition

Consist of stroma (supporting framework, mostly reticular connective tissue) and parenchyma (functional elements, mostly lymphocytes).

Primary Lymphoid Organs

Bone marrow and thymus; where lymphocytes (B and T cells) are produced and mature.

Bone Marrow Function

Creates B and T cells; B cells mature there.

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Thymus Function

Site where T cells mature. Majority of circulating lymphocytes are T cells.

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Secondary Lymphoid Organs

All lymphoid organs except the bone marrow and thymus.

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Lymphatic Vessels

Capillary-like structures that collect waste from blood vessels forming lymph.

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Lymph Nodes

Aggregates of lymph tissue, typically kidney-bean shaped, that filter waste.

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Hematopoietic stem cells

Cells that create all blood cells in the body.

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Capsule (Thymus)

Dense irregular connective tissue that envelops the lobes of the thymus.

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Trabeculae (Thymus)

Septa (septa = partitions) that incompletely subdivide thymus lobes into lobules, extending from the capsule.

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Lobules (Thymus)

Subdivisions of thymus lobes, containing cortex and medulla.

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Cortex (Thymus)

Peripheral, dark-colored region of thymus lobules.

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Medulla (Thymus)

Central, light-colored region of thymus lobules.

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T cell maturation (Thymus)

Process where T cells develop in the thymus and learn to distinguish the body's own cells from foreign cells.

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Central tolerance (Thymus)

Process occurring in the thymus preventing the immune system from attacking the body's own cells.

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Thymocytes (Thymus)

Cells developing in the thymus before becoming activated T cells.

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Thymus involution

Thymus shrinkage with age, primarily due to increase of adipocytes

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Thymus Cortex

The outer region of the thymus where positive selection occurs. This process ensures that developing T cells can recognize foreign antigens. Cells that pass this selection continue maturing, while those that fail undergo apoptosis.

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Positive Selection

A process in the thymus cortex where developing T cells are tested for their ability to recognize foreign antigens. Only T cells that can bind to self-MHC molecules survive and continue maturing.

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Thymic Interdigitating Cell

A type of cell found in the thymus cortex that presents self-antigens to developing T cells. This helps in the positive selection process.

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Thymus Medulla

The inner region of the thymus where negative selection occurs. This process ensures that mature T cells do not attack the body's own cells (autoimmunity). Cells failing this selection undergo apoptosis, while those that pass become mature, immunocompetent, self-tolerant but naïve T cells.

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Negative Selection

A process in the thymus medulla where mature T cells are tested for their ability to recognize self-antigens. T cells that bind strongly to self-antigens are eliminated to prevent autoimmunity.

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Hassall's Corpuscle

A defining feature of the thymus medulla, consisting of aggregates of epithelial reticular cells. They likely play a role in removing apoptotic thymocytes.

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Spleen Function

The spleen filters blood, removes and destroys old RBCs and platelets, stores blood, and contributes to lymphopoiesis.

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Spleen Location

The spleen is located in the upper left quadrant of the abdomen, posteriorly, with its hilum connected to the tail of the pancreas.

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Spleen Structure

The spleen is a kidney-bean shaped, encapsulated organ with trabeculae and distinct regions: red pulp and white pulp.

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White Pulp

The white pulp is composed of lymphoid nodules, periarterial lymphatic sheaths (PALS) containing T cells and central arteries, macrophages, dendritic cells, and germinal centers.

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Red Pulp

The red pulp consists of splenic cords of Billroth (reticular cells and fibers) and sinusoids (spaces) where RBCs reside.

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Medulla of Spleen

The medulla of the spleen is the innermost region containing medullary cords (dense lymphoid tissue) and sinuses. It's rich in plasma cells and B and T cells.

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Splenic Cords of Billroth

These cords are found in the red pulp and are composed of reticular cells and fibers that help filter blood and remove old RBCs.

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Splenic Sinusoids

These spaces within the red pulp are where old RBCs are removed, replaced by fresh ones, and act as a reservoir for blood.

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Lymph Node Structure

Lymph nodes have a convex surface with afferent vessels bringing lymph in and a concave surface (hilum) with efferent vessels carrying filtered lymph out.

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Primary Lymphoid Nodule

A primary nodule in a lymph node is composed of tightly packed, quiescent B cells. They appear intensely basophilic due to their tightly packed, dark staining nuclei.

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Secondary Lymphoid Nodule

A secondary nodule in a lymph node has a germinal center, the site of active immune responses. It has a lighter center (germinal center) and a darker outer mantle zone.

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Germinal Center: Mantle Zone

The mantle zone of a germinal center is composed of resting, non-activated B cells. It appears intensely basophilic due to tightly packed nuclei.

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Germinal Center: Follicular Dendritic Cells

Follicular dendritic cells reside within the germinal center and present antigens to B cells, aiding in their activation.

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Germinal Center: Light Zone

The light zone of a germinal center contains centrocytes, which are activated B cells that have encountered their antigen and express it on their surface. These cells are undergoing proliferation and differentiation.

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Germinal Center: Dark Zone

The dark zone of a germinal center contains centroblasts, highly mitotic B cells that are actively dividing and differentiating.

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Lymph Node Function

Lymph nodes filter lymph for particulate matter and microorganisms, acting as a first line of defense against infection. They also house lymphocytes and other immune cells, facilitating immune responses.

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Lymph Node Outer Cortex

The outer cortex of a lymph node contains small, non-cleaved lymphocytes that can differentiate into centroblasts and ultimately centrocytes.

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Lymph Node Paracortex

The paracortex of a lymph node is the region between the outer cortex and the medulla. It is primarily composed of T cells and is involved in T cell activation and immune responses.

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MALT: What is it?

Mucosa-associated lymphoid tissue; specialized secondary lymphoid organs scattered throughout mucosal linings of various organs.

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MALT: Tonsils

Large, irregular masses of lymph tissue in the mucosa of the posterior oral cavity and nasopharynx, forming the Waldeyer ring.

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Tonsil types

Pharyngeal (adenoid), Tubal (2), Palatine (2), Lingual. Each has unique features like crypt presence and epithelial type.

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Tonsil Crypts - What are they?

Deep, branching invaginations in the tonsil epithelium. Trap antigens and facilitate immune response.

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MALT: Peyer's Patches

Large, irregular masses of lymph tissue in the mucosa and submucosa of the ileum (small intestine). Look like large secondary follicles.

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What are M-cells?

Specialized epithelial cells atop Peyer's patches. Sample antigens from the gut lumen and present them to immune cells.

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MALT: Appendix - Where is it?

A blind sac extending from the cecum in the right lower quadrant, containing primary and secondary follicles.

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Appendix's role - Immune function!

Contains primary and secondary follicles in the lamina propria and submucosa. Contributes to immune response and gut health.

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Study Notes

Lymphatic System

  • Lymphatic system drains waste and is part of the immune system.
  • It monitors body surfaces and internal compartments for harmful substances.
  • Lymphocytes are the definitive cell type.

Lymphoid Tissues

  • Composed of stroma (supporting framework-reticular connective tissue) and parenchyma (functional elements, mostly lymphocytes).
  • Lymph tissues can be in nodules or diffused (not encapsulated).

Primary Lymphoid Organs

  • Bone marrow: location for B and T cell creation; B cells mature here.
  • Thymus: location where T cells mature.

Secondary Lymphoid Organs

  • Secondary organs include lymph nodes, spleen, tonsils, and MALT.
  • Lymph nodes filter lymph for pathogens and foreign substances.
  • Spleen filters blood.
  • Tonsils are located in the pharynx and help protect against pathogens entering the body.
  • MALT (mucosa-associated lymphoid tissue) protects mucosal surfaces.

Lymph Nodes

  • Lymph nodes are encapsulated and bean-shaped.
  • They contain lymphatic nodules (aggregates of lymphocytes).
  • Lymph nodes filter lymph, which is a fluid that circulates throughout the body.
  • Lymph nodes contain macrophages (cells that engulf foreign substances).

Spleen

  • The spleen is the largest lymphoid organ.
  • It filters blood, removing damaged red blood cells and pathogens.
  • It contains red pulp (for filtering red blood cells), and white pulp (similar to lymph nodes, containing lymphocytes which can proliferate in the presence of an antigen).

MALT (Mucosa-Associated Lymphoid Tissue)

  • MALT is a diffuse lymphatic tissue—meaning it's not encapsulated.
  • It protects mucosal surfaces, such as the lining of the digestive tract.
  • Includes tonsils (palatine, pharyngeal, lingual, tubal) and Peyer's patches located in the small intestine.
  • Peyer's patches and appendix filter out pathogens and have germinal centers containing specialized immune cells.

Thymus

  • The thymus is where T cells mature.
  • As people age, the thymus shrinks and becomes infiltrated with fat.
  • The thymus has an outer cortex and an inner medulla.
  • Thymic corpuscles are found in the medulla.

General Lymphoid Tissue

  • Hematopoietic cells generate all blood cells.
  • Lymphocytes in lymphoid tissue can proliferate and mature based on the encountering of antigens.
  • Lymphocytes with antigen specificity increase in number in the presence of the antigen.

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Lymphatics PDF

Description

This quiz covers the essential components of the lymphatic system, including its structure and function. Learn about primary and secondary lymphoid organs, the role of lymphocytes, and how the lymphatic system contributes to immune response. Test your knowledge on lymph nodes and lymphoid tissues.

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