Lymphoid Organs: Histology Mind Map

False (B)

True (A)

<p>It is composed of thymic epithelial cells (C)</p> Signup and view all the answers

<p>Medulla of the thymus (B)</p> Signup and view all the answers

<p>Secondary nodules have a germinal center. (B)</p> Signup and view all the answers

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

<p>To protect mucosal surfaces from pathogens (A)</p> Signup and view all the answers

<p>Primary lymphoid organs produce and mature lymphocytes, while secondary lymphoid organs are where lymphocytes encounter antigens and initiate immune responses.</p> Signup and view all the answers

<p>Desmosomes are protein complexes that connect cells tightly together, ensuring the structural integrity of the cytoreticulum.</p> Signup and view all the answers

<p>Tonsils are positioned in the pharyngeal region to provide early immune responses to pathogens that enter the body through the mouth or nose.</p> Signup and view all the answers

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

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

<p>Medullary cords are the inner region of lymph nodes where lymph flows and is filtered. They contain lymphatic sinuses and medullary cords.</p> Signup and view all the answers

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

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

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

<p>Hassall's corpuscles</p> Signup and view all the answers

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

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

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

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

<p>White Pulp</p> Signup and view all the answers

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

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

The primary site where all blood cells, including lymphocytes, are produced.

Stem cells in bone marrow give rise to all blood cells, including B-lymphocytes (B-cells) which mature within the marrow.

Primary lymphoid organs are responsible for producing and maturing lymphocytes. These organs include the bone marrow and the thymus.

T-lymphocytes (T-cells) are produced in the bone marrow, but they migrate to the thymus to mature.

The thymus is divided into two regions: the cortex and the medulla.

Immature T-cells proliferate in the cortex, while more mature T-cells reside in the medulla.

Hassall's corpuscles are unique structures within the medulla of the thymus, composed of concentric layers of epithelial cells that support T-cell development.

The thymus relies on a cytoskeletal structure called the cytoreticulum, formed by thymic epithelial cells, rather than traditional reticular fibers found in other lymphoid organs.

Thymic epithelial cells originate from the endoderm and are joined by desmosomes, protein complexes that connect cells tightly together.

Primary nodules are small, inactive clusters of lymphocytes without a germinal center, meaning they haven't been exposed to an antigen that triggers an immune response.

When lymphocytes in a primary nodule encounter an antigen, they proliferate and form a germinal center.

Secondary nodules are lymphatic follicles with a germinal center, indicating that B-cells have been activated by an antigen and are undergoing rapid proliferation and differentiation.

The germinal center is the area within a secondary nodule where B-cells rapidly proliferate, differentiate, and undergo somatic hypermutation to produce highly specific antibodies.

Lymphoid organs containing reticular fibers made from collagen that form a network to support lymphocytes, include lymph nodes, spleen, tonsils, and MALT.

Lymph nodes are encapsulated and divided into two main areas: the cortex and the medulla.

The cortex of a lymph node contains both primary and secondary nodules, while the medulla contains medullary cords and sinuses where lymph flows and is filtered.

The capsule of a lymph node is a dense layer of connective tissue surrounding it.

Tonsils are lymphoid tissues located in the pharyngeal region, protecting against pathogens entering the body via the mouth or nose.

The spleen is a secondary lymphoid organ that filters blood, not lymph, containing lymphocytes and is involved in immune responses to blood-borne antigens.

The spleen is divided into two main regions: the white pulp and the red pulp.

The white pulp contains lymphocytes and is involved in immune responses to blood-borne antigens, while the red pulp contains splenic cords and sinusoids where old or damaged red blood cells are filtered and removed from the blood.

MALT (Mucosa-Associated Lymphoid Tissue) is found in regions exposed to the external environment, such as the gastrointestinal tract (GALT) and respiratory tract (BALT).

MALT clusters immune cells within the connective tissue layers of mucous membranes to protect areas of the body that are often exposed to germs.

MALT does not have a connective tissue capsule like other lymphoid organs.