lymphatic system

Form and function of lymphatic system:

Form: Lymphoid organs and tissues

Function: Filter lymph

What are the lymphoid cells?

Lymphocytes, macrophages, dendritic cells, and reticular cells.

Function of lymphocytes:

Function: Main part of the immune system that attacks antigens.

Function of macrophages:

Function: Phagocytize foreign substances and activate t-lymphocytes.

What are dendritic cells?

Spiney-looking phagocytes.

Function of reticular cells?

Function: Provide support network.

What tissues and cells make up lymphoid tissue?

Reticular connective tissues with macrophages on outside and lymphocytes on inside.

Form and location of diffuse lymphatic tissue:

Form: Scattered reticular tissue elements.

Location: Almost all organs.

Form and location of lymphoid follicles:

Form: Unencapsulated solid bodies of reticular elements and cells.

Location: Lymph nodes.

What are lymphoid organs?

Encapsulated reticular elements and cells.

What are the lymphoid organs?

Lymph nodes, spleen, thymus, tonsils, and appendix.

What is the function of the thymus?

It causes t-lymphocytes to become immunocompetent and does not fight antigens.

Does the thymus have reticular fibers?

No, it has epithelial cells.

What are the components that make up the thymus?

There are two lobes called the cortex and medulla surrounded by a capsule that further subdivides them into lobules.

What tissue makes up the thymus capsule?

Dense irregular connective tissue.

What structure of the thymus capsule makes the lobules?

The septa which extends into the lobes.

What tissues and cells make up the cortex?

A large number of t-lymphocytes, macrophages, and reticular epithelial cells.

What is the function of the reticular epithelial cells in the thymus cortex?

They isolate t-lymphocytes and keep lymphocytes from antigens.

What structures and cells make up the thymus medulla?

Immunocompetent t-cells, reticular epithelial cells, and Hassall’s Corpuscles.

What do thymus epithelial cells do?

Produce hormones.

What supplies the thymus with blood?

Small arteries in the connective tissue and continuous capillaries in cortex.

What is the blood-thymus barrier?

T-cells do not contact macromolecules of blood.

What are the functions of lymph nodes?

They filter lymph using macrophages before it passes to bloodstream and activates immune system.

What are structures in lymph nodes?

They have a bean-shaped capsule made of dense fibrous CT, trabeculae which are extensions of the capsule, and cortex and medulla.

How does lymph circulate through lymph nodes?

It enters through the convex side, moves through the cortex to medulla, and then the flow stagnates which allows lymphocytes and macrophages to work.

What cells make up the lymph node cortex?

Reticular cells, b lymphocytes, and macrophages.

What is the lymph node paracortex?

Part between cortex and medulla.

What structures or cells does the lymph node paracortex contain?

T-cells and high endothelial venules.

Form and function of high endothelial venules:

Form: Cuboidal cells

Function: Allows for lymphocytes to leave vessels

What does the lymph node medulla contain?

Large lymph sinuses, lymphoid cells around sinus, and lymphoid cords (cell clusters).

What is the spleen?

The largest lymphoid organ on the left side of the abdominal cavity.

What is the function of the spleen?

Filters blood and stores platelets and breakdown products from blood cells.

What are some components of the spleen?

Thin, fibrous capsule, trabeculae, white pulp, and red pulp.

Where does the spleen get blood from?

Splenic artery and vein, hilus, and repeated vessel branching.

What are the different tonsils?

Palatine, lingual, pharyngeal, and tubal.

What are properties of the palatine tonsil?

It is the largest at the back of the oral cavity and is most commonly infected.

What do the tonsils do?

Remove pathogens entering mouth and traps bacteria and particles.

Is the tonsils fully encapsulated?

No.

What are tonsils?

Ring of lymphoid tissue around the pharynx that appear as swellings of mucosa.

What is the appendix?

A tubular offshoot of the first part of the large intestine with lots of lymph nodes.

What are Peyer’s patches?

Isolated clusters of lymph nodes similar to tonsils at the distal portion of small intestine.

What are bronchus-associated lymphoid tissue?

Tonsils.

What are gut-associated lymphoid tissue?

Peyers patches and appendix.

What are mucosa associated lymphoid tissue?

Nonencapsulated lymphocyte infiltration in mucosa.

What makes up the red pulp of spleen?

Splenic sinuses with fusiform endothelial cells, splenic cords of reticular fibers, and many macrophages.

What does the white pulp of the spleen contain?

Lymphoid nodules with b-cells, lymphatic sheath with t-cells, germinal centers, and marginal zones between white and red pulp.

What are germinal centers?

Areas of antigenic challenge.

What is the capsule of spleen made of?

Collaginous dense irregular CT, smooth muscle cells, elastic fibers, and outer simple squamous epithelium.