Lymphatic System and Lymphoid Organs Quiz

Study Notes

Lymph nodes are encapsulated structures, often spherical or kidney-shaped, made of lymphoid tissue.
Main sources of lymphocytes are lymph nodes and bone marrow, vital for immune response.
Each lymph node has an outer cortex filled with lymph nodules and an inner medulla.
Found in axillary and inguinal regions, lymph nodes are most numerous in the thorax and abdomen.
Lymph nodules in the cortex contain B lymphocytes, essential for antibody production.
Size of lymph nodes decreases with age unless affected by inflammation or tumors.
They typically exist in groups connected by lymph vessels, enhancing immune function.

Capsule, made of dense connective tissue, envelops the node and projects trabeculae internally.
Outer Zone includes lymphoid nodules rich in B lymphocytes, important for immune responses.
Inner Zone (Paracortex) consists of diffuse lymphoid tissue, populated mainly by T lymphocytes.
Sinuses in the Cortex consist of macrophages and reticular fibers, facilitating lymph filtration.
Subcapsular Sinus receives lymph from afferent lymphatic vessels and lies beneath the capsule.
Intermediate Sinuses are adjacent to trabeculae and channel lymph into medullary sinuses.

Composed of medullary cords containing extending B lymphocytes from the inner cortex.
Medullary Sinuses continue from intermediate sinuses to facilitate lymph flow into efferent vessels.
Small arteries enter at the hilum to supply the outer cortex, where high endothelial venules (HEVs) are formed.

Axillary Lymph Nodes drain lymph from the upper limb and breast, leading to the subclavian lymph trunk.
Inguinal Lymph Nodes receive lymph from lower limbs, draining into external and common iliac nodes.
Cervical Lymph Nodes collect lymph from the head and neck, crucial for localized immunity.

Cisterna Chyli serves as a major drainage point for the abdomen.
Thoracic Duct collects lymph from the cisterna chyli, left upper limb, and left head/neck area.
Right Lymphatic Duct drains the right upper quadrant of the body.
Mesenteric Lymph Nodes form a central system for lymph from mesenteric area's nodes.
Bronchomediastinal Lymph Nodes receive lymph from tracheobronchial and mediastinal regions.

Located in the upper left abdominal quadrant, the spleen is encased in a capsule of dense connective tissue.
Trabeculae penetrate the spleen, housing larger blood vessels supplying its internal structure.

White Pulp, identified by its whiteness in fresh specimens, is comprised of periarterial lymphoid sheath (PALS) and surrounding T lymphocytes.
Lymphoid Nodules containing B lymphocytes are distributed within the PALS.

Largest collection of lymphoid tissue, the spleen uniquely filters blood and defends against blood-borne antigens.
Primary site for the destruction of old erythrocytes, facilitating recycling of iron and hemoglobin.
Produces antibodies and activated lymphocytes, which are released into circulation.

Surrounded by a dense connective tissue capsule, which sends trabeculae into the splenic pulp.
Filled with reticular tissue containing reticular cells, fibers, different blood cells, macrophages, and antigen-presenting cells.
Splenic pulp consists of white pulp (20%) primarily for immune functions and red pulp for blood filtration and storage.

The spleen monitors blood immunologically, with specialized microvasculature.
Unique regions within the microvasculature enhance early detection and response to pathogens.
Trabecular arteries branch from the hilum, leading into the parenchyma populated by T cells, macrophages, and plasma cells.

The spleen represents the largest accumulation of lymphoid tissues found within the abdominal cavity.
It serves as a critical site for the destruction of aged red blood cells, maintaining healthy blood circulation.