Anatomy II: Chapter 20

What are the two divisions of the lymphatic system?

Lymphatics (lymphatic vessels, lymph, lymph nodes) and lymphoid organs/tissues (spleen, tonsils, thymus, etc.).

What is the primary function of the lymphatic system?

Returns leaked fluids and proteins to the blood, transports fats, and plays a role in immune defense.

What are lymphatic capillaries?

Thin-walled, close-ended tubes that collect interstitial fluid

What makes lymphatic capillaries highly permeable?

Overlapping endothelial cells forming 'minivalves.'

What are lacteals?

Specialized lymph capillaries in the intestines that absorb digested fats (chyle).

What are the two main lymphatic ducts?

Right lymphatic duct (drains right upper arm, right head, and thorax) and thoracic duct (drains the rest of the body).

Where do lymphatic ducts empty?

Into venous circulation at the junction of the internal jugular and subclavian veins.

What propels lymph through lymphatic vessels?

Pulsations of arteries, vessel contractions, valves, and muscular/thoracic pumps.

What are the two main types of lymphocytes?

T cells (cell-mediated immunity) and B cells (produce antibodies).

What is the function of T cells?

Manage immune response and attack foreign cells.

What do B cells do?

Produce plasma cells that secrete antibodies.

What are the main functions of lymph nodes?

Filtration (destroying microbes and debris) and immune system activation.

What are the structural regions of a lymph node?

Cortex (contains B cells and dendritic cells) and medulla (contains B, T, and plasma cells).

What is the function of the spleen?

Lymphocyte proliferation, immune response, blood filtration, and RBC recycling.

What are the two areas of the spleen?

White pulp (lymphocytes) and red pulp (RBC and pathogen breakdown).

Can a person live without a spleen?

Yes, but they may be more susceptible to infections.

What is the function of the thymus?

Maturation of T cells; does not directly fight antigens.

How does the thymus change with age?

It is large in infants, grows until adolescence, then gradually atrophies.

What does MALT stand for?

Mucosa-associated lymphatic tissue.

Where is MALT found?

In the tonsils, appendix, Peyer’s patches, and bronchi.

What is the function of the tonsils?

Trap and remove pathogens entering through the pharynx.

What are the four types of tonsils?

Palatine, lingual, pharyngeal (adenoids), and tubal tonsils.

What are Peyer’s patches?

Lymphoid tissue in the small intestine that destroys bacteria and generates memory cells.

What is the role of the appendix in immunity?

It contains lymphoid tissue to prevent bacterial invasion and produce memory lymphocytes.

What is chyle?

Fatty lymph absorbed from the intestines.

What is lymphangitis?

Inflammation of lymphatic vessels.

What is lymphedema?

Swelling due to lymphatic obstruction.

What are buboes?

Swollen lymph nodes, often a sign of infection (e.g., bubonic plague).

What is a splenectomy?

Surgical removal of the spleen.

What do the tonsillar crypts do?

Trap bacteria and particles for immune response.

Where does the thoracic duct originate?

cisterna chyli in the abdomen.

What is the function of the bronchomediastinal trunk?

Drains lymph from the thoracic organs.

How is lymph moved without a central pump?

Via muscle contractions, arterial pulsations, and one-way valves.

What is the significance of memory lymphocytes?

They provide long-term immunity after infection.

What happens if the thymus fails to develop properly?

T cells may not mature properly, leading to immune deficiencies.

How do lymph nodes help in cancer detection?

They filter cancer cells, and swollen nodes may indicate metastasis.

Why are the palatine tonsils most often removed?

They are the largest and most frequently infected.

What is reticular connective tissue’s role in lymphoid organs?

It forms the structural framework for immune cell interactions.

Why do lymph nodes swell during infection?

Due to increased lymphocyte activity and trapped pathogens.

What would happen if the lymphatic system stopped functioning?

Fluid accumulation (edema), immune deficiencies, and nutrient transport issues.