Chapter 20 The Lymphatic System and Lymphoid Organs and Tissues

Describe the primary function of the lymphatic system.

To return fluids leaked from blood vessels back to the blood.

Define the four main parts of the lymphatic system.

They are a network of lymphatic vessels, lymph fluid, lymph nodes, lymphoid organs

Explain what lymph is composed of.

A clear-to-white fluid containing white blood cells and chyle

How do lymphoid organs and tissues contribute to the immune system?

It structural basis for the immune system by housing phagocytic cells and lymphocytes.

Describe the flow path of lymph through the lymphatic vessels.

It’s lymphatic capillaries → collecting lymphatic vessels → lymphatic trunks → lymphatic ducts.

Identify the two main lymphatic ducts.

Right lymphatic duct and the thoracic duct.

Explain the areas drained by the right lymphatic duct.

The right upper arm, right side of the head, and thorax.

What is the cisterna chyli?

Its an enlarged sac at the start of the thoracic duct found in about half of individuals.

Describe the mechanisms that propel lymph through the lymphatic system.

The milking action of skeletal muscles, thoracic pressure changes during breathing, valves to prevent backflow, arterial pulsations, and smooth muscle contractions in vessel walls.

Describe the effect of physical activity on lymph flow.

It increases the flow of lymph.

Explain what lymphangitis is.

Its the inflammation of lymphatic vessels caused by streptococcal or staphylococcal infection

Define lymphedema and its causes.

It severe localized swelling (edema) caused by blocked lymphatic return, often resulting from tumors or lymphatic removal during surgery.

List common treatments for lymphedema.

Controlling pain and swelling through exercise, massage, compression, and decongestion therapy.

Identify the two main types of lymphocytes and their functions.

T cells, which destroy infected cells, and B cells, which produce plasma cells that secrete antibodies.

What role do macrophages play in the lymphatic system?

It phagocytose foreign microorganisms and debris entering lymph.

"Describe the function of reticular cells in the lymphatic system."

"Reticular cells are supporting lymphoid cells that produce reticular fibers (stroma), providing scaffolding for immune cells."

"Which lymphocytes are responsible for producing plasma cells that secrete antibodies?"

"B cells are responsible for producing plasma cells that secrete antibodies."

"What are the primary lymphoid organs?"

"The primary lymphoid organs are red bone marrow and thymus, where T and B cells mature."

"Describe where T cells and B cells mature."

"B cells mature in the bone marrow; T cells mature in the thymus."

"Define secondary lymphoid organs."

"Secondary lymphoid organs are sites where mature lymphocytes first encounter antigens and become activated, including lymph nodes, spleen, and MALT."

"Explain the main functions of lymph nodes."

"Lymph nodes are secondary lymphoid organs that cleanse lymph and activate immune responses."

"Identify where lymph nodes are typically found in the body."

"Lymph nodes are clustered along collecting lymphatic vessels and are located near the body surface in the cervical, axillary, and inguinal regions."

"Describe the cell types found in the cortex of a lymph node."

"The cortex of a lymph node primarily contains B and T lymphocytes, with B cells mainly located in germinal centers."

"What types of cells dominate the medulla of lymph nodes?"

"The medulla of lymph nodes is primarily dominated by macrophages."

"Explain how lymph nodes can indicate cancer spread."

"Lymph nodes can become secondary cancer sites, often presenting as swollen but usually painless nodes, which helps distinguish cancerous nodes from those related to infections."

"Describe the location and size of the spleen."

"The spleen is a blood-rich organ about the size of a fist, located in the left abdominal cavity just below the stomach."

"What are the main functions of the spleen?"

"The main functions of the spleen include lymphocyte proliferation and immune surveillance, cleansing blood of aged blood cells and platelets, and storing breakdown products of red blood cells."

"Describe the blood vessels associated with the spleen."

"The splenic artery and splenic vein serve the spleen, entering and exiting at the hilum."

"Explain the additional roles of the spleen beyond filtering blood."

"The spleen stores iron from red blood cell breakdown, stores platelets and monocytes, and may produce fetal erythrocytes."

"Define the difference between red pulp and white pulp in the spleen."

"Red pulp removes old, damaged red blood cells and pathogens, while white pulp is involved in immune functions with lymphocyte maturation and differentiation."

"Identify the lymphoid organ that stores breakdown products of red blood cells."

"The spleen stores breakdown products of red blood cells, including iron."

"Describe the structure and function of tonsils as lymphoid organs."

"Tonsils are the simplest lymphoid organs with crypts that trap bacteria and foreign material."

"Explain the anatomical location of the tonsils."

"Tonsils form a ring of lymphatic tissue around the pharynx."

"Name the four types of tonsils found in the human body."

"The four types of tonsils are palatine tonsils, lingual tonsil, pharyngeal tonsil (adenoids), and tubal tonsils."

"Identify which tonsils are the largest and most commonly infected."

"Palatine tonsils are the largest and most commonly infected, located at the posterior end of the oral cavity."