A&P II Chapter 20: The Lymphatic System .

What are the three main components of the lymphatic system?

Network of lymphatic vessels, lymph nodes , and lymph.

What is the primary function of lymph tissue in the lymphatic system?

Provide the structural basis of the immune system by housing phagocytic cells and lymphocytes. 

What direction does lymph ( vessels) flow in the lymphatic system?

one-way system toward the heart.

Where/what vessels drain into the venous circulation 

Right lymphatic duct and thoracic duct

What drains into the right lymphatic duct?

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

What drains into the thoracic duct?

The rest of the body

What is the primary role of lymphatic capillaries?

To absorb excess interstitial fluid and drain into larger lymphatic vessels.

What is the difference between lymphatic capillaries and regular capillaries?

Capillaries exchange materials while lymphatic capillaries absorb excess interstitial fluid. 

What is the difference between lymphatic arteries and arteries?

Arteries carry blood away from the heart while lymphatic vessels carry fluid toward the heart. 

What is the difference between lymphatic veins and veins?

Veins transport deoxygenated blood back to the heart to be oxygenated, while lymphatic vessels transport lymph towards the lymph nodes to be filtered and returned to the circulatory system.

What is the structure of lyphatic capillaries?

thin-walled, blind-ended vessels that are highly permeable, allowing the uptake of interstitial fluid, proteins, and other substances.

How do lymphatic transport compare to transport in the venous system?

Both are low-pressure systemst hat rely on muscle contractions and valves to facilitate fluid movement.

What mechanisms help propel lymph through the lymphatic vessels?

• Milking action of skeletal muscle 

•  Pressure changes in thorax during breathing 

• Valves to prevent backflow 

•  Pulsations of nearby arteries 

• Contractions of smooth muscle in walls of lymphatics

What are primary lymphoid organs and what happens there?

Red bone marrow and thymus; they are where T and B cells mature.

What are some secondary lymphoid organs?

Lymph nodes, spleen, MALT, and diffuse lymphoid tissue.

What occurs in secondary organs?

areas where mature lymphocytes first encounter their antigen and become activated

What changes occur in the spleen and lymph nodes as we age?

They may become less efficient in older adults and may have reduced immune response effectiveness.

What important events take place in the lymph nodes?

• The cleansing of the lymph as it flows back into the bloodstream  

• The immune system activation, which offers a place for lymphocytes to become activated and mount an attack against antigens 

What is the structure of the lymph nodes?

• Vary in shape and size but most are bean-shaped 

• Small, less than 2.5 cm (~1 inch) 

What is step 1 in fluid flow (circulation) in the lymph nodes?

The lymph enters the convex side of node through the afferent lymphatic vessels  

What is step 2 in fluid flow (circulation) in the lymph nodes?

Travels through large subcapsular sinuses and then into smaller sinuses found throughout the cortex and medulla. 

What is step 3 in fluid flow (circulation) in the lymph nodes?

The lymph enters the medullary sinuses 

What is step 4 in fluid flow (circulation) in the lymph nodes?

It exits on the concave side at the hilum using the efferent lymphatic vessels 

Where is the location of the lymph nodes?

distributed throughout the body, primarily located in areas such as the neck, armpits, and groin, serving as filters for lymph fluid where they are embedded deep in the connective tissue

What occurs in the spleen?

Lymphocyte proliferation, immune response, blood cleansing, and storage of blood platelets and monocytes.

What differentiates white pulp from red pulp in the spleen?

White pulp is involved in immune functions, while red pulp is responsible for destroying old blood cells.

What is MALT and its significance?

Mucosa-associated lymphoid tissue provides protection from pathogens at mucous membranes that are trying to get in

What are the largest collections of MALT found in the body?

Tonsils, Peyer's patches, and the appendix.

Where is the peyer’s patach located?

in the distal part of the small intestine, specifically in the ileum.

Where is the appendix located?

Found in the first part of the large intestine called the cecum.

What are the names of different tonsil locations?

Palatine, Lingual, Pharyngeal (adenoids), and tubal

What is the location of palatine tonsils?

Posterior end of the oral cavity ( largest tonsils and most often get infected)

What is the location of lingual tonsils?

lumpy collection of follicles at the base of the tongue 

What is the location of pharyngeal (adenoids) tonsils?

posterior wall of nasopharynx

What is the location of tubal tonsils?

surrounding openings of the auditory tubes into the pharynx

What is the name of an inflamed tonsil?

tonsillitis

What is the function of the thymus?

a lymphoid organ where T cell mature  

What is the location of the thymus?

bilobed lymphoid organ found in inferior neck 

How does the thymus differ from other lymphoid organs?

It does not have follicles or B cells and does not directly fight antigens; its stroma consists of epithelial cells.

What is the desired end result for each of the positive and negative selection processes? 

Positive can recognize self-MHC MHC protein, while negative can’t  

What changes occur in the thymus as a person ages?

The thymus stops growing during adolescence and gradually atrophies.

What is the purpose of tonsillar crypts?

They trap bacteria and foreign substances as part of the immune system.

What does the appendix do in the immune system?

It is involved in the immune response and its inflammation leads to appendicitis.