A&P Ch 21

Describe what lymph is and draw a flow chart that illustrates what structures the lymph travels through to return to the blood.

Lymph is interstitial fluid that passively enters lymphatic capillaries. Flowchart: lymphatic capillary lymphatic vessels lymph nodes lymphatic trunks lymphatic ducts venous blood.

Why is red bone marrow considered a primary lymphatic structure?

Red bone marrow is considered a primary lymphatic structure because it is the site of production of all formed elements in the blood, including all lymphocytes, whereas secondary lymphatic structures house lymphocytes following their formation. (lymph nodes, spleen: white pulp, tonsils, lymph nodules/MALT)

A child born without his thymus would not have mature

T-cells

Describe how the thymus's anatomy changes as we age.

The thymus continues to grow until puberty, when it reaches a maximum weight of 30 to 50 grams. Cells within the thymus begin to regress after it reaches this size. Thereafter, much of the thymic tissue is replaced by adipose connective tissue.

In an early Streptococcus infection of the throat, all of the following structures may swell expect the a) pharynegeal tonsil b) spleen c) cervical lymph node d) bronchomediastinal trunk

b) spleen

A young woman was in a card accident and had to have her spleen removed as a consequence of its rupture during the accident. She now has greater risk of

bacterial infection

Which statement is accurate about lymph nodes? a) lymph nodes do not become swollen and tender. b) lymph nodes filter blood c) lymph enters the lymph node through afferent lymphatic vessels d) lymphatic sinuses are located in the cortex of a lymph node only

c) lymph enters the lymph node through afferent lymphatic vessels

What body systems are supported by the lymphatic system?

cardiovascular and immune The lymphatic system returns excess fluid to the blood to maintain fluid balance and blood pressure (thus, supporting the cardiovascular system). It also houses lymphocytes and macrophages to defend against foreign substances (thus, supporting the immune system).

A tick has embedded itself in the scalp of a young boy. his mother is most likely to find which lymph nodes to be swollen?

cervical lymph node

Which type of lymph vessel consists solely of an endothelium and has one-way flaps that allow interstitial fluid to enter but not exit?

lymphatic capillaries Lymphatic capillaries are homologous with blood capillaries in that they consist of a simple endothelial layer, although they are typically larger in diameter. Unlike blood capillaries, they also possess overlapping endothelial cells that act as one-way flaps to allow interstitial fluid to enter the lymphatic system.

Aged erythrocytes are removed from circulation by the

spleen

The lymphatic trunk that drains lymph from the upper limb, breasts, and superficial thoracic wall is the

subclavian trunk

All of the following can result in lymphedema (the accumulation of interstitial fluid due to interference with lymphatic drainage) except a) surgical removal of a group of lymph nodes b) obstruction of lymph vessels that drain a lymph node, such as might occur with a tumor c) radiation therapy, which may cause scar formation of lymph vessels d) exercise that increases the flow of lymph in the lymph vessels

d) exercise that increases the flow of lymph in the lymph vessels

One of the postoperative complications from the removal of lymph nodes during a mastectomy would be

edema of the upper limbs

The spleen is a secondary lymphatic structure that is located

inferior to the diaphragm and adjacent to the stomach

What is the function of the thymus?

it is the site of T-cell maturation

Interstitial fluid that is absorbed into lymph vessels will be monitored by the _____ before the fluid is dumped into venous blood.

lymph nodes

Describe the specific locations of the tonsils.

A pharyngeal tonsil is found in the posterior wall of the nasopharynx, palatine tonsils are located in the posterolateral region of the oral cavity, and the lingual tonsils are located along the posterior one third of the tongue

How are the two types of T-lymphocytes arranged in the cortex and medulla?

Each lobule of the thymus is arranged into an outer cortex and inner medulla. The cortex of the thymus contains immature T-lymphocytes (pre T-lymphocytes) and the medulla contains mature T-lymphocytes.

Describe the basic anatomy of a lymph node, how lymph enters and leaves the node, and the functions of this organ.

Lymph nodes are small, round or oval encapsulated structures located along the pathways of lymph vessels where they serve as the main lymphatic organ. Numerous afferent lymphatic vessels will bring lymph into a lymph node. Lymph passes through the node sinuses located in the medulla of the lymph node and then exits through the one efferent lymphatic vessel. The function of the node is to expose lymph to macrophages and lymphocytes within the node. Macrophages will remove foreign particles from the lymphatic fluid. Lymphocytes will initiate an immune response upon exposure to the foreign particles.

What substances typically are absorbed from the interstitial space into lymphatic capillaries?

Lymphatic capillaries typically absorb water, dissolved solutes, and small amounts of protein, and sometimes foreign materials including cell debris, pathogens, and perturbs metastasized cancer cells.

Describe the location and function of diffuse lymphatic nodules and mucosa-associated lymphatic tissue (MALT)

Lymphatic nodules are small, oval clusters of lymphatic cells with some extracellular matrix that are not completely surrounded by a connective tissue capsule. They are found within every organ of the body and within the wall of the appendix. In some areas of the body, many lymphatic nodules will group together to form larger structures, such as MALT.

Which lymphatic structures filter lymph? Which filters blood?

Lymphocytes nodes filter lymph, and the spleen filters blood.

How does lymph flow through a lymph node, and how is it monitored by macrophages and lymphocytes?

Numerous afferent lymphatic vessels will deliver lymphatic fluid to a lymph node. The "collective diameter" of the numbers afferent vessels is greater than the diameter on the single efferent vessel, resulting in the generation of a higher fluid pressure to help force the lymph through the node. As the materials within the fluid percolate through the sinuses located within the medulla of the lymph node, they will be exposed to macrophages and lymphocytes. Macrophages will remove foreign particles from the lymphatic fluid. Lymphocytes may be stimulated to imitate an immune response upon exposure to the foreign particles.

Explain what distinguishes a primary lymphatic structure from a secondary lymphatic structure.

Primary lymphatic structures are involved in the formation and maturation of lymphocytes. They include: bone marrow and the thymus. Secondary lymphatic structures include the lymph nodes, spleen, tonsils, lymphatic nodules, and MALT. They are not involved in formation of lymphocytes but instead serve to house both lymphocytes and other immune cells following their formation.

How are primarily lymphatic structures and secondary lymphatic structures differentiated? What are examples of each?

Primary lymphatic structures, such as bone marrow and the thymus, are involved in the formation and maturation of lymphocytes and other immune cells following their formation, and they also provide the site where an immune response is initiated. The major secondary structures include the lymph nodes, spleen, tonsils, lymphatic nodules, and MALT.

How does fluid enter and become "trapped" in the lymphatic capillaries?

The hydrostatic pressure of interstitial fluid separates the endothelia cells that form the lymphatic capillaries, allowing the interstitial fluid to enter the lymphatic capillary lumen. Once inside the lymphatic capillary, the fluid exerts hydrostatic pressure on the endothelial cells, closing the gaps and trapping the fluid (now called lymph) in the lymphatic capillary.

What is the function of MALT in the mucosal linings of the gastrointestinal, respiratory, urinary, and reproductive tracts?

The lymphatic cells in the MALT help defend again foreign substances that come in contact with mucosal membranes.

Explain how the lymphatic system supports the functions of both the cardiovascular system and the immune system.

The lymphatic system aids the cardiovascular system by returning excess fluid to the blood to maintain fluid balance, blood volume, and blood pressure. It also provides support to the immune system by transporting and housing lymphocytes and other immune cells that help the immune system defend against foreign substances.

List the anatomic structures of the lymphatic system, including lymph vessels, primary lymphatic structures, and secondary lymphatic structures.

The lymphatic system is composed of 1) lymph vessels (lymphatic capillaries, lymphatic vessels, lymphatic trunks, and lymphatic ducts) 2) primary lymphatic structures (red bone marrow and the thymus) 3) secondary structures (lymph nodes, spleen, tonsils, lymphatic nodules, and MALT)

Which major body regions drain lump to the right lymphatic duct?

The right lymphatic duct receives lymph from 1) the right side of the head and neck 2) the right upper limb and 3) the right side of the thorax.

What are the general functions of the spleen?

The spleen filters the blood. Trabeculae from the connective tissue capsule around the spleen extend into it to partition the spleen into white pulp (clusters of T-cells, B-cells, and macrophages) and red pulp (houses erythrocytes, platelets, macrophages, and B-cells) that forms cords of cells with associated sinusoids. It serves several functions: 1) phagocytosis of bacteria and other foreign materials for body defense (red pulp and white pulp) 2) phagocytosis of old, defective erythrocytes and platelets from circulating blood (red pulp) and 3) creating a blood reservoir and storage site for both erythrocytes and platelets (red pulp)

Compare and contrast the red and white pulp of the spleen with respect to the anatomy and functions of each.

The spleen is surrounded by a connective tissue capsule from which trabeculae extend into the organ. It lacks a cortex and medulla, but the trabeculae subdivide the spleen into red pulp and white pulp. The red pulp is found within sinusoids. It contains erythrocytes, platelets, macrophages, and B-lymphocytes. These cells are housed in reticular connective tissue and form structures called splenic cords. The red pulp serves as a blood reservoir, including a storage site for both erythrocytes and platelets, and also removes old erythrocytes and platelets from circulation. The white pulp consists of spherical clusters of T-lymphocytes, B-lymphocytes, and macrophages which surround a central artery. Lymphatic cells within the white pulp monitor the blood for foreign materials, bacteria, and other potentially harmful substances.

What mechanisms are used to assist lymphatic movement through lymphatic vessels?

The system lacks a pump, and thus it relies on several mechanisms to move lymph through its vessels: 1) contraction of derby skeletal muscles in the limbs (skeletal muscle pump) and the respiratory pump in the torso 2) the pulsatile movement of blood in nearby arteries and 3) rhythmic contraction of smooth muscle in walls of larger lymph vessels (trunks and ducts).

Which body regions have their lymph drained to the thoracic duct.

The thoracic duct drains lymph from the left side of the head and neck, left upper limb, left thorax, all of the abdomen and both lower limbs.

What are the three main group of tonsils and their function?

The three main groups of tonsils are the pharyngeal, palatine, and lingual tonsils. Tonsils function to help protect against foreign substances that may be either inhaled or ingested.

Lymph is drained into the thoracic duct from which body regions? a) right lower limb b) right upper limb c) right side of the head d) right side of the thorax

a) right lower limb