Lymphatic System Learning Objectives Flashcards
Describe lymph and its contents.
Lymph:
- Transports and houses lymphocytes and other immune cells that help the immune system defend agaisnt pathogens.
- Aids in the cardiovascular system by returning excess fluid to venous blood
Contents:
- Composed of water, dissolved solutes, small proteins, and foreign materials.
- 15% of interstitial fluid hets absorbed into the lymphatic system
Discuss the location and anatomic structure of lymphatic capillaries.
Location:
- Interspersed around most BLOOD capillaries
- ABSENT in avascular tissues, red marrow, spleen, and CNS (brain and spinal cord)
Anatomic Structure:
- Small, close-ended vessels that absorb interstitial fluid
- Walls are made up of overlapping endothelial cells
- Use anchoring filaments
Explain the mechanisms that move lymph through lymphatic
vessels, trunks, and ducts.
Movement of Lymph in Capillaries
- Increased in hydrostatic pressure within interstitial fluid (IF) pushes lymph into the capillaries
Movement of Lymph in Vessels
- Skeletal pump
- Respiratory pump
- Rhythmic contraction of smooth muscle in larger lymph vessels.
Movement of Lymph in Trunks
- Jugular Trunk: drain the head and neck
- Subclavian Trunk: drain from upper limbs, breast and thoracic wall
- Bronchomediastinal Trunk: drain the thoracic wall
- Intestinal Trunk: drain from abdominal structures
- Lumbar Trunk: drain the lower limbs, abdominopelvic walls and pelvic organs
Movement of Lymph in Ducts
- Right Lymphatic Duct: drains lymph from the upper right quadrant
- Thoracic duct: drains lymph from the rest of the body
Describe the flow of lymph from lymphatic capillaries through the
various types of lymph vessels until it is returned to the cardiovascular system.
Lymphatic capillaries
lymphatic vessels
lymphatic trunks
lymphatic ducts
R/L subclavian vein
Name the two categories of lymphoid structures and identify components of the body that belong to each category.
Primary Lymphatic Structures:
- formation and maturation of lymphocytes
- Red bone marrow & Thymus
Secondary Lymphatic Structures:
- House lymphocytes and other immune cells
- Lymph nodes, spleen, tonsils, lymphatic nodules, MALT (mucosa-associated lymphoid tissue)
Describe the location and general function of red bone marrow.
Location:
- within trabeculae of spongy bone
- flat bones of the skull, ribs, sternum, vertebrae, ossa coax, heads of humerus, and femur
General Function:
- Site of hematopoiesis
- T and B lymphocyte creation site
- B cells are matured here
Identify the unique step required by T-lymphocytes in their maturation.
T-cells migrate to the thymus for maturation
Describe the structure and function of the thymus.
Structure of Thymus:
- Bilobed organ located above the heart
- Two thymic lobes, surrounded by connective tissue capsule
- Trabeculae subdivides lobes into lobules
- Cortex contains immature T-lymphocytes
- Medulla contains mature T-lymphocytes
Function:
- T-lymphocyte maturation
- Thymulin participates in T cell maturation
Describe the structure of and function of lymph nodes.
Structure of Lymph Nodes:
- Cervical Lymph Nodes
- Axillary Lymph Nodes
- Inguinal Lymph Nodes
- Afferent lymphatic vessels: Brings lymph into the lymph node
- Efferent lymphatic vessels: Drains lymph
- Hilum: involute portion of cortex and medulla
Function of Lymph Nodes:
- Filters lymph and remove unwanted substances
- Oval, encapsulated structures
Describe the location, structure, and function of the spleen.
Location
- left upper abdominal quadrant
- lateral to kidney
Structure
- Largest lymphoid organs
- Surrounded by connective tissue capsule
- White pulp: White blood cell location. Monitors blood for foreign materials and bacteria. associated with arterial supply of the spleen.
- Red pulp: storage of erythrocytes and can destroy them. Venous drain occurs here—Platelet reservoir.
Function:
- Spleen only filters Blood
Identify the main groups of tonsils and their location and function.
Location
- Pharyngeal tonsil (aka adenoids)– pharynx
- Palatine tonsils – oral cavity
- Lingual tonsil (tongue)– along the back of the tongue
Function
- protect against foreign substances that may get inhaled or ingested
Describe the composition of individual lymphatic nodules.
- Clusters of lymphoid cells with some extracellular matrix
- Not surrounded by connective tissue capsule
- Found in every body organ
- Help defend against infection
Compare the locations of MALT and Peyer Patches.
MALT
- type of lymphoid nodule
- located in the gastrointestinal, respiratory, genital, and urinary tracts
Peyer Patches
- large collections of lymphoid nodules within the wall of the GI tract (small intestine)
