Lymphatic Flashcards
What are the functions of the lymphatic system
◦ Transport and house lymphocytes and
other immune cells
◦ Return excess fluid in body tissues to
blood to maintain blood volume
What are the components of the lymphatic system
- Lymph vessels
- Lymph tissues/organs
- Lymph fluid
How Is lymph fluid created?
Fluid that leaves the capillaries and is not reabsorbed are moved to the lymph capillaries
What is lymph (fluid) made of?
◦ Water, dissolved solutes, and small amount of protein
◦ Sometimes cell debris, pathogens, or cancer cells
Characteristics of lymph capillaries?
interspersed around most blood capillaries. Slightly larger than blood capillaries. Walls are composed of overlapping endothelial cells.
What are flaps?
Functionally identical to valves, allow lymph fluid to enter but not exit.
What are anchoring filaments?
attach capillary to neighboring structures.
What is a lacteal?
lymphatic capillaries in GI tract
How is lymph moved in to the lymph capillaries
Hydrostatic pressure,
Pressure of lymph inside increases, forcing flaps to close
What is the path of lymph?
Capillaries, vessels, trunks, ducts
cars, vans, trucks, dump trucks.
ultimately moved back in to circulation
Lymph vessels are fed by…
Lymph capillaries
Characteristics of lymph vessels
- Located adjacent to arteries and veins
- Have all three vessel tunics (intima, media, externa)
- Have valves to prevent pooling and backflow
Lymph system has no pump so it uses…
◦ Skeletal muscles and respiratory pumps
◦ Pulsatile movement of blood in nearby arteries
◦ Rhythmic contraction of smooth muscle in larger lymph vessel walls
Jugular trunks
head and neck
Subclavian trunks
upper limbs, breasts, and superficial thoracic wall
Bronchomediastinal trunks
deep thoracic structures
Intestinal trunks
most abdominal structures
Lumbar trunks
lower limbs, abdominopelvic wall, and pelvic organs
Lymphatic Vessels, Trunks, and Ducts
Lymphatic ducts are fed by
lymphatic trunks
Right lymphatic duct
located by right clavicle
Drains upper right quadrant of body
Delivers lymph to junction of right subclavian and right internal jugular veins
Thoracic duct
largest lymphatic vessel
◦ Saclike cisterna chyli at its base
◦ Receives lipid-rich chyle from GI tract Lymphatic Vessels, Trunks, and Ducts
◦ Drains lymph from everything but upper right quadrant
◦ Delivers lymph to junction of left subclavian and left internal jugular veins
Primary lymphatic structures
◦ Involved in formation and maturation of lymphocytes
◦ Red bone marrow and thymus
Secondary lymphatic structures
◦ Sites of immune response initiation
◦ Do not form lymphocytes, but house them and other immune cells
◦ Include lymph nodes, spleen, tonsils, and lymphatic nodules, MALT
Thymus
T-lymphocyte maturation
Two lobes
Trabeculae divide lobes in to lobules
Lobules contain a cortex (outer region) – contains immature T-lymphocytes and a medulla (inner region) – contains mature T lymphocytes
Organization of the secondary lymph structures
Organized into lymphatic organs and aggregates of lymphatic nodules
◦ Organs have a complete capsule (spleen, lymph node)
Other lymphatic structures have an incomplete capsule or lack one (Tonsils, MALT, diffuse lymphatic nodules)
Lymph nodes
filter lymph, remove unwanted substances
Occur in clusters receiving lymph from body regions ◦
Components of the lymph node
Afferent vessels
Efferent vessels
hilum
Trabeculae
outer cortex
inner medulla
shape of lymph node
Small, oval, encapsulated structures
Lymph nodes are located
along deep and superficial pathways of lymph vessels
Cervical lymph nodes
lymph from head, neck
Axillary lymph nodes
lymph from breast, axilla, and upper limb
Inguinal lymph nodes
lymph from lower limb and pelvis
Afferent vessels
Bring lymph to node
Efferent vessels
drain lymph from node
Efferent vessels are located at the hilum
Lymph node cortex contains
lymphatic nodules
center of lymph nodule
germinal center
Germinal center
Houses developing B-lymphocytes and macrophages
◦ Surrounding mantle zone contains T-lymphocytes, macrophages, and dendritic cells
tiny open channels lined by macrophages where lymph flows
Cortical sinuses
Lymph node’s medulla contains
medullary cords
medullary cords
connective tissue fibers that support B-lymphocytes, T-lymphocytes, and macrophages
Medullary sinuses
are tiny open channels lined with macrophages
◦ Lymph from cortical sinuses flows here
How does lymph flow through the nodes?
Lymph enters from multiple afferent vessels, creating pressure to push it through the node. Lymph Is then monitored for presence of foreign material. Macrophages remove debris. Lymphocytes may intiate immune response.
Proliferating lymphocytes cause
swelling of the node
Lymph exits node through
one efferent vessel
Spleen
◦ In left upper abdominal quadrant
◦ Posterolateral aspect is convex and rounded
◦ Anteromedial border is concave
-spleenic artery supplies and splenic vein drains
Hilum of spleen
indentation where blood vessels and
nerves enter
White pulp
Clusters of T- and B-lymphocytes and
macrophages around central artery
Red pulp
◦ Contains erythrocytes, platelets,
macrophages, and B-lymphocytes
◦ Permeable capillaries
◦ Storage of 30% of the body’s
platelets
What does the spleen do?
Monitoring blood as it flows through the spleen
◦ The spleen filters and monitors blood (not lymph)
◦ White pulp monitors it for foreign materials and bacteria
◦ Phagocytizes bacteria and cell debris
◦ Macrophages in sinusoids of red pulp remove particles
◦ Phagocytizes bacteria, debris, defective erythrocytes and platelets
Path of flow of spleen
splenic artery > central artery (white pulp) > venules (red pulp) > splenic vein
Tonsils
◦ Secondary lymphatic structures
◦ Immune surveillance of inhaled and ingested substances
3 types
Tonsillar crypts
◦ Invaginations that trap materia
Pharyngeal tonsil
◦ In nasopharynx
◦ Called adenoids when enlarged
Palatine tonsils
In posterolateral oral cavity
Lingual tonsils
Along posterior one-third of tongue
What does MALT stand for
Mucosa-associated lymphatic tissue
what does malt do?
◦ Located in GI, respiratory, genital, and
urinary tracts
◦ Help defend against foreign substances
◦ Prominent in small intestines
