Lecture: Anatomy 8: Lymphatic System Flashcards
What is the lymphatic system?
Morphologic counterpart of the immune system that consists of groups of cells, tissues, and organs that monitor body surfaces and internal fluid compartments.
What are the functions of the lymphatic system?
- Fluid recovery
- Immunity; removal of debris from cellular decomposition and infection.
- Lipid absorption; lacteals absorb dietary lipids.
What are the components of the lymphatic system?
Lymph
Lymphatic vessels
Lymphoid organs
Lymphocytes
What is lymph?
Tissue fluid (interstitial fluid) which contains WBCs an d protein that enters the lymphatic vessels.
How much lymph is produced each day?
Normal lymphatic flow is 2L to 3L per day.
How is lymph made?
Roughly 3L of fluid fails to be reabsorbed by the blood capillaries and enters the extracellular spaces along with plasma proteins and materials from tissue cells.
How is lymph flow maintained in a singular direction?
Valves prevent backflow of lymph
What are lymphatic plexuses?
Networks oflymphatic capillaries in the extracellular spaces. Composed of highly attenuated endothelium with valve like flaps and no basement membrane.
Examples of fat-soluble vitamins?
A, D, E and K
What are lacteals?
Special types of lymphatic capillaries called lacteals which pick up not only interstitial fluid, but also dietary lipids and lipid-soluble vitamins.
Describe the composition of lymph in the lacteals
Lymph has a milky colour due to the lipid and is also called chyle.
What is the difference between afferent and efferent lymphatic vessels?
Afferent lymph vessels carry lymph to the lymph node whereas efferent lymph vessels take lymph away from the lymph nodes.
What are the 3 layers within lymphatic vessels?
- Endothelium (1 cell thick)
- Tunica media (smooth muscle)
- Tunica adventitia (connective tissue)
No basement membrane to aid movement of fluid into lymphatic vessels.
What is the difference between superficial and deep lymphatic vessels?
Superficial lymphatic vessels converge towards and follows venous drainage and eventually drain into deep lymphatic vessels. Deep lymphatic vessels accompany arteries and receive drainage of internal organs.
Hydrostatic pressure?
Drives fluid from capillaries into interstitial space
Osmotic pressure?
Drives fluid interstitial space into capillaries
How do lymph flow through the body?
- Interstitial space (interstitial fluid)
- Lymphatic plexuses
- Lymphatic vessels
- Lymph nodes
- Lymphatic vessels
- Lymphatic trunks
- Lymphatic ducts
- Venous circulation
- Blood capillaries (blood)
What mechanisms are used to push lymph around the body towards the heart and into the venous circulation?
- Filtration pressure in tissue spaces.
- Contraction of neighbouring skeletal muscles.
- Respiratory movements.
- Contraction of lymphatic vessel walls.
How do lymphatic vessels anchor into surrounding cells?
Anchoring filaments
Where are lacteals commonly found?
Small intestine
What are lymphatic trunks?
Lymphatic trunks (collecting vessles)are large collecting vessels that receive lymph from multiple lymphatic vessels.
What vessels join up to lymphatic trunks?
Right lymphatic duct or the thoracic duct unite at the lymphatic trunks.
What is the role of the right lymphatic duct?
Drains lymph from the body’s right upper quadrant.
What is the role of the thoracic duct?
Largest lymphatic channel that drains lymph from the remainder of the body.
What is the cisterna chyli?
A dilated collecting sac formed by the merging of the lymphatic trunks draining the lower half of the body.
What are the 5 main lymphatic trunks?
- Jugular trunk
- Subclavian trunk
- Bronchoediastinal trunk
- Collecting trunk
- ???
Where does the right lymphatic duct drain into?
Right lymphatic duct drains into right venous angle composed of right subclavian vein and right internal jugular vein
Where does the left (thoracic) duct drain into?
Left lymphatic duct drains into left venous angle composed of left internal jugular vein and left subclavian vein.
What are the primary lymphatic organs?
Bone marrow
Thymus
How do T and B cells move from primary lymphatic organs to secondary lymphatic organs?
Lymphocytes enter the blood or lymphatic vessels from primary lymphatic organs to colonise secondary lymphatic organs and tissues, where they undergo the final stages of antigen-dependent activation.
What are the secondary lymphatic organs?
Lymph nodes
Aggregation of lymphatic nodules
Spleen
What is red bone marrow?
Red bone marrowconsists of blood cells in different stages of development and a network of reticular cells and fibres that serve as a supporting framework for the developing blood cells and vessels.
What is yellow bone marrow?
Produces fat cells (adipocytes). In response to appropriate stimuli, such as extreme blood loss, yellow marrow can revert to red marrow.
Where is red bone marrow found?
Children – medullary cavity
Adults – spaces of spongy bone
What happens to the thymus with age?
Atrophies; replaced by fat cells.
What is the main function of the thymus?
Maturation of T cells in the inner medulla.
What are the functions of lymph nodes?
Lymph nodes filter lymph along the pathway of lymphatic vessels and initiate adaptive immune responses to antigens.
What are the gross anatomy components of lymph nodes?
Capsule (composed of dense CT) which invaginates and forms trabeculae.
Superficial cortex contains B cells & macrophages, whereas deep cortex (paracortex) contains T cells.
What are primary lymph nodes?
First node or group within chain
What are terminal lymph nodes?
Last node or group within chain
Where are deep lymph nodes found?
Lymph nodes are closely located to vasculature and viscera. Node nomenclature is often taken from neighbouring structures.
What are the 2 forms of lymphatic nodules?
- Diffuse lymphatic tissue
2. Lymphatic nodules
What are the 2 forms of lymphatic nodules?
- Diffuse lymphatic tissue
2. Lymphatic nodules (eg. Payers Patch)
What are the 3 types of lymphocytes?
Natural killer cells
T lymphocytes
B lymphocytes
How does lymph drain through lymph nodes?
Afferent lymphatic vessel Su Trabecular sinus Medullary sinus Efferent lymphatic vessel
