Lymph Anatomy & Physiology Flashcards
3 main functions of the lymphatic system
- lymphatic circulation
- immune system
- fat/fatty acid digestion
Lymph circulatory system
- one way drainage
- transport proteins that are too large to re-enter venous capillaries
- loose junctions btw endothelial cells encourages gapping
- tiny filaments that anchor lymph vessels to surrounding connective tissue
Immune support lymph organs (B and T lymphocytes and macrophages)
- lymph vessels and nodes
- thymus gland
- bone marrow
- spleen
- tonsils
- bowel/mucous membranes
- appendix
Major lymph node collection sites
- colon
- axilla
- neck
- inguinal region
- bronchial region
Lymph node functions
- antigen presentation
- immune cell recognition
- phagocytosis
Lymph node sequence of events
- antigen enters lymph node through lymph vessel
- triggers inflammation and causes lymphocytes & macrophages to multiply in the lymph node causing swelling
- phagocytosis begins
- inflammation & increased WBCs cause lymph fluid to thicken
Direction of flow in lymphatic circulation
- lymphatic capillaries
- lymph nodes
- lymph trunks
- lymph ducts
- internal jugular/subclavian veins (right lymphatic duct enter R subclavian vein and left thoracic duct enter L subclavian vein)
What areas does the right lymphatic duct drain in the body
- right UE
- right side of trunk
- right side of face
Describe lymph vessels
- located superficially in the skin, subcutaneous, and deep fascia
-parallel the venous system - thinner walls, more valves, & contain lymph nodes at designated points
3 layers of lymph vessels
- Intima: one layer of endothelial cells
- Media: smooth muscles
- Adventitia: collagen
What is lymph flow controlled by
- tissue pressure
- circulatory system is controlled by a central pump
What is lymph flow facilitated by
- intermittent skeletal muscle activity
- lymphangion vessel contractions
- an extensive system of one way valves
Lymphangions
- region btw valves
- smooth muscle stretch reflexes sensing when it fills with lymph fluid
- contracts 6-12 times at rest and increases 10 fold with aerobic activity
Other physiological pressures that influence lymph flow
- arterial pulsations
- postural changes
- respiratory pressure changes
- scar tissue
- body mass/skin folds
Transport capacity
- amount of lymph volume that can be transported in a given period of time
Contraction regulation
- sympathetic NS regulates contraction in the lymphangion
- pain and stress can decrease the activity of the lymph flow in the lymphangion
High output failure
- lymphatic load is too great to transport the fluid from the interstitium
- caused by anything that causes swelling (ex. an injury)
Low output failure
- lymphatic system has difficulty transporting a minimal amount of high protein fluid from the interstitium due to damage in the lymph vessels or lymph nodes
Combined insufficiency
- combination of a high output failure & a low output failure
- high output failure due to infection, trauma, or surgery
- low output failure due to previous injury to lymph vessels or modes (ex. radiation therapy)
Lymphedema
- low output failure
- consists of protein rich fluid & low grade inflammation with reactive fibrosis as a result of altered/damaged lymph transport capacity
What is the only diagnostic imaging to diagnose lymphedema
- lymphoscintigraphy
Congenital abnormality of development of the lymphatics
- hypoplasia: reduced # of lymph collectors & decreased diameter of lymph vessels
- hyperplasia: increased # of collectors
- aplasia: absence of lymph system components
- kinmoth syndrome: inguinal lymph node fibrosis
Milroy disease, lymphedema praecox, and lymphedema tarda
- Milroy: observed at birth due to gene mutation
- Praecox: developed before 35
- Tarda: developed after age 35
Prevalence for primary lymphedema
- females 2x more than males
- LE 3x more than UE
- Bilateral 2x more than unilateral