Lecture 21 Flashcards
Three primary functions of lymphatic system
- Drains excess interstitial fluid
- Transports dietary lipids
- Carries out immune response
Drains excess interstitial fluid
Drains ISF from tissue space and returns it to blood
Once ISF is in lymphatic it becomes lymph
Transports dietary lipids
Transport lipids and lipid-soluble vit (ADEK) absorbed by gi tract
Carries out immune response
Production, maintenance and distribution of lymphocytes (WBC, B&T cells)
Lymphocytes are WBC part of immune system
Lymphatic system is a drainage system that
Removes excess fluid from body tissues and returns it to bloodstream
Usually, blood plasma moves out of capillaries at the arterial end of capillary beds while
Tissue fluid containing wastes reabsorbs back in the venous end
How much fluid is left in the tissues in stead of being drawn back to the bloostream
15% (would cause swelling if accumulated
Lymphatic vessels begin as
Lymphatic capillaries (located in spaces bet cells, closed at one end)
Why can lymphatic capillaries absorb proteins and lipids (large) when blood cannot
Bc have a greater permeability
Lymphatic capillaries characteristics
- Slightly larger in diameter than blood capillaries
- Made of overlapping squamous epithelial cells that function as a one-way valve
- This one way valve structure permits ISF flow into them but not out
How and when does interstitial fluid enter lymphatic capillary
When pressure is greater in fluid than lymph, cells separate slightly like opening of one way door
When P is greater inside lymphatic capillary than ISF,
Cells adhere more closely and close gaps so lymph cannot escape
Bc gaps in lymphatic capillaries are big, they allow bacteria, WBC and others to enter, so
- Lymphatic syst is useful for large particles to reach bloodstream
- Used for dietary fat absorption in intestines
Lymphatic capillaries unite to firm lymphatic vessels, and along those there are
Lymph nodes (contains B&T cells)
Lymph nodes act to
Filter foreign particles from blood, playing an important role in immune response to infection
Majority of lymph nodes located within
Abdomen
B & T cells exposed to fluid as it passes through nodes so
Can mount immune response if detect pathogen
What in the nodes filter foreign particles out of fluid, engulfing pathogens to destroy them?
Macrophages
Sequence of fluid flow is
- Blood capillaries
- Interstitial fluid
- Lymphatic capillaries
- Lymphatic vessels
- Lymph nodes
- Lymphatic duct
- Junction and into veins (blood)
Interconnection between lymphatic and cardio
Lymph goes through vessels and nodes and then enters drainage points into veins just above heart
Primary lymphatic organs
Red bone marrow
Thymus
Stem cells in red bone marrow give rise to
Mature, immunocompetent B cells and pre-T cells
Where do pre T cells go to become immunocompetent
Thymus
Secondary lymphatic organs and tissues (where most immune response occur)
Lymph nodes, spleen, lymphatic nodules (include tonsils)
Tonsils are strategically positioned to
Participate in immune response against inhaled or ingested foreign substances
What is the largest single mass of lymphatic tissue in the body
Spleen
B T cells in spleen function
Immune functions like in nodes
Spleen macrophages function
Destroy blood borne pathogens by phagocytosis
Risk for patients without a spleen
Risk for sepsis (blood infection) due to loss of filtering and phagocytic functions of the spleen
How to reduce risk of sepsis
Pts who have undergone splenectomy take preventive antibiotics before any invasive procedures
