Lecture 23 - Lymphatic System Flashcards
Desc. lymphatic flow
L. capillaries –> vessels –> trunks –> ducts (right l.duct or left thoracic duct)—> vein (jugular vein/subclavian vein)
*No lymph in CNS!!
What assists lymph flow?
- Skeletal muscle contraction
- Pressure changes during breathing
- Contraction of surrounding arteries propel lymph
- Large lymphatic vessels (ducts and trunks) have thin layer of smooth muscle cells (abdomen n thorax)
Compare lymphatic capillary to normal vein
- Similarities: Both low pressure system and have valves
- Differences: L.capillary no cells present (unless during infection), uses lymphangion (compression by local veins and arteries) to propel lymph
Which are the 3 most important lymph nodes clinically?
- Neck (cervical)
- Groin (inguinal)
- Armpit (axillae)
(palpate lymph nodes to check for infection. If only one side lymph nodes swollen, infection only on one side)
Desc the structure of lymph nodes. What is a lymph node. (jus know)
- Lymph node is a collection of lymphoid follicles (contain immune cells) that have cortex (outer portion) and medulla (inner) with all sides surrounded by cortex except for hilum
- Has one efferent lymphatic vessel leaves via hilum; and multiple afferent
- Pale region is germinal centre
- Capsule made of reticulin (collagen III)
Function of lymph node
- Filters lymph: traps antigen and presents to T cells
- Contain macrophages, B cells and T cells that produce immune response
- Dendritic (antigen-antibody complex) cells enter with pathogens through lymph and leave through efferent
What causes lymphadenopathy? (enlarged lymph nodes)
- When lymph nodes fight infection, germinal centre production of lymphocytes ⬆️–> swell (might be painful)
- Cancers can metastasise to lymph nodes
- Lymphoma (malignant lymphoid tissue)
What are some examples of the primary and secondary lymphatic organs?
- Primary: thymus and bone marrow
- Secondary: spleen, tonsils, appendix, Payer’s patches (small intestine)
Function of thymus? Structure and linkage to myasthenia gravis?
- Maturation of T cells (thymic cell education)
- Atrophies during puberty (replaced w fat)
- Septa and capsule made of reticulin
- In M.G, thymus undergo changes leads to Myasthenia Crisis –> difficulty swallowing
Function of spleen is
Immune function: - Antigen presentation - Proliferation and activation of B and T lymphocytes (production of antibodies) - Removal of antigen (by macrophages)
Haemopoietic function:
- Removal of old/damaged RBC
- Retrieval of iron from Hb
- RBC storage
What are effects of splenectomy and splenomegaly why occur?
- Spleen is highly vascular structure –> rupture –> death by exsanguination (internal bleeding) –> prevent by removing spleen
- Splenectomy: liver and RBC will take over removal of dmg RBC; risk of infection by encapsulated bac and malaria ⬆️
- Splenomegaly: due to glandular fever/malaria
Function of tonsils and location?
- Location: oropharynx (mouth) and nasopharynx (nose)
- Affected most in childhood, fully formed n func at birth
- Function: prevent ingress of pathogens thru nasal and oral route; crypts increase SA
- Form Waldeyer’s ring
Mechanism of tonsils
- Numerous M cells on surface
- Present antigen to underlying immune cells
- Swelling due to B and T cell proliferaton
(Green)
Location, structure and function of vermiform appendix
- Location: inferior and attached to colon
- Structure: has crypts and M cells on surface
- Function: prevent pathogen ingress from ileum, crypts increase SA
Where and what are Payer’s patches and function?
- Inferior and attached to ileum
- Many M cells
- Prevent pathogen ingress through digestion
