The Lymphatic System 2
Terms
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- Lymph
-
Fluid inside lymphatic vessels
derived from tissue fluid - Lymphatic vessels (lymphatics)
- Gen. term referring to "all" lymphatic vessels
- Lymphatic tissue (lymphoid)
- Esp. of reticular conn. tissue and lymphocytes
- Stroma
-
anatomical framework of lymphatic tissue
Reticular Fibers
Reticular cells
Macrophages - Reticular fibers
-
scattered
spread out
Part of the stroma of Lymphatic tissue - Macrophages
- destroys some foreign substances by phagocytosis
- Diffuse lymphatic tissue
-
not enclosed by a capsule
In lamina propria of mucous membranes
In most organs of body - Lymphatic Nodules
-
egg-shaped masses not enclosed by a capsule
Masses of lymphatic tissue
Outer cortex of lymphocytes
Some solitary; in mucous membranes
Some in masses or aggregates -
Lymphatic Nodules
EXAMPLE -
Tonsils
Peyer's patches in ileum
Appendix - Red Bone Marrow
-
meshes of the reticular network that contain the developmental stages of red blood cells, white blood cells, and megakaryocytes.
RBC and WBC are produced in spongy bone in long bones. - Lymphatic organs (major ones)
-
Lymph nodes
Tonsils
Spleen
Thymus - Lymphatic System (FUNCTIONS)
-
Returns tissue (interstitial or intercellular) fluid back to blood. Proteins esp. important.
Transports fats from G.I. tract to blood
Lymphocytes protect against bacteria, foreign substances through:
Lymphocyte T cells
Lymphocyte B cells - Lymphocyte T cells
- Destroy invaders directly or indirectly by producing substances
- Lymphocyte B cells
- Differentiate into "plasma cells" - these produce antibodies (fights antigens)
- Lymphatic vessels
-
From lymph capillaries
inner walls vs. veins but more valves esp. associated with visceral organs - Lymph capillaries
-
Blind tubules
isolated or in plexuses
larger and more B permeable vs. capillaries - Anchoring filaments
-
Attach to epithelial cells
extend into surrounding tissue spaces
edema pulls on filaments thus opening spaces btwn. cells - Lymphatic trunks
-
R and L lumbar
Intestinal (single)
R and L bronchomediastinal
R and L subclavian
R and L jugular - Lymphatic ducts
-
Thoracic duct (L. lymphatic)
R. lymphatic duct - Thoracic duct (L. lymphatic)
-
Ap. 18"
drain lft. side of body and all body above the ribs
Cisterna chili
Junction of L. int. jugular and L subclavian vein - Cisterna chili
-
Dilation oof and bigining of thoracic duct
origin of thoracic duct - Lymph nodes
-
Ap. 1" oval
bean shaped
about 600 - R. lymphatic duct
-
Ap. 1/2" long
drain upper rt. side of body
Junction of the R. int. jugular and R subclavian vein - Hilus (hilium)
-
Indentation
for lymphatic vessels (efferent), blood vessels, nerves, etc. - Capsule
-
Dense irr. conn. tissue
Trabeculae - Trabeculae
- extension of capsule penetrate inward and divide lobes into lobules
- Stroma of lymph node
-
Capsule
Trabeculae
Reticular fibers and cells - Parenchyma
-
White pulp
Red pulp - Cortex
-
outer portion of lobule
Lymphocytes - Medulla
-
inner
Reticular epithelial cells
Some lymphocytes
Thymic corpuscles - Germinal Centers
-
Lightly stained
center of nodules
produce lymphocytes - Medullary cords
-
Strands of lymphocytes
fixed macrophages and lymphocytes - Afferent lymphatic vessels
- Bring lymph toward node only
- Efferent lymphatic vessels
-
Located at hilus
conduct lymph away from node only - Lymph node Function
-
Filters lymph and removes foreign substances
Produces lymphocytes (w.b.c's) - Cervical
- neck
- Axillary
- armpit
- Inguinal
- groin area
- Summary of Lymph flow
- Plasma (from blood) - interstitial spaces (now called tissue fluid) - to lymph capillaries (now called lymph) - to lymph nodes via afferent lymphatic vessels - to cortical sinuses of node - medullary sinuses of node - lymph exits node via efferent lymphatic vessels at hilus - lymphatic trunks - lymphatic ducts (2)(R and L lymphatic thoracic ducts) - back to blood at junction of R and L internal jugular and subclavian veins.
- Valved lymphatic vessels
- ensure the one way movement of lymph.
- Respiratory movement
- lymph moves from high pressure regions in body to low pressure regions in thoracic cavity.
- Tonsils
-
Aggregated lymph nodules
Encircle oral cavity and pharynx
Manufacture lymphocytes and antibodies -
Tonsils
(examples) -
Pharyngeal (adenoids)
Palatine
Lingual - Spleen
-
largest single mass of lymphatic tissue in body (12cm)
left hypochondriac region of body
btwn stomach and diaphram - Gen. Shape of spleen
- neighboring organs make indentations in visceral surface of spleen.
- Stroma of spleen
-
Capsule
Trabeculae
Reticular fibers and cells - White pulp
-
blood passing through white pulp worked on by B and T cells and macrophages
consists of:
Central arteries
Splenic nodules (malphighian corpuscles) - Central arteries
- Are the numerous branches of the splenic artery
- Splenic nodules (malphighian corpuscles)
-
Surround central arteries
esp. of lymphocytes and macrophages - Red pulp
-
Blood passing through here cleansed of worn-out blood cells and platelets
stores platelets
produces blood cells (hemapoeisis) during fetal life
Consists of:
Venous sinuses
Splenic cords - Venous sinuses
-
blood sinuses
blood moves very slowly - Splenic cords
- consists of r.b.c.'s, macrophages, lymphocytes, plasma cells and granulocytes
- Hilus
-
Splenic artery and vein
Efferent lymphatic vessels - Function of spleen
-
Doesn't filter lymph
Produces B cells - develop into plasma cells - produce antibodies
Phagocytize bacteria, old R.B.C.'s and thrombocytes
Store and release blood
Produce R.B.C.'s in fetus - Accessory spleens
- can grow more if needed
- Thymus
- a bilobed organ located in the mediastinium btwn. sternum and aorta.
-
Thymus
(structure) -
Usually bilateral (thymic lobes)
Capsule
Trabeculae
Lobules
Cortex
Lymphocytes
Medulla
Reticular epithelial cells
Thymic corpuscles -
Thymus
(function) - Immunity
- Immunity
- Reticular epithelial cells produce hormones that help synthesize and distribute T cells to other lymphatic organs - it is therefore also considered to be an endocrine organ
- Lobules
-
divided into inner and outer portion
A section or subdivision of a lobe. - Lymphocytes of cortex of lobules
-
tightly packed
also present are reticular epithelial cells and macrophages - Reticular epithelial cells
- Produce thymic hormones
- Thymic Corpuscles
-
Concentric layers of flattened ret. epi. cells
filled with keratin granules and keratin