returns fluids that have leaked from the blood vascular system back to the blood
Lymphoid organs and tissue
provide the structural basis of the immune system
lymphatic vessels, or lymphatics
elaborate networks of drainage vessels that collect the excess protein-containing interstitial fluid and return it to the bloostream
once interstitial fluid enters the lymphatic vessels it is called lymph (lymph means clear water)
these capillaries weave between the tissue cells and blood capillaries in the loose connective tissues of the body
specialized lymphatic capillaries that transport absorbed fat from the small intestine to the bloodstream (lact=milk)
(chyle=juice)fatty lymph drains from the fingerlike villi of the intestinal mucosa
collecting lymphatic vessels
have the same three tunics as veins, but they have thinner walls and more ineternal valves, and they anastomose more.
largest collecting vessels unite to form these, they drain fairly large areas of the body
What are the major lymphatic trunks?
lumbar, bronchomediastinal, subclavian, jugular trunks, and the single intestinal trunk
Right lymphatic duct
drains lymph from the right upper limb and the right side of the head and thorax
(much larger than R Lymphatic duct) receives lymph from the rest of the body
that collects lymph from the two large lumbar trunks that drain the lower limbs and from the intestinal trunk that drains the digestive organs
main warriors of the immune system, arise in red bone marrow
What are the two types of Lymphocytes?
T cells and B cells that protect the body against antigens
daughter cells that secrete antibodies into the blood (or other body fluids)
these play a crucial role in body protection and the immune response by phagocytizing foreign substances and by helping to activate T cells.
capture antigens and bring them back to the lymph nodes
fibroblast-like cells that produce the reticular fiber stroma
which is the network that supports the other cell types in lymphoid organs and tissues
Reticular connective tissue
dominates all the lymphoid organs except the thymus. largely composed of a type of loos connective tissue
Diffuse lymphoid tissue
loose arrangement of lymphoid cells and some reticular fibers
Lymphoid follicles (lymphoid nodules)
solid spherical bodies consisting of tightly packed lymphoid cells and reticular fibers
proliferating (increase rapidly) B cells predominate, they are lighter-staining
which cluster along the lymphatic vessels of the body. embedded in connective tissue, but there are hundreds of these small organs
Lymph nodes in filteration:
as lymph is transported back to the bloodstream the lymph node act as lymph filters.
lymph nodes in immune system activation
lymph nodes and other lymphoid organs are strategically located sites where lymphocytes encounter antigens and are activated to mount an attack against them.
connective tissue strands that extend inward to divide the node into a number of compartments
What are the two histologically distinct regions of the lymph node?
The cortex and medulla
extend from the cortex in the lymph node and contain B cells, T cells, and plasma cells (macrophages reside on these fibers)
large lymph capillaries spanned by crisscrossing reticular fibers
Afferent Lymphatic vessels
Lymph enters the convex side of a lymph node through a number od afferent lymphatic vessels
number of smaller sinuses that cut throug hthe cortex and enter the medulla
the indented region on the concave side
soft, blood-rich spleen is about the size of a fist and is the largest lymphoid organ
What are the 2 components of the spleen?
White pulp, and Red pulp
White pulp in the spleen
where immune functions take place, so it is composed mostly of lymphocytes suspended on reticular fibers
Red Pulp of the spleen
where worn-out red blood cells and bloodborne pathogens are destroyed, contains huge numbers of erythrocytes and the macrophages that engulf them
Mucosa-associated lymphoid tissues (MALT)
prtoects the digestive, reproductive, and respitory systems from foreign matter. \ distributed lymphoid tissues strategically located in mucous membranes throuhout the body. - peyer's patches, tonsils, and the appendix
4 locations of tonsils:
palatine tonsils (these are what get removed), lingual tonsils (can't be removed), pharyngeal tonsils, tubal tonsils (can't remove these)
large clusters of lymphoid tissue, structurally similar to the tonsils - found in small intestine
tubular offshoot of the efirst part of the large intestine and contains a high concentration of lymphoid follicles
buds from developing veins
Thymosin makes what:
T cells and B cells
What are the two basic functions of the Lymph nodes?
1. filteration - microphages destroy microorganisms, and debris
2. immune system activation - monitor for antigens and mount an attack against them
What are the two main functions of the Lymphatic System?
1. returns intersitial fluid&plasma back to blood
2. filters lymph
What is the order that the lymph flows toward the heart?
1. Lymphatic Capillaries
2. Lymphatic Collecting vessels
3. Lymph nodes- filters
4. Trunks and ducts
The minivalves of the Lymphatic capillaries function as one-way gates that:
-allow interestitial fluid to enter lymph capillaries
-do NOT allow lymph to escape from the capillary
What is the principal lymphoid organ of the body?
Where do the Lymph node aggregations occur in the body?
inguinal, axillary, and cervical regions
The superficial cortex of the Lymph Node contains:
follicles w/ germinal centers (heavy w/ dividing B cells: prdocue plasma cells)
The deep cortex of the Lymph Node houses:
T-cells in transit
Lymphatic trunks are formed by what:
the union of the largest collecting ducts
Where do fetal erythrocyte produce?
structures found in the medulla of the thymus (areas where hormone is produced)
What is the first line of defense?