88 terms

chapter 20 The Lymphatic System and Lymphoid Organs and Tissues

Protein-containing fluid within
lymphatic vessels.
Stores blood platelets
Part of MALT.
Peyer's patches
Receives lymph from most of the
Thoracic duct
Small organs intimately associated
with lymphatic vessels
Lymph nodes
Largest lymphatic organ
Isolated clusters of lymph follicles
found in the wall of the small intestines
Peyer's patches
Peyer's patches are clusters of lymphoid tissue found primarily in the large intestine.
The lymphatics function to absorb the excess protein-containing interstitial fluid and return it to the
Lymph always flows away from the heart.
Lymphatic capillaries are permeable to proteins
Digested fats are absorbed from the intestine by the lymph capillaries
Chyle is delivered to the blood via the lymphatic system
All lymphoid organs develop from mesoderm
About 3 liters of fluid are lost to the tissue spaces every 24 hours and are returned to the bloodstream as
Because lymph vessels are very low-pressure conduits, movements of adjacent tissues are important in
propelling lymph through the lymphatics
Lymphoid tissue is mainly reticular connective tissue
Lymphocytes reside temporarily in lymphoid tissue, then move to other parts of the body
All the lymphoid organs are well developed before birth
An infected lymph gland is called a bubo
The largest lymphatic vessels are called lacteals
The cisterna chyli collects lymph from the lumbar trunks draining the upper limbs and from the intestinal trunk
draining the digestive organs
If even a small part of the spleen is left in a ten-year-old child, it will most likely regenerate itself.
The thymus lacks T cells
Small organs associated with lymphatic vessels are termed ________.
lymph nodes
Which of the following would not be classified as a lymphatic structure?
The distal portion of the small intestine contains clumps of lymph follicles called ________.
Peyer's patches
Both lymph and venous blood flow are heavily dependent on ________.
skeletal muscle contractions and differences in thoracic pressures due to respiratory movement
The thymus is most active during ________.
Which lymphatic structure drains lymph from the right upper limb and the right side of the head and thorax?
right lymphatic duct
What effect does age have on the size of the thymus?
The thymus initially increases in size and then decreases in size from adolescence through old age
The lymphatic capillaries are ________.
more permeable than blood capillaries
Antibodies that act against a particular foreign substance are released by ________.
plasma cells
Lymph leaves a lymph node via ________.
E efferent lymphatic vessels
By secreting hormones, the thymus causes what cells to become immunocompetent
Functions of the spleen include all of those below except ________.
crypts that trap bacteria
When the lymphatics are blocked due to tumors, the result is ________.
severe localized edema distal to the blockage
Select the correct statement about lymph transport
Lymph transport depends on the movement of adjacent tissues, such as skeletal muscles
Select the correct statement about lymphocytes
B cells produce plasma cells, which secrete antibodies into the blood.
Select the correct statement about lymphoid tissue
Lymphoid tissue is predominantly reticular connective tissue
A ring of lymphoid tissue that appears as a swelling of the mucosa in the oral cavity is called a(n) ________.
Which is not a mucosa-associated lymphatic tissue?
Peyer's patches are found in the ________.
ileum of the small intestine
Lymph collecting or pooling from the lower extremities would first pool in the ________ before moving on up.
cisterna chyli
What is a bubo?
an infected lymph node
What is the function of a Hassall's corpuscle
It has no known significant function.
Particularly large clusters of lymph nodes occur in all of the following locations except the ________.
lower extremities
Digestive tract-associated lymphatic tissue includes all of the following except ________.
islets of Langerhans
Functions of the lymphatic system include ________.
transport of excess tissue fluid to the blood vascular system
The tonsils located at the base of the tongue are the ________.
lingual tonsils
Which of the following is not a normal component of lymph
red blood cells
A sentinel node is ________.
the first node to receive lymph from an area suspected to be cancerous
The ________ are the simplest lymphoid organs and are found at the entrance to the pharynx
The appendix, tonsils, and Peyer's patches are collectively called ________.
Highly specialized lymph capillaries called ________ are present in the villi of the intestinal mucosa
The thoracic duct of the lymphatic system empties into the ________.
left subclavian vein
Lymph nodes have more ________ lymphatic vessels than ________ lymphatic vessels
afferent; efferent
Of the organs in the lymphatic system, only the ________ becomes less important as you get older
Tonsils have blind-ended structures called ________.
Hassall's corpuscles are always found in the lighter-colored ________ regions of the thymus
The ________ pulp of the spleen forms cuffs around the central arteries
Lymphatic ________ are formed from the union of the largest collecting vessels.
Describe the structural and functional relationship of the vessels of the blood vascular system and the
lymphatic system
Vessels of the blood vascular system are relatively high-pressure conduits compared to vessels of the
lymphatic system. The same mechanisms that promote venous return in blood vessels act within
lymphatic vessels. Because lymphatics are usually packaged together in connective tissue sheaths
with blood vessels, the pulsating expansions of the nearby arteries also promote lymph flow.
Describe the mechanisms by which lymphatic fluid is moved through the lymphatics.
Lymphatic fluid is moved through the lymphatics by the milking action of active skeletal muscles,
pressure changes within the thorax during breathing, valves to prevent backflow, and pulsation of
adjacent arteries
What is the consequence of obstruction of the lymphatics
Obstruction of the lymphatics results in edema distal to the obstruction
Where are the lymph node aggregations most dense?
Lymph node aggregations are most dense near the body surface in the inguinal, axillary, and cervical
regions of the body
What is the special role of the thymus gland?
By secreting hormones, the thymus gland causes T lymphocytes to become immunocompetent
Name the tonsils and state their body locations
Palatine tonsils are located on either side at the posterior end of the oral cavity. The lingual tonsils lie
at the base of the tongue. The pharyngeal tonsils are in the posterior wall of the nasopharynx.
List the functions of the spleen.
The spleen's main functions are to remove aged or defective blood cells and platelets from the blood
and to store or release some of the breakdown products of RBCs to the blood for processing by the
liver. Other functions include acting as a blood filter and reservoir, serving as a site for erythrocyte
production in developing embryos, storing blood platelets, and providing a site for lymphocyte
proliferation and immune surveillance and response
Characterize lymph transport in terms of rate, volume, and ability to change
Lymph transport is sporadic and much slower than that occurring in veins. About 3 liters of lymph
enters the bloodstream in a 24-hour period. An increase in physical activity will cause lymph flow to
increase, balancing the greater rate of fluid outflow from the vascular system
In the thymus, what is the difference in the lymphocyte density of the cortex versus the medulla?
The cortex contains densely packed, rapidly dividing lymphocytes; the medulla contains fewer
Contrast the structure of blood and lymph capillaries
Lymphatic capillaries weave between the tissue cells and blood capillaries. Although similar to blood
capillaries, lymphatic capillaries differ structurally in the following ways: (1) The endothelial cells
forming the walls of lymphatic capillaries are not tightly joined. Their edges loosely overlap one
another, forming flaplike minivalves. (2) Bundles of fine filaments anchor the endothelial cells to
surrounding structures so that any increase in interstitial fluid volume separates the cell flaps, exposing
gaps in the wall rather than causing the lymphatic capillary to collapse. (3) Lymphatic capillaries are
How does the lymphatic system both help and hinder the spread of cancer through the body?
Lymph nodes help rid the body of cancer cells by immune mechanisms. Lymph vessels may also be
used to spread cancer cells throughout the body if immunity is not effective against the cancer cells
How does the structure of a lymph node allow lymphocytes and macrophages to perform their protective
Macrophages ingest microorganisms and cellular debris. Lymphocytes monitor the lymphatic stream
for the presence of antigens and mount an immune response. Because there are fewer efferent
vessels draining the node than afferent vessels that feed it, the flow of lymph through the node
stagnates somewhat, allowing time for the lymphocytes and macrophages to work
Explain the term MALT. What is its function?
MALT is an acronym for mucosa-associated lymphatic tissue. It includes Peyer's patches, the
appendix, and the tonsils in the digestive tract, and lymphoid follicles in the walls of the bronchi.
Collectively, MALT acts to protect these systems from foreign material
How is the skeletal system tied to the lymphatic system?
1. The lymphatic system removes excess fluids in the periostea.
2. The lymphocytes protect the bones from pathogens.
3. Parts of the skeletal system produce the lymphocytes found in the lymphatic system
As the human immunodeficiency virus (HIV) progresses, some individuals develop persistent generalized
lymphadenopathy. Explain why this may occur.
This may occur because lymph nodes are overwhelmed by a large number of virus particles trapped in
the nodes
Describe why the prognosis of cancer is best when there is no detectable spread from the region of the
primary tumor to the lymph nodes
The lymphatic system consists of a meandering network of lymphatic vessels. Cancer cells that break
free from the primary tumor can metastasize via the lymph system
A nurse palpated enlarged lymph nodes. Describe signs and symptoms that help to distinguish cancerous
lymph nodes from infected lymph nodes
Tender nodes are usually due to inflammation, whereas hard, fixed nodes are suggestive of
Lymphedema may occur as a complication after a radical mastectomy, in which lymph nodes have been
removed. Explain why it might occur
Anything that prevents the normal return of lymph to the blood, such as blockage of the lymphatics by
tumors or removal of lymphatics during surgery, results in severe localized edema (lymphedema
While passing through a village on safari you notice a man with one enormous leg and one normal-sized leg.
What could have caused the increased size of the swollen leg?
The man has elephantiasis, which is caused by parasitic worms that get in the lymph system and
reproduce to proportions that block the vessels. The swelling is due to edema
A man involved in a traffic accident is rushed to the emergency room of a hospital with severe internal
bleeding. Examination reveals a ruptured spleen. What is the treatment of choice and what is the likely longterm
outcome (prognosis)?
Surgical removal of the spleen is indicated. The prognosis is very good, as the functions of the spleen
are taken over by the liver and bone marrow
A woman had a mastectomy that included the removal of axillary lymph nodes on her left side. What can she
expect regarding her left arm and why
Removal of the axillary lymph nodes results in severe localized edema since the lymphatic vessels are
also lost. She can expect chronic edema along the arm, although some lymphatic drainage is
eventually reestablished by regrowth of the vessels
A mother takes her son to the doctor and describes the following symptoms that she has observed. The child
is running a fever, has flulike symptoms, and his lymph glands are very swollen and sore to the touch. Of
what significance are the swollen and sore lymph glands?
When tissues are inflamed, such as due to a bacterial infection, lymphatic capillaries develop openings
that permit the uptake of the pathogens. The inflammation and pain indicate lymph nodes infected by
When tissues are inflamed, lymphatic capillaries develop openings that permit uptake of
large particles such as cell debris, pathogens, and cancer cells.
All lymphatic organs are composed of epithelial tissue.
The most important role of the spleen is to provide a site for lymphocyte proliferation and
immune surveillance and response
The simplest lymphoid organs are the lymph nodes.