LYMPATIC SYSTEM LECTURE Flashcards
What is the lymphatic system?
the lymphatic system is a network of vessels that penetrate nearly every tissue of the body and a collection of tissues and organs that produce immune cells
What are the three functions of the lymphatic system?
the three functions of the lymphatic system are fluid recovery, immunity, and lipid absorption
Describe how the lymphatic system promotes fluid recovery.
the lymphatic system absorbs plasma proteins and excess fluid that filters from blood capillaries into the tissue spaces and returns it to the bloodstream by way of lymphatic vessels
How many liters of fluid do lymphatic vessels absorb a day?
lymphatic vessels collect ~2-4 liters of fluid per day
How do lymphatic vessels control the flow of blood?
lymphatic vessels control the flow of blood by one-way valves
What would happen if fluid recovery in the body did not occur?
if fluid recovery did not occur, the circulatory system would not have enough blood
What is a primary symptom of a lack of fluid recovery?
a primary symptom of a lack of fluid recovery is edema/ lymphedema
what is lymphedema?
lymphedema is an accumulation of fluid in a particular part of the body; most commonly the legs
Define elephantiasis.
elephantiasis is when mosquito-borne roundworms infect lymph nodes and block the flow of nymph (fluids)
Describe how the lymphatic system promotes lipid absorption.
in the small intestine, specialized lymphatic vessels absorb dietary lipids that are not absorbed in blood capillaries
Describe how the lymphatic system promotes immunity.
fluids from the capillary beds are filtered and immune cells stand ready to respond to foreign cells or chemical that are encountered
What happens to fluids on the way back into the blood stream?
on the way back to the bloodstream, fluid in lymphatic vessels pass through lymph nodes where the immune cells are waiting
What are dietary lipids called as they are being absorbed by lacteals?
dietary lipids that are being absorbed by lacteals are called chyle
What are specialized lymphatic vessels called?
specialized lymphatic vessels are called lacteals
Describe lymph.
lymph is a clear, colorless fluid similar to plasma but containing less proteins
Describe the purpose of endothelial cells being loosely overlapped in terms of nutrient absorption.
endothelial cells being loosely overlapped allow lymph fluid, small proteins, and bacteria to enter the lymphatic capillaries
Describe lymphatic capillaries.
lymphatic capillaries are closed at one end and tethered to surrounding tissue by protein filaments
Describe the purpose of endothelial cells being loosely overlapped in terms of collecting fluid.
endothelial cells being loosely overlapped create valve-like flaps that open when interstitial fluid pressure is high and close when it’s low
Where are lymphatic capillaries not present?
lymphatic capillaries are absent from bones, teeth, bone marrow, and the nervous system
What is the pressure like in lymphatic vessels?
pressure in lymphatic vessels is low
Describe the anatomy of large lymphatic vessels.
large lymphatic vessels have three layers
What are the three anatomical layers of large lymphatic vessels?
the tunica interna, tunica, media, and tunica externa
Describe the tunica interna layer of large lymphatic vessels.
the tunica interna is where the endothelium and valves are located; the most inner region of the vessel
Describe the tunica externa layer of large lymphatic vessels.
the tunica externa is the thin, external layer of the lymphatic vessel
Describe the tunica media layer of large lymphatic vessels.
the tunica media is consists of elastic fibers and smooth muscle; the middle layer
Describe the route of lymph flow.
lymph flows from the lymphatic capillaries –> collecting vessels –> lymphatic trunks –> collecting ducts
What are the two collecting ducts?
the two collecting ducts are the right lymphatic duct and the thoracic duct
What is the function of the lymphatic trunks?
the lymphatic trunks are responsible for draining major portions of the body
What is the function of the right lymphatic duct?
the right lymphatic duct is responsible for draining lymph from the right arm, right side of the head, and thorax
What are the five major lymphatic trunks?
the five major lymphatic trunks are the paired lumbar, bronchomediastinal, subclavian, the jugular trunks, and the intestinal trunk
Which vein does the right lymphatic duct empty its fluid into?
the right lymphatic duct empties into the right subclavian vein
Describe the thoracic duct.
the thoracic duct is much larger and longer than the right lymphatic duct and begins as a sac in the abdomen
What is the sac in the abdomen called that initiates the thoracic duct?
the abdominal sac that initiates the thoracic duct is called the cisterna chyli
What is the function of the thoracic duct?
the thoracic duct is responsible for draining lymph from the diaphragm, left arm, left side of the head, neck, and thorax
Which vein does the thoracic duct empty into?
the thoracic duct empties into the left subclavian veins
Describe the transport of lymph.
the transportation of lymph is sporadic and slow
Describe the mechanisms of lymph flow.
the skeletal muscles pump and pressure changes in the thorax during breathing, artery pulsations, and rhythmic vessel smooth muscle contractions
What are the to types of lymphocytes?
“t” and “b” cells
Describe lymphocytes (t and b cells).
lymphocytes are the main defense system of the immune system and protect against antigens
What is an antigen?
an antigen is anything that triggers an immune response
Where do “t” lymphocytes (t cells) mature?
“t” lymphocytes mature in the thymus
What are some examples of antigens?
some examples of antigens are bacteria, viruses, mismatched red blood cells, cancer cells, etc.
Where do “b” lymphocytes (b cells) mature?
“b” lymphocytes mature in the bone marrow
What is the function of “t” lymphocytes?
once activated “t” lymphocytes are responsible for managing an immune response by attacking and destroying an infected cell
What is the function of “b” lymphocytes?
“b” lymphocytes are responsible for producing plasma cells that secrete antibodies in blood or other fluids which mark antigens for destruction
What are the three antigen-presenting cells?
the three antigen-presenting cells are macrophages, dendritic cells, and reticular cells
What is the function of dendritic cells?
dendritic cells are responsible for capturing antigens and bringing them to the back to the lymph nodes
What is the function of macrophages?
macrophages are responsible for phagocytizing foreign substances and activating “t” cells
What is the function of reticular cells?
reticular cells are responsible for producing and fiber called stroma
Define stroma.
stroma is a network that supports the other cell types in lymphoid organs and tissues
Where are superficial lymph nodes located?
superficial lymph nodes are located in the cervical, inguinal (groin), and axillary regions of the body
Where are deep lymph nodes located?
Deep lymph nodes are located in the thoracic, pelvic, and abdominal regions of the body
Describe the structure of lymph nodes.
Lymph nodes are typically bean shaped and less than one inch long
What are the connective tissue strands that form lymph node compartments called?
connective tissue strands that form lymph node compartments are called trabeculae
Describe the function of a dense fibrous capsule.
a dense fibrous capsule surrounds nodes from which connective tissue strands extend inward and divide the lymph node into compartments
Define the cortex.
the cortex is the most outer region of a lymph node
Describe the superficial cortex.
the superficial cortex is made up of densely packed follicles
What do the densely packed follicles of the superficial cortex contain?
the densely packed follicles of the superficial cortex contain “b” cells
Describe the deeper cortex.
the deeper cortex houses “t” cells in transit between blood, lymph nodes, and lymph
Define the medulla.
the medulla is the inner/ middle region of the lymph node
What are medullary cords?
medullary cords are thin inward extensions that contain both types of lymphocytes
Where can lymphatic sinuses be found?
lymphatic sinuses can be found throughout the cortex
Define lymphatic sinuses.
lymphatic sinuses are the medulla of the node containing numerous macrophages attached to reticular fibers
Describe the flow of lymph system of nodes.
the lymph nodes receives lymph from several afferent lymphatic vessels that lead into the cortex and medulla sinuses while cleansed lymph leaves the node through efferent lymphatic vessels
What does the term “afferent” mean in reference to lymph flow?
the term “afferent” refers to lymphatic vessels that lead to the lymph node
What does the term “efferent” mean in reference to lymph flow?
the term “efferent” refers to lymphatic vessels that carry lymph away from the lymph node
How many efferent lymphatic vessels does cleansed lymph leave through?
cleansed lymph leaves through 1 to 3 lymphatic vessels
What is the only organ that filters lymph?
lymph nodes are the only organs that filter lymph
How do lymph nodes filter lymph?
lymph nodes contain macrophages (lymphocytes) that remove/ destroy microorganisms and debri
Describe how the filtration process of the lymph nodes can activate an immune response.
lymphocytes (white blood cells) attack foreign antigens and alert immune system of an invasion
Define this clinical condition: lymphadenitis
lymphadenitis is a swollen and painful node that is responding to a foreign invader (antigen)
Describe what happens in an individual with metastatic cancer sites.
in someone with metastatic cancer sites, cancer cells can break loose and enter the lymphatic capillaries to become lodged in the lymphatic nodes
What is the result of a metastatic cancer site?
the result of a metastatic cancer site is a firm, but swollen node; usually painless
What is the function of tonsils?
tonsils are responsible for guarding entrance to the pharynx against inhaled/ ingested pathogens
Describe the tonsils and their accompanying structures.
each tonsil is covered by an epithelium and has deep pits lined by lymphatic nodules
What are the deep pits of the tonsils called?
the pits of the tonsils are called tonsillar crypts
What do pathogens encounter when they enter the tonsillar crypts?
pathogens that enter the tonsillar crypts are met with lymphocytes (white blood cells)
Where are lingual tonsils loacted?
lingual tonsils are located on both sides of the tongue; numerous
Where are tubal tonsils located?
tubal tonsils surround the openings of the auditory tubes into the pharynx
Where is the pharyngeal tonsil located?
the pharyngeal tonsil is located on the wall of the pharynx just behind the nasal cavity; only one
Where are the palatine tonsils located?
the palatine tonsils are located at the posterior margin of the oral cavity
Which tonsil is the largest and most often infected?
the palatine tonsil is the largest and most often infected tonsil
What is another name for the pharyngeal tonsil?
another name for the pharyngeal tonsil is the “adenoid” tonsil
Define a tonsillectomy.
a tonsillectomy is the surgical removal of the tonsils
Where is the thymus loacted?
the thymus is located between the sternum and aortic arch
The thymus is a part of which system(s)?
the thymus is a part of both the endocrine and lymphatic system
What is the function of the thymus?
the thymus is responsible for housing developing “t” lymphocytes and secreting hormones that regulate their later activity
Describe the development of “t” lymphocytes.
during development “t” lymphocytes are protected from foreign antigens until they are mature and enter the blood or lymphatic vessels
which barrier protects developing “t” cells from foreign antigens?
the blood-thymus barrier protects developing “t” cells from foreign antigens
What is the function hormone secretions from the thymus?
the thymus’ hormone secretions promote the development and action of “t” cells
What are the three hormones that the thymus secretes?
the thymus secretes thymosin, thymulin, and thymopoietin
Describe the size of the thymus relative to the age of the individual.
the thymus is very large in the fetus and grows slightly after childhood; after 14 years old it decreases in size until it become very small in adulthood
What happens if the thymus is removed prematurely?
if the thymus is removed prematurely the individual would never develop immunity
Describe both the anatomy and anatomical positioning of the spleen.
the spleen is the size of a fist and is located inferior to diaphragm on the left side of the heart
What is the largest lymphatic organ in the body?
the largest lymphatic organ is the spleen
What is a hilum?
a hilum is a place where blood vessels enter/ exit an organ
Describe how blood is supplied to the spleen.
blood is supplied to the spleen by the large splenic artery/ vein that enter/ exit through the hilum
What are the two major anatomical sections of the spleen?
the two major anatomical sections of the spleen are the red pulp and white pulp
Describe the red pulp of the spleen.
the red pulp of the spleen is made up of sinuses gorged with red blood cells
What is the function of the red pulp?
the red pulp is responsible for producing erythrocytes in the fetus and adults with anemia; it is also where erythrocytes are disposed of
How are old red blood cells disposed of within the spleen?
old erythrocytes are engulfed by macrophages which are also located in the spleen
Describe the anatomy of the white pulp in the spleen.
white pulp is made up of lymphocytes and macrophages suspended on reticular fibers along small branches of the splenic artery
What is the function of the white pulp of the spleen?
the white pulp filters blood for foreign antigens similarly to how lymph nodes filter lymph
What does the acronym MALT stand for?
“malt” stands for mucosa-associated lymphoid tissue
What is mucosa-associated lymphoid tissue (malt)?
mucosa-associated lymphoid tissue is a set of distributed lymphoid tissues that are strategically located in mucous membranes throughout the body
Where are the largest quantities of mucosa-associated lymphoid tissue located?
the largest quantities of mucosa-associated lymphoid tissue are located in the tonsils, peyers patches, and appendix
What are peyers patches?
peyers patches are large clusters of lymphoid follicles that are similar to tonsils
Where are peyers patches found?
peyers patches are found in the wall of the distal portion in the small intestine
What is the appendix?
the appendix is a tubular offshoot of the first part of the large intestine that contains a high concentration of lymphoid follicles
What is the function of the appendix?
the appendix prevents bacteria and other pathogens commonly found in the large intestine from entering the very vascular small intestine
Where can smaller collections of mucosa-associated lymphoid tissue be found?
smaller collections of mucosa-associated lymphoid tissue are found in the mucosa of the respiratory system and genitourinary tract organs and the digestive tract
