Chapter 20 Lymphatics Flashcards
A hematopoietic stem cell will give rise to ______
- ertthrocytes
- leukocytes
- platelets
- all of the above
Predict the outcome of an overdose of the hormone erythropoietin
- The blood viscosity increases to levels that may induce heart attacks or strokes.
- The oxygen-carrying capacity remains unchanged despite elevated red blood cell counts.
- Red blood cell counts remain unchanged, but the number of reticulocytes increases.
- Blood viscosity levels decrease while oxygen-carrying capacity increases.
If a patient has pernicious anemia, the inability of the body to absorb vitamin B12 the patient ______
- would have reduced blood iron levels
- would have a decreased number of red blood cells
- would have increased levels of hemoglobin
- would not experience any effects on red blood cells
Lymphatic system
- a network of vessels that absorbs fluid that leaks from the blood into surrounding tissues
- about 3 liters of fluid leak out each day
- if leakage continued unchecked the body would swell with fluid
3 parts of the lymphatic system
- network of lymphatic vessels (lymphatics)
- lymph- fluid
- lymph nodes, tissues, and organs
functions of the lymphatic system
- returns interstitial fluid and leaked plasma proteins back to the blood
- once interstitial fluid enters lymphatics, it is called lymph (clear water)
- ONE WAY SYSTEM
- brings fluids back to the heart to reintroduce to the circulatory system
- together with lymphoid organs and tissues, provide the structural basis of the immune system
right lymphatic duct and thoracic duct
-bring lymphatic fluids to the heart to be reintroduced to the circulatory system
lymphatic vessels
- one way system
- lymph flows TOWARDS the heart
- lymphatic capillaries
- lymphatic collecting vessels
- lymphatic trunks and ducts
lymphatic capillaries
- the smallest
- similar to blood capillaries except they are very permeable (take up cell debris, pathogens, and cancer cells)
- endothelial cells overlap to form one-way minivalves
- lacteals- specialized lymph capillaries present in small intestines -> absorb digested fat and deliver fatty lymph (chyle) to the blood
- anchored by filaments to connective tissues
- increased interstitial fluid pressure -> minivalves open -> take in lymph fluid -> bring back to heart
- blind ended tubes in which adjacent endothelial cells overlap each other, forming flaplike minivalves
lymphatic collecting vessels
- similar to veins except have thinner walls
- more internal valves
- anastomose more frequently
- collecting vessels in the skin travel with superficial veins
- deep collecting vessels travel with arteries
anastomose
- different structures connect together in the same space
- ex. venous and arterial blood flow collides
lymph nodes
- collections of lymph structures that follow the lymphatic system
- organized in clusters
- cervical nodes- neck, infection, sickness
- axillary node- armpit, breast cancer
- inguinal nodes- filter blood from the legs
lymphatic trunks
- formed by the union of the largest collecting ducts
- largest
- paired lumbar
- paired bronchomediastinal
- paired subclavian
- paired jugular trunks
- a single intestinal trunk
- lymphatic capillaries -> collecting vessels -> trunks -> ducts
cisterna chyli
-bulbous piece
lymphatic ducts
- lymph is delivered into one of two large ducts
- right lymphatic duct
- thoracic duct
- each empties lymph into venous circulation at the junction of the internal jugular and subclavian veins on its own side of the body
right lymphatic duct
-drains the right upper arm and the right side of the head and thorax
thoracic duct
-arises from the cisterna chyli (large sac) and drains the rest of the body
what propels blood throughout the body
- the heart
- lymph does not have anything pumping it
- lymph system is low pressure
lymph transport
- lymph is propelled by:
- pulsations of nearby arteries
- contractions of smooth muscle in the walls of the lymphatics
- milking action of active skeletal MM
- pressure changes in the thorax during breathing
- lacks and organ to act as pump, low pressure vessels
lymphoid cells
- lymphocytes the main warriors of the immunes systems
- two main varieties-
- t cells (t lymphocytes)- thymus, attack interstitial invaders
- b cells (b lymphocytes)- bone marrow, attack outside invaders
lymphocytes
- t cells and b cells protect against antigens- anything percieved as foreign
- ex. bacteria and their toxins, viruses & mismatched RBCs or cancer cells
- t cells attack and destroy foreign cells
- b cell produce plasma cells which secrete antibodies
macrophages
- lymphoid cells
- phagocytize foreign substances and help activate t cells
dendritic cells
- lymphoid cells
- capture antigens and deliver them to lymph nodes
- also activate T cells
reticular cells
- lymphoid cells
- produce lymphoid tissues stroma (mattress) that supports other cells in lymphoid organs
_____ can enter lymphatic capillaries
- bacteria
- large proteins
- interstitial fluid
- all of the above****
- B and C only
- Name the 4 types of lymph vessels and 2. What is the difference between the right lymphatic ducts and the thoracic duct
- capillaries, collecting vessels, trunks, ducts
- right lymphatic duct drains right axillary, right upper extremities, right side of face, … thoracic duct drains everything else
B cells
- b lymphocytes)-
- made in bone marrow
- attack outside invaders
- b cells produce plasma cells which secrete antibodies
T cells
- t lymphocytes
- made in thymus
- attack interstitial invaders
- attack and destroy foreign cells
lymphoid tissues
- houses and provides a proliferation site for lymphocytes
- furnishes a surveillance vantage point
- two types:
- diffuse lymphatic tissue
- lymphatic follicles
diffuse lymphatic tissue
- found in every organ in body
- made of loose reticular CT
- larger collections appear in mucous membranes (digestive tract) and lymphoid organs -> where illness can be caused
lymphatic follicles (nodules)
- solid, spherical bodies of tightly packed reticular elements and cells
- germinal center composed of dendritic and B cells (enlarge when b cells are dividing and producing plasma cells)
- may form part of larger lymphoid organs (lymph nodes
- no T cells (only B)
lymph organs
- primary lymph organs are where B and T cells mature
- B cells mature and red bone marrow
- T cells mature in thymus (in lungs and heart)
secondary lymph organs
- where lymphocytes encounter their antigens and are activated
- lymph nodes
- spleen
- MALT (mucosa-associated lymphoid tissue) -> tonsils, appendix, peyer’s patch (small intestine)
lymph nodes
- principle lymphoid organs of the body
- embedded in connective tissue, in clusters along lymphatic vessel
- most numerous and doing most of the work
- near the body surface in inguinal axillary, and cervical regions of the body
- follow the lymph system
functions of lymph nodes
- filter lymph- macrophages destroy microorganisms and debris
- immune system- lymphocytes are activated and mount and attack against antigens
structure of a lymph node
- bean shaped
- external fibrous capsule
- nodes are divided into compartments
- two histologically distinct regions
- cortex- germinal centers, follicles
- cortex contains follicles with germinal centers (heavy with dividing B cells)
- medulla- macrophages
- medullary sinuses contain macrophages!
- t cells circulate continuously among the blood, lymph nodes, and lymphatic stream
- surrounded by a dense fibrous capsule with an internal framework, or stroma, of reticular fibers that supports the lymphocyte
afferent lymphatic vessels
5
- more afferent vessels
- bringing in lymph fluid into the lymph node
efferent lymphatic vessels
2
-lymph fluid exits the lymph nodes
circulation in the lymph nodes
- lymph
- enters via afferent lymphatic vessels
- travels through large subcapsular sinus and smaller sinuses
- exits the node at the hilum via efferent vessels
- fewer efferent vessels, causing flow of lymph to stagnate, allowing lymphocytes and macrophages time to carry out functions
- there are more afferent than efferent meaning more is being brought in than is leaving -> increases the amount of time the lymph spends in the lymph node -> allows more time for macrophages and break down and neutralize pathogens -> more efficient
enlarged lymph nodes
can be a sign of:
- fever
- fatigue
- sore throat
- swollen lymph glands
- infected lymph nodes- buboes
- obvious symptoms of bubonic plague, black death that killed much of europe during the middles ages
lymph nodes and cancer
- primary site- hoddgkins lymphoma or non-hodgkins lymphoma- swollen lymph nodes (not painful), fatigue and fever
- secondary site- cancer spreads via lymph-to-lymph nodes
- cancer spreads through the lymph system
- sentinel node- the 1st node from cancer site, tested for metastatic disease -> how to tell if the cancer is spreading
breast cancer and lymphedema
- one of the most common causes of lymphedema is removal of the breast (mastectomy) and underarm lymph tissue
- issue with the lymph system will cause swelling
- if you remove lymph nodes with a mastectomy the lymph will be drained less causing swelling
lymph tends to stall inside lymph nodes. this is due to ____
- small diameter spaces within the medulla
- the large volume of lymph entering the node
- fewer efferent lymphatic vessels than afferent lymphatic vessels*
- fewer afferent lymphatic vessels than efferent lymphatic vessels
what cells populate the germinal centers of lymphoid follicles
- t lymphocytes
- b lymphocytes*
- reticular cells
- macrophages
- dendritic cells
spleen
- largest lymphoid organ, size of your first
- served by splenic artery and vein, which enter an exit at the hilus
- contains lymphocytes, macrophages, and huge numbers of erythrocytes
spleen functions
- stores breakdown products of RBCs (iron) for later reuse
- stores blood platelets
- site of fetal erythrocytes production (normally ceases after birth)
- cleanses the blood of aged cells and debris
- site of lymphocyte proliferation and immune surveillance and response
structure of the spleen
- white pulp near central arteries- house lymphocytes- immunity
- red pulp in sinuses which houses macrophages- blood filtering
- splenic artery and vein enter via hilum- indented part of spleen
- surrounded by a fibrous capsule and contains both lymphocytes found in white pulp and macrophages found in red pulp.
splenomegaly
- enlargement of spleen due to accumulation of infectious microorganisms
- typically, from mononucleosis, malaria, and leukemia
thymus
-changes size with age
-increases in size and is most active during childhood
-stops growing during adolescence and then gradually atrophies
-differs from other lymphoid organs
-functions strictly in T lymphocyte maturation (not B cells)
-it does not directly fight antigens
-these thymocytes provide the environment in which T lymphocytes become immunocompetent (ability to start immune response)
-made up of thymic lobules containing an outer cortex and an inner
medulla.
-no B cells and, therefore, no follicles, it is not directly involved in fighting antigens
-stroma of the thymus consists of epithelial cells, not reticular fibers.
an advantage to having reticular connective tissue present in lymph nodes is that _________
- the loose organization of reticular connective tissue provides niches for macrophages and lymphocytes***
- lymph filters through the nodes and is exposed to lymphocytes and macrophages
- lymphocytes cycle to various areas of the body and back to lymph nodes
- all of the above take place
red pulp of the spleen is most concerned with ______, while white pulp is most concerned with ________
- immunity; new red blood cell formation
- filtering lymph; lymphocyte proliferation
- blood filtering; immunity***
- urine formation; blood filtering
MALT
- mucosa-associated lymphatic tissue, including (lymphoid tissue located in mucous membranes)
- peyer’s patches (small intestine), tonsils, and the appendix (offshoot of large intestine)
- lymphoid nodules in the walls of the bronchi (respiratory tract)
- protects the digestive and respiratory system from foreign matter
aggregates of lymphoid follicles: peyers patches
- clusters of lymphoid follicles
- in the wall of the distal portion of the small intestine
aggregates of lymphoid follicles: appendix
- tubular offshoot of LARGE intestine
- high concentration of lymphoid follicles
- vermiform appendix- worm shaped
- houses helpful bacteria for intestine
- lymph tissue accumulates after birth until 2nd/3rd decade
peyers patches and appendix
- both destroy bacteria, preventing them from breaching the intestinal wall
- generate memory lymphocytes
- cleanse digestive tract of bacteria
- if digestive material leaks it would cause bad sepsis
tonsils
- simplest lymphoid organ
- form a ring of lymphatic tissue around the pharynx
- contain follicles with germinal centers
- are not fully encapsulated
- epithelial tissue overlying tonsil masses invaginates, forming tonsillar crypts
- crypts trap and destroy bacteria and particulate matter that enter the pharynx in food and inhaled air
- palatine tonsils- at posterior end of the oral cavity
- lingual tonsils- grouped at the base of the tongue
- pharyngeal tonsil (adenoids)- in posterior wall of the nasopharynx
- tubal tonsils- surrounding the openings of the auditory tubes into the pharynx
tonsillitis
- bacterial vs viral
- strep throat- contagious bacterial infection with sore throat, pus on tonsils, fever and enlarged lymph nodes
why is the lymphatic system one way
- takes all the lymph and takes it back to the heart to deposit back to circulatory system
- never takes fluid away from the heart
how do lymphatic capillaries differ from blood capillaries
- more permeable
- thinner
- one way valves
- when interstitial pressure increases lymph enters
areas of the body that are more densely clustered
- cervical
- axillary
- inguinal
