Chapter 20 Lymphatic System
Lymph capillaries can also take up
- Cell debris - Pathogens disease causing agent - Cancer cells - Proteins
Peyer's patches and the appendix:
- Destroy bacteria, preventing them from breaching the intestinal wall - Generate "memory" lymphocytes for long-term immunity
Lymphatic vessels (lymphatics)
- Elaborate network of drainage vessels - Circulates ~ 3L interstitial fluid per day
Lymphoid tissue main functions
- Houses and provides proliferation sites for lymphocytes - Offers surveillance vantage points for lymphocytes and macrophages as they filter through lymph
Size of the THYMUS varies with age:
- In infants, neck and extends the heart - It increases in size and most active during childhood - It stops growing during adolescence - then gradually atrophies
Names of the regions of the body that the LYMPHATIC TRUNK drain
- Lumbar pair - Bronchomediastinal pair - Subclavian pair - Jugular trunk pair -Intestinal trunk single
Lymph vessels (lymphatics) include:
- Lymphatic capillaries (thin walled close ended tubes in capillary bed) - Larger lymphatic vessels (largest are trunks and ducts)
Other Lymphoid Cells
- Macrophages - Dendritic cells - Reticular cells
Medulla
- Medullary cords extend inward from cortex and contain B cells, T cells, and plasma cells - Lymph sinuses contain macrophages
Lymph is propelled by same mechanisms:
- Milking action of skeletal muscle - Pressure changes in thorax during breathing - Valves to prevent backflow - Pulsations of nearby arteries - Contractions of smooth muscle in walls of lymphatics
Lymph is delivered from the TRUNKS into one of two LYMPHATIC DUCTS
- Right lymphatic duct - Thoracic duct
Cortex
- Superficial area of cortex contains follicles with germinal centers that are heavy with dividing B cells - Deep cortex houses T cells in transit * T cells circulate continuously among blood, lymph nodes and lymph - Dendritic cells nearly encapsulate the follicles
Lymphocytes mature into one of two main types
- T cells also called T Lmyphocytes - B cells also called B Lymphocytes
Other lymphoid organs
- Tonsil ( in pharyngeal region) - Thymus ( in thorax; most active during youth) - Spleen (curves around left side of stomach) - Peyer's patches (in intestine) - Appendix
Structure of lymph nodes
- Vary in shape and size but most are bean shaped * Small, less than 2.5 cm (~1 inch) - Surrounded by external fibrous capsule - Capsule fibers extend inward as trabeculae that divide node into compartments - Two histologically distinct regions of node: * Cortex * Medulla
Lymphatic vessels consist of 3 collecting vessels
- Vessels - Trunks - Ducts
Lymphoid cells consist of
1 immune system cells found in lymphoid tissue and 2 supporting cells that form lymphoid tissue structures
2 basic functions of lymph nodes
1. Cleansing the lymph: act as lymph "filters" (Macrophages remove and destroy microorganism and debris that enter lymph) 2. Immune system activation: offers a place for lymphocytes to become activated and mount and attack against antigens
Two main types of lymphoid tissue
1. Diffuse lymphoid tissue 2. Lymphoid follicles
Circulation in the Lymph Nodes
1. Lymph enters convex side of node via afferent lymphatic vessels 2. Travels through large subcapsular sinus and ghen into smaller sinuses found throughout cortex and medulla 3. Exits the node at the hilus via efferent vessels 4. Fewer efferent vessels, causing flow of lymph to stagnate, allowing lymphocytes and macrophages time to carry out functions 5. Lymph passes through several nodes before going back to the blood
Lymphatic system consists of two overlapping divisions
1. Lymphatics 2. Organs and tissues
Three additional functions of spleen
1. Stores breakdown products of RBCs (e.g., iron) for later reuse 2. Stores blood platelets and monocytes for release into blood when needed 3. May be site of fetal erythrocyte production (normally ceases after birth)
Two distinct areas of the spleen:
1. White pulp - contains mostly lymphocytes 2. Red pulp - concerned with disposing of worn-out RBCs and pathogens
The principal lymphoid organs
Aggregations occurs near the body surface in inguinal, axillary, and cervical
Cisterna chyli
An enlarged pouch on the thoracic duct that serves as a storage area for lymph moving toward its point of entry into the venous system
Lymphadenopathy
And disease of the lymph nodes
Lymphoma
Any neoplasm (tumor) of the lymphoid tissue, whether benign or malignant
Lymphedema caused by
Anything that prevents normal return of lymph to blood
________ can enter lymph capillaries
Bacteria, large proteins, and interstitial fluid
What was named after chief clinical feature of this disease
Bubonic plague
Lymphocytes
Cells of the adaptive immune system (main warriors)
Lymph capillaries drain into increasingly larger vessels called
Collecting lymphatic vessels
Lymphangitis is
Condition in which lymphatic vessels appear as painful red lines under the skin
• Internally, tonsils contain invaginations known as
Crypts (trap and destroy bacteria and particulate matter)
___________ have many appendages like tree branches, and collect antigens to deliver to lymph nodes for recognition by immune cells.
Dendritic cella
Lymphangiography
Diagnostic procedure in which the lymphatic vessels are injected with radiopaque dye and then visualized with X rays
Right lymphatic duct
Drains right upper arm and right side of head and thorax
Thoracic duct
Drains to the rest of the body
Lymphatic ducts
Each empties lymph into venous circulation at the junction of the internal jugular and subclavian veins on its own side of the body
Splenomegaly
Enlargement of the spleen due to accumulation of infectious microorganisms, malaria, or leukemia
MALT - mucosa-associated lymphatic tissue:
Found in mucosa of respiratory tract, genitourinary organs, digestive tract; - tonsils - appendix (digestive tract) - Peyer's patches (digestive tract) - Lymphoid nodules in the walls of the bronchi (respiratory tract)
Thymus secretes
Hormones (thymosin and thymopoietin) that cause T cells to become immunocompetent - Functions strictly in T lymphocyte maturation - Does not directly fight antigens
Nodes and other organs
House phagocytes and function in defense and disease resistance (immune) - Includes: Tonsils, Lymph nodes, Thymus, Bone marrow, and Spleen
Your patient has had her spleen removed after it was ruptured in a motorcycle accident. Which of the following is your greatest concern for her future health status?
Infection
Buboes
Inflames, swollen, tender lymph nodes that result when nodes are overwhelmed by what they are trying to destroy
Lyphangitis caused by
Inflammation of larger lymphatic vessels that contain vaso vasora
Tonsillitis
Inflammation of the tonsils, typically due to bacterial infection. Tonsils become red, swollen, and sore.
Fluids that was force out of the capillaries by HP (can be 3 liters/day!)
Interstitial fluid
Hodgkin's lymphoma
Is a type of lymphoma in which cancer originates from a specific type of white blood cells called lymphocytes. Symptoms may include fever, night sweats, and weight loss. Often there will be non-painful enlarged lymph nodes in the neck, under the arm, or in the groin
Non-Hodgkin's Lymphoma
Is cancer that originates in your lymphatic system, the disease-fighting network spread throughout your body a tumor develop from lymphocytes
Hypoalbuminemia is a medical condition in which blood plasma levels of albumin are abnormally low. One cause of this disorder is the increased movement of plasma albumin into the interstitial space through leaky blood capillaries. How would this condition affect the volume of lymph that is produced?
It would increase lymph volume.
Spleen
Largest lymphoid organ - Location: LEFT SIDE beneath diaphragm
Pharyngeal tonsils
Located at the posterior wall of the nasopharynx. These are referred to as the adenoids if they are enlarged
Diffuse lymphoid tissue
Loose arrangement of lymphoid cells and some recticular fibers found in virtually every body organ
Once it is picked up by lymph vessels
Lymph
Which statement correctly describes the origin of lymph fluid?
Lymph is excess tissue fluid formed from plasma that has leaked from capillaries
Small organs intimately associated with lymphatic vessels
Lymph nodes
Blind-ended vessels that weave between tissue cells and blood capillaries
Lymphatic capillaries
Offers a one-way system, ensuring lymph flows only toward heart
Lymphatic vessels
Select the correct statement about lymphoid tissue.
Lymphoid tissue is predominantly reticular connective tissue.
T cells mainly
Manage immune response and some also attack and destroy infected cells
Lingual tonsils
Paired, located at the base of the tongue
Palatine tonsils
Paired, located on either side at the posterior end of the oral cavity (largest and most commonly infected tonsils).
Found in the wall of the distal portion of the small intestine
Peyer's patches
Isolated clusters of lymph follicles found in the wall of the small intestine.
Peyer's patches
Macrophages
Phagocytize foreign substances and help activate T cells
Lymph nodes is
Principal secondary lymphoid organs of the body there are 100 of nodes throughout the body
B cells mainly
Produce plasma cells which secrete antibodies - Antibodies mark antigens fro destruction by phagocytosis
Recticular cells
Produce reticular fiber called stroma in lymphoid organs
T cells and B cells
Protect against antigens (anything the body perceives as foreign) - Examples: Bacteria, Virus, Toxins, Fungi, Cancer, Mismatch RBCs, Cancer cells, and Protozoa
MALT
Protects the digestive and respiratory systems from foreign matter
Lymph
Protein-containing fluid within lymphatic vessels.
Lymphoid organs and tissues
Provide structural basis of immune system by housing phagocytic cells and lymphocytes
Lymphoid tissue are largely composed of
Recticular connective tissues ( chicken wire of the lymphatic system) a type of loose connective tissue
Lymphatic System
Returns fluids leaked from blood vessels back to blood
Lymphedema
Severe localized edema
Lymphatic capillaries
Similar to blood capillaries except EXTREMELY PERMEABLE and endothelial cells overlap (like shingles) to form minivalves
Dendritic cells
Spiny-looking cells that capture antigens and deliver them to lymph nodes; also help activate T cells
Stores blood platelets
Spleen
Splenectomy
Surgical removal or ruptured spleen
Tubal tonsils
Surround the openings of the auditory tubes into the pharynx
Structure of the Spleen
Surrounded by a fibrous capsule, it has trabeculae that extend inward and contains lymphocytes, macrophages, and huge numbers of erythrocytes RBCs
Condition of Boboes
Swollen glands and are sometimes pus-filled
The thymus is important for
T lymphocyte maturation
Sentinel node
The first node that receives lymph drainage from a body area suspected of being cancerous
What is the main function of the lymphatic system?
The lymphatic system returns leaked fluid and plasma proteins that escape from the bloodstream to the blood.
Which of the statements best explains the presence of red streaks on Andrew's forearm?
The lymphatic vessels of his forearm are inflamed.
A patient's deep hand laceration was sutured at your clinic yesterday. When you make a follow-up call today, the patient reports "some red streaks on my forearm." Why are you concerned?
The red streaks suggest lymphangitis, which occurs when the blood vessels that supply inflamed lymphatic vessels (vasa vasorum) become congested with blood. You are concerned that the patient's wound is infected by bacteria.
Which lymphoid organ extracts aged and defective blood cells and platelets from the blood in addition to storing some of the breakdown products for later reuse?
The spleen harbors macrophages that ingest and recycle materials from erythrocytes that have aged or become damaged.
Which of these lymphoid organs is part of a collection of tissues called the mucosa-associated lymphoid tissues (MALT) and removes pathogens entering the pharynx (throat)?
The tonsils function to protect the throat and surrounding tissues from infection via the mouth and nose.
Lymphatic trunks are formed by
The union of the largest collecting vessels and drain to the large areas of the body
Which of the following is a role of lymph nodes?
They filter lymph.
The day after Andrew's surgery, the lymph nodes in his right armpit become enlarged and tender. This was most likely caused by which of the following?
This is due to infection of his lymph nodes by bacteria.
The thymus is the only lymphoid organ that does not DIRECTLY fight antigens.
True
When tissues are inflamed, lymphatic capillaries permit uptake of large particles such as cell debris, pathogens, and cancer cells.
True
Elephantiasis
Typically a disease in which the lymphatics become clogged with parasitic roundworms, an infectious condition called filariasis
Types of Tonsils:
a. Palatine b. Lingual c. Pharyngeal d. Tubal
Lymphangitis is caused by ______.
an infection
Which of the following represents a logical sequence of structure that contribute to return of fluid to the blood via the lymph
arteries; blood capillaries; lymphatic vessels; subclavian vein
Which of the following would the body perceive as an antigen
bacteria, virus, and mismatched red blood cell
Red pulp of the spleen is most concerned with ___________ while white pulp is most concerned with ________
blood filtering..... immunity
Lymphatic capillaries are NOT found in __________.
bone marrow
The prefix _____ means juice.
chyl-
Liquefied fat, called _________, is carried by lacteals from the small intestine to the blood stream.
chyle
Lymphatic vessels
collect leaked fluids from interstitial spaces
The prefix _____ means resembling a tree
dendr-
Which of the following lymphoid cells trap antigens and transport them to lymph nodes?
dendritic cells
Where are Peyer's patches located?
distal portion of the small intestine
Lymph vessels do NOT transport ________.
erythrocytes
Lymph tends to stall inside lymph nodes this is due to
fewer efferent lymphatic vessels than afferent lymphatic vessels
The highest density of lymph node can be found
guarding the trunk of the body
Peyer's patches
isolated clusters of lymphoid tissue, similar to tonsils - Similar structures are also found in the appendix
Fats absorbed from the small intestine are transported to the bloodstream via ________.
lacteals
The prefix _____ means lymph, lymphatic
lymph-
Vessels that collect excess tissue fluid and return it to the blood stream are called ___________.
lymphatics
Within buboes, bacteria are directly attacked by ______.
macrophages
The prefix ______ means middle
med-
Both types of lymphocytes are found in the __________, which are inward extensions of cortical lymphoid tissue in lymph nodes.
medullary cord
Which of the following contributes to flow of lymph through vessels
milking action of skeletal muscle and pressure changes in the thorax
Lymphatic capillaries owe their permeability to the presence of
minivalves in their walls
Which lymphoid cells produce antibodies?
plasma cells
Which of these is not a function of the lymph node
produce red blood cells in special cases
Lacteals
specialized lymph capillaries present in intestinal mucosa and absorb digested fat and deliver fatty lymph (chyle) to the blood
Largest lymphatic organ.
spleen
Which of the following lymphoid tissues removes defective red blood cells from the blood
spleen
What anatomical area(s) is/are protected by the tubal tonsils?
the passage from the pharynx to the middle ear
Receives lymph from most of the body
thoracic duct
Which lymphoid organ atrophies as we age?
thymus
Which lymphoid organ(s) serve(s) as the site where T lymphocytes become immunocompetent T cells?
thymus gland
Tonsils promote memory of pathogens by
trapping pathogens to develop immune cells with memory.
Thymus
• A bilobed lymphoid organ
Lymphatics system consists of 3 parts
• Network of Lymphatic vessels (lymphatics) pipes • Lymph (fluid in vessels) • Lymph nodes (organs associated with vessels and cleanse lymph)
Main function of SPLEEN
• Site of lymphocyte proliferation and immune surveillance and response • Cleanses the blood of aged cells and platelets, and debris; macrophages remove debris
Organs and Tissues consists of
• Spleen • Tonsils • Thymus • Organs throughout body
Tonsils
• The tonsils gather and remove pathogens entering the pharynx via food or inhaled air. - Simplest lymphiod organ
