The Lymphatic System Flashcards
What is homeostasis?
A state of equilibrium within the body with respect to the functions and composition of fluids and tissues
What is a pathogen?
A disease producing microbe
What is the lymphatic system responsible for?
Our defense against pathogens
What two systems does the lymphatic system work closely with?
The cardiovascular system and digestive system
What is a lymphocyte?
An agranular leukocyte involved in immune response
What are two examples of lymphocytes?
T cells and B cells
What is a monocyte?
An agranular leukocyte that performs phagocytosis in the blood
What is a macrophage?
An agranular leukocyte that performs phagocytosis in the tissues
What is the difference between a monocyte and a macrophage?
A monocyte functions in the blood, when it migrates to the tissues it becomes a macrophage
What is a fibroblast?
Contributes to the formation of connective tissues
What is a virus?
A non living organism that infects cells and replicates within. It requires a host to survive
What is bacteria?
A living organism that does not require a host to survive
What is the difference between a virus and bacteria?
Viruses are non living and require a host, and bacteria is living and does not require a host
What are cell identity markers?
A type of membrane protein that allows cells to recognize itself vs. foreign cells
What is cytolysis?
Destruction of a cell caused by increased fluid. The cell bursts due to the amount of fluid.
What kind of solution does cytolysis occur in?
Hypotonic solutions.
What is apoptosis?
The self destruction of a cell
What is parenchyma?
Functional tissue
What is stroma?
Structural tissue
What is lymph?
Interstitial fluid that flows within lymphatic vessels
What is lymphatic tissue?
Connective tissue with a large quantity of lymphocytes
What are lymphocytes?
Agranular WBCs
What is the difference between lymphatic vessels and small veins?
Although similar in structure, lymphatic vessels have thinner walls and more valves
What is found along the tract of lymphatic vessels?
Lymph nodes
Where are lymphatic vessels of the skin found?
In the subcutaneous layer
What route does the lymphatic vessels of the skin follow?
Typically follows the same route as veins
What route does the lymphatic vessels of the viscera follow?
Typically follows arteries and form plexuses around them
Where are lymphatic capillaries located?
In the spaces between the cells
Why do lymphatic capillaries have a greater permeability than blood capillaries?
To absorb larger molecules like proteins and lipids
What is different about the structure of lymphatic capillaries than blood capillaries?
Closed off at one end, slightly larger in diameter, and a one way structure for the inflow of interstitial fluid
What happens when the pressure of interstitial fluid is higher than in the capillaries?
Overlapping endothelial cells separate slightly
What happens when the pressure is higher in the capillaries?
The cells adhere more closely
What is attached to lymphatic capillaries?
Anchoring filaments
What do anchoring filaments do?
Secure the vessels to the surrounding tissue
How do anchoring filaments aid in the flow of interstitial fluid?
When there is an increase of interstitial fluid, the anchoring filaments are pulled and create an opening between the endothelial cells, increasing inflow
What are lacteals?
Specialized lymphatic capillaries in the small intestine that carry dietary lipids into lymphatic vessels
What tissues lack lymphatic capillaries?
Avascular tissue, portions of the spleen, and red bone marrow
What are lymph trunks?
When lymphatic vessels exit lymph nodes in specific regions of the body they unite to form trunks
What are lymph trunks responsible for?
draining lymph from the lymphatic vessels into the venous system
How do lymph trunks return lymph on the right side of the body?
Independently drain at the junction of the internal jugular and subclavian vein
How do lymph trunks return lymph on the right side of the body?
Thoracic duct drains at the junction of the internal jugular and subclavian vein
What vein returns lymph from the upper right quadrant of the body?
The right brachiocephalic vein
What vein returns lymph from the upper left quadrant and the entire body below the diaphragm?
The left brachiocephalic vein
What filters freely out of capillaries to form interstitial fluid?
Most components of blood plasma (nutrients, gases, hormones)
What does the excess fluid that drains into lymphatic vessels become?
Lymph
Why does interstitial fluid contain low levels of proteins?
Because plasma proteins are typically too large to exit the blood vessels
What path does the flow of lymph follow?
Blood capillaries -> interstitial space -> lymphatic capillaries -> lymphatic vessels -> lymphatic trunks/ducts, junction of internal jugular/subclavian veins
What are the two mechanisms that pump lymph back into the venous system?
The respiratory and skeletal pumps
How does the respiratory pump function?
Inhalation and exhalation changes the pressure within the vessels while one way valves within the vessels prevent backflow
How does the skeletal pump function?
The ‘milking action’ of the skeletal muscle contractions compress lymphatic vessels and forces lymph in the right direction
What are the two groups of lymphatic organs and tissues?
Primary and secondary
What is the function of primary lymphatic organs?
The sites where stem cells divide and become immunocompetent (capable of mounting an immune response)
What is the function of secondary lymphatic organs?
The sites where most immune responses occur
What are examples of primary lymphatic organs?
Red bone marrow and the thymus
What are examples of secondary lymphatic organs?
Lymph nodes, the spleen, and the lymphatic nodules
Where is red bone marrow located?
In the flat bones and the epiphyses of long bones
What occurs in red bone marrow?
Immature stem cells become immunocompetent B cells and pre T cells
Where do pre-T cells become immunocompetent T cells?
In the thymus
Where do matured T cells go after the thymus?
Move to the medulla, then the blood stream to lymph nodes, the spleen, and other lymphatic tissues
How many lymphatic vessels are scattered within the body?
Approximately 600
What are the functions of the lymph nodes?
Filtering lymph and activating immune response
What is a lymph node surrounded by?
A dense connective tissue capsule
What are trabeculae?
Extensions off the capsule that divide the node into compartments and provides a route for blood vessels
What is the parenchyma of a lymph node divided into?
A superficial cortex (inner and outer) and a deep medulla
What is in the outer cortex?
Lymphatic nodules, aggregates of B cells
What is in the inner cortex?
Mostly T cells, no lymphatic nodules
What is in the medulla?
B cells, macrophages
Where does lymph enter a lymph node?
The afferent lymphatic vessels
Where does lymph then filter through after entering the lymph node?
Several sinus, subcapsular->trabecular-> medullary
Where does the lymph exit the lymph node?
The efferent lymphatic vessels
Why does lymph move slowly through the node?
There are several afferent vessels for lymph to enter from but few efferent for lymph to exit, so it must move slowly and wait for a vessel to exit
How is lymph filtered?
Foreign substances are trapped in the sinuses and destroyed by macrophages or lymphocytes. Immune responses and the activation of T cells and memory B cells occur to promote better future defense.
Where is the spleen located?
The ULQ
What does the spleen do?
Filters blood, similar to how lymph nodes filter lymph
What is white pulp?
Lymphatic tissue (Lymphocytes and macrophages)
What is red pulp?
Blood filled venous sinuses and splenic cords
Where does blood enter the spleen?
Via the splenic artery into the white pulp
What occurs in the white pulp?
B and T cells carry out immune functions and macrophages destroy blood borne pathogens
What are the functions of red pulp?
Removal of worn out blood cells/platelets, storage of platelets, production of blood cells during fetal life
What are lymphatic nodules?
Masses of lymphatic tissue that is not surrounded by a capsule. Found throughout the GI, urinary, reproductive and respiratory tracts
Where are Peyer’s patches found?
The small intestine
What is immunity?
The body’s ability to ward off damage or disease through our defense mechanisms
What is innate immunity?
Nonspecific defenses present at birth that act against all microbes
What is the first line of defense in innate immunity?
Skin and mucous membranes
What is the second line of defense in innate immunity?
Antimicrobial substances, phagocytes, natural killer cells, inflammation and fever
What is adaptive immunity?
Specific recognition of specific microbes once it has breached innate immune defenses
What cells are involved in adaptive immunity?
T cells and B cells
What kind of barrier against pathogens does skin create?
A physical and chemical barrier
What happens when skin is damaged?
It opens a potential pathway for pathogens to enter the blood stream
What does the viscous nature of mucous do?
Trap microbes and other foreign substances
What does coughing or sneezing do?
Propels mucous out of the body
What does swallowing mucous do?
Moves the mucous to the stomach to kill the pathogens within with stomach acid
What do tears do?
Wash away pathogens and contains enzymes to destroy them
What does urine do?
Cleanses the urinary tract
When is the second line of defense used?
When pathogens make it past the 1st line of defense
What are the 4 main types of antimicrobial substances?
Interferons, complement system, iron binding proteins, and antimicrobial proteins
What produces interferons?
Lymphocytes, macrophages, and fibroblasts infected with viruses
What do interferons do?
Diffuse into unaffected cells where they aid in production of antiviral proteins that interfere viral replication
What is the complement system?
Normally inactive proteins found in blood plasma that enhance certain immune responses
What is an iron binding protein?
A protein that reduces the amount of available iron required by bacteria for growth
What does a natural killer cell do?
Kills/attacks any body cell that displays abnormal plasma membrane protiens
How does a natural killer cell work?
Binds to a target cell and releases toxic substances that result in the cell inducing apoptosis or creating a hole to cause cytolysis
What are phagocytes?
Neutrophils and macrophages
What do phagocytes do?
Migrate to infected area where monocytes turn into macrophages (wandering macrophages) and fixed macrophages stand guard in specific tissues
What are the steps of phagocytosis?
1.Chemotaxis
2.Adherence
3.Ingestion
4.Digestion
5.Killing
What happens in chemotaxis?
Chemical stimulation for phagocyte to move to a site of damage/foreign substance
What happens in adherence?
Attachment of the phagocyte to a foreign substance
What happens in ingestion?
The plasma membrane engulfs the foreign substance
What happens in digestion?
Phagosome merges with lysosomes in the cytoplasm to form a phagolysosome and enzymes are released
What happens in killing?
Enzymes breakdown what it can of the foreign substance
What happens in killing?
Enzymes breakdown what it can of the foreign substance
What is the remains of the foreign substance after phagocytosis called?
Residual bodies
What is inflammation
A nonspecific defensive response of the body to tissue damage
What is the function of inflammation?
Attempts to dispose of microbes, toxins, or foreign material at the site of injury and prepares the site for tissue repair
What conditions may produce inflammation?
Pathogens, abrasions, chemical irritations, distortion/disturbance of cells, extreme temperatures
What are the signs and symptoms of inflammation?
(PRISH)
Pain
Redness
Immobility
Swelling
Heat
What are the three basic stages of inflammation?
- Vasodilation and increased blood vessel permeability
- Emigration of phagocytes from the blood to interstitial fluid
- Tissue repair
What is acute inflammation?
Rapid onset of symptoms, resolve in days to weeks
What is chronic inflammation?
Slower onset, resolves in months to years
What is a fever?
An abnormally high body temperature (>38C) that commonly occurs in infection/inflammation
What does a fever do?
Intensifies interferon, inhibits some microbe growth, speeds up body reactions that aid in repair
What is an antigen?
A substance that is recognized as foreign and provokes an immune response
What two properties distinguish adaptive immunity from innate?
Specificity and memory
What is clonal selection?
The process of a lymphocyte dividing and differentiating in response to an antigen. Forms an army of clones to attack the specific antigen/
What are the two types of clones?
Effector and memory cells
What is cell mediated immunity?
Cytotoxic T cells directly attack invading antigens. Intracellular pathogens
What is antibody mediated immunity?
B cells transform into plasma cells that synthesize and secrete antibodies or immunoglobulins. Extracellular pathogens
What are major histocompatibility complex antigens?
Unique transmembrane proteins that are identifying markers so T cells can recognize self vs. foreign
What are cytokines?
Small protein hormones that stimulate or inhibit many normal cell functions
What do antibodies/immunoglobulins do?
Match to a specific antigen and neutralize/disable it
What do cytotoxic T cells do?
Kill similar to NK cells but only specific antigens
