Ch. 22 - The Lymphatic System Flashcards
Where are lacteals found and what is their function?
small intestine; carry dietary lipids into lymph vessels and ultimately into blood (lymph is known as chyle)
What is the function of the thoracic duct?
receives lymph from L&R lumbar and intestinal trunks
What is the function of the right lymphatic duct?
where lymph drains into venous blood
Where is the thymus located and what is its function?
mediastinum b/t sternum and aorta; site of T cell maturation
Where is the spleen located and what is its function?
b/t stomach and diaphragm; B/T cells carry out immune functions
What are the 3 tonsils and where are they located?
PALATINE - post. region of oral cavity
LINGUAL - base of tongue
PHARYNGEAL - post. wall of nasopharynx
Where can you find Peyer’s patches?
ileum of small intestine, appendix
What are 3 mechanisms that cause lymph to move back toward the heart?
- respiratory pump
- skeletal muscle pump
- valves in lymphatic vessels
How does the respiratory pump move lymph towards the heart?
pressure changes during inhalation/exhalation; lymph moves from abdominal region to thoracic region
How does the skeletal muscle pump move lymph towards the heart?
fores lymph to move up towards the junction of internal jugular and subclavian veins
How do the valves in lymphatic vessels move lymph towards the heart?
lymph drains into venous blood via R & L lymphatic ducts
How do lymphatic vessels differ from veins?
- lymph capillaries have greater permeability and can absorb larger molec
- one-way structure allows fluid to flow in and not out
- larger diameter, thinner walls, more valves
Where does hemopoiesis take place during fetal development?
blood cells in yolk sac; liver, spleen, lymph nodes
Where does hemopoiesis take place in the adult?
bone marrow (mainly in pelvis, cranium, vertebrae, sternum)
What does immunocompetent mean?
capable of producing an immune response
What is positive selection?
only T-cells that can react are chosen to survive
non-functional T-cells are deleted
What is negative selection?
T-cells that react against antigens in the body are deleted
What are the primary lymphatic organs?
red bone marrow, thymus
What are secondary lymphatic organs?
spleen, lymph nodes, MALT/nodules (mucosal-associated lymphatic tissues)
What is white pulp in the spleen?
first step of filtration of blood
- lymphocytes andmacrophages
What is red pulp in the spleen?
second step of blood filtration
- venous sinuses
- functions in hematopoiesis during fet dev
What comprises of the lymphatic nodules/MALT?
includes tonsils, Peyer’s patches in ileum, parts of appendix
What are some characteristics of innate immunity?
- immediate and non-specific response (no memory)
- physical barriers and internal defences
What are the first line of defense in innate immunity?
skin and mucous membranes; discourage pathogens and foreign substances from entering body
How does the skin act as a line of defense?
- impermeability and tight fit of cells prevent microbe entry
- periodic shedding helps remove microbes
How do mucous membranes act as a line of defense?
- mucous traps microbes
- cilia sweep mucous out (to swallow or sneeze/cough out)
- acids break down microbes
- lysozymes are antibacterial agents
What are the 5 second line (internal) of defenses?
antimicrobial substances NK cells phagocytes inflammation fever
What is the function of antimicrobial substances? Name the 4 main types.
interferons, iron-binding proteins, antimicrobial proteins, complement system
What are interferons?
induce synthesis of antiviral proteins that interfere viral replication
What is the complement system?
proteins cause cytolysis of microbes, promote phagocytosis, contribute to inflammatioin
How do NK cells act as an internal defense?
release chem. that form pores in cell membranes and trigger cytolysis
What are the 5 characteristic signs of inflammation? fev
redness, pain, swelling, heat, loss of function
What are the 3 stages of inflammation?
- vasodilation, increased perm of BV
- emigration of phagocytes via extravasation
- tissue repair
How does fever act as an internal defense?
intensifies effects of interferons, speeds up body rxns that aid repair, inhibits growth of some microbes
What are the 2 key properties of adaptive immunity?
- specificity for antigens (particular foreign molec)
2. memory for previously encountered antigens
What are antigens?
foreign substances that provoke immune responses
What is an epitope?
small part of an antigen molecule that triggers an immune response
What cells or organs are responsible for adaptive immunity?
B & T cells
What are the 2 branches of adaptive immunity?
- cell-mediated immunity
2. antibody-mediated imunity
Where do B and T cells originate and mature?
B - RBM
T - RBM –> thymus
What is clonal selection?
cell with matching receptor was selected to clone itself
What triggers clonal selection?
when an epitope binds to a receptor on the surface of a B or T cell; lymphocyte then proliferates and differentiates in response to that antigen
What are the cells produced by clonal selection?
effector cells or memory cells
What are effector cells and how do they function?
carry out immune responses that result in the destruction/inactivation of the antigen
What are the types of effector cells?
active helper T cells
active cytotoxic T ells
plasma cells (B cells)
What is the function of memory cells?
trigger a quicker rxn if the antigen is encountered again
What are the types of memory cells?
memory helper T cells
memory cytotoxic T cells
memory B cells
Where are adaptive immune responses initiated? (differs as antigens enter different parts of body?
enter bloodstream –> trapped as they flow through spleen
penetrate skin –> lymph vessels then lymph nodes
mucous membranes –> trapped by MALT
What is the difference between helper T cells and cytotoxic T cells?
Helper T - release cytokines to activate other cells of immune system; help activate cytotoxic T & B cells
Cytotoxic T - kill infected body cells
What do activated B lymphocytes differentiate into?
plasma cells and memory B cells
What activates B cells?
free antigens and co-stimulation by helper T cells via release of cytokines
What do plasma cells do?
secrete antibodies into blood and lymph
What is another word for antibody and what does it comprise of?
immunoglobulins; 4 pp chains
What are the 5 classes of immunoglobulins?
IgG, IgA, IgM, IgD, IgE
What is the function of IgG cells and where are they found?
protects against bact/viruses by enhancing phagocytosis, neutralizing toxins, and triggering complement system
blood, lymph, intestines
Which immunoglobulin crosses the placenta from mother to fetus?
IgG
What is the function of IgA cells and where are they found?
provides localized protection of mucous membranes against bact/viruses
found in sweat, tears, saliva, mucus, breast milk, GI secretions
How is IgA related to stress?
when stressed, IgA levels decrease and increase susceptibility to infection
What is the function of IgM cells and where are they found?
activates complement system and causes agglutination and lysis of microbes
found on surface of B cells as antigen receptors
After initial exposure to any antigen, which is the first antibody to be secreted by plasma cells?
IgM
What is the function of IgD cells and where are they found?
activation of B cells
found on surface of B cells as antigen receptors
What is the function of IgE cells and where are they found?
involved in allergic rxns; provides protection against parasitic worms
located on mast cells and basophils
What is the difference between active and passive immunity?
ACTIVE - person’s immune system actively produces antibodies against an antigen; involves lots of memory cells
PASSIVE - person receives pre-made antibodies (in placenta); no memory cells
What are some examples of autoimmune diseases?
type I diabetes, multiple sclerosis, rheumatoid arthritis, myasthenia gravis
Myasthenia gravis…
…antibodies produced against ACh receptors, causing muscle weakness
Type I diabetes mellitus…
…T cells destroy pancreatic island cells that produce insulin
Multiple sclerosis…
…T cells destroy myelin sheaths around axons of neurons
Rheumatoid arthritis…
…inflammatory cells destroy cartilage and synovial membranes
