Lymphatic System
Two semi-independent parts
lymphatic vessels (similar to blood vessels)
lymphatic organs and tissue
Function: return leaked fluid and patrol for pathogens — only lymph nodes filter lymph
fluid comes from blood
Lymphatic Vessels
low pressure — sucks liquid back to heart like a straw
Lymph capilarries → lymph vessels → lymph trunks
Lymph nodes scattered
Simple squamous epithelium
Lymphocytes
T Lymphocytes - destroy cancer cells
Nodes are located at intersections of lymph nodes
removing lymph nodes change flow of lymph
lymphedema - caused by lymph blockage
can use compression sleeves to reduce the inflammation caused by blockage
Get fluid back to the blood - right at blood vessels that go directly to the heart
means that fluid has to be clean - wbc don’t have time to catch infectors
Lymph Capillaries → Lymphatic Vessels → Lymphatic Trunks
Lymphoid Cells
T-Cells (mature in the thymus)
phagocytes
kill all cells (even your own cells)
identifies Antigen Presenting Cells for B-Cells
B-Cells (mature in the bone marrow)
make antibodies
marking for T-Cells so they can recognize what is bad to kill it
T-Cells & B-Cells are lymphocytes
Lymph Nodes
principle lymphoid organ
concentrated in the inguinal, cervical, and axillary regions
function to filter the lymph and activate the immune system
have more entrances than exits
nodes are bean shaped and laced with trabeculae(network) many afferent vessels enter, few efferent vessels leave
shape determines what it can do
Lymphoid Organs
Spleen
largest lymphoid organ - curls around stomach (left)
site of WBC proliferation
immune surveillance of the blood
stores breakdown products of RBCs
fetal site of erythropoesis
stores thrombocytes
white pulp houses WBCs / red pulp houses RBCs
Tonsils
simplest lymphoid organ, form a ring of lymphatic tissue around the pharynx
palatine tonsils - either side of the posterior end of the oral cavity
lingual tonsils - base of the tongue
pharyngeal tonsil(adenoid)) - posterior wall of nasopharynx
if swollen changes tone in voice
tubal tonsils - surround opening of the auditory tubes into the pharynx
Thymus
secretes thymosin
causes T lymphocytes to become immunocompetent (T cells learn how to do their job in thymus)
overlies the heart in infancy
increases in size and is most active in childhood
stops growing in adolescence and ultimately atrophies
T-cells clone from adolescence because they were already trained when thymus made them competent
Vermiform Appendix
malt - backup in case appendix has to be removed
a blind ended tube at the beginning of the large intestine (colon)
large intestine has a lot of bacteria
e.coli, gut flora (microbiome)
“safe house” for good gut bacteria
if blocked → appendicitis
after an appendectomy, patients often have issues with infections
clostridium difficle colitis - resistant to antibiotics, don’t want to much of it
if appendix is removed other structures can filter blood
Immunology
Innate (nonspecific) Defense - born with it
first line of defense - prevent entry
physical - skin and mucosal membranes, cilia, tears, urine, vomiting
chemical - sebum, lysozymes, gastric fluids, vaginal secretions
second line of defense - inhibit the spread of the pathogen
antimicrobial substances, iron binding proteins, NK cells,
phagocytes, fever, inflammation
Adaptive (specific) Defense - systemic
third line of defense
attacks a specific pathogen
immobilize, neutralize, or destroy foreign substances
amplifies inflammatory response
whole body is inflamed
takes longer to react
has memory (immunity)
recognizes specific proteins of a virus - like a vaccine
Surface Barriers
skin
stratified squamous epithelium
sebum pH ~ 3-5
saliva kill bacteria in the mouth
gastric pH ~ 2
tears dilute microbes
keratin
resistant to weak acids and bases, bacterial enzymes and toxins
mucosal membranes
traps microorganisms
cilia
urine
flushes out bacteria
phagocytes/NK cells
engulf invaders promotes cytolysis
antimicrobial proteins
destroy foreign cell membranes
Mechanism of Inflammation
why inflammation?
prevent the spread of damaging agents to nearby tissue
dispose of cell debris and pathogens
set the stage for repair process
cardinal signs of acute inflammation
P : pain
R : redness
I : immobility
S : swelling
H: heat
Passive Immunity
getting immunity from another source
babies get it from the mother through the umbilical cord and breast milk
Diptheria
heart - myocarditis
nerves - peripheral neuropathy
kidneys - proteinurea
Ro
growth of how infections can travel between people
5.75
Adaptive Immunity
antigen specific
find specific antigens that bind to the proteins and clone them
get rid of the ones that don’t bind
Humoral Immunity (B cells)
antibody-mediated immunity
Cellular Immunity (T cells)
cell-mediated immunity
Humoral Immunity
Active
naturally acquired
infection
contact with pathogen
artificially acquired
vaccine
dead or attenuated pathogen
building your own “army”
Passive
naturally acquired
antibodies pass from mother to fetus via placenta; or to infant in her milk
artificially acquired
injection of immune serum (gamma globulin)
getting someone else’s “army”
Antibodies - Immunoglobulins - in plasma
IgM (pentamer)
first Ig released during the primary response
secreted by both naive and effector B cells
functions as a potent agglutinating agent and activator of B cells
IgD (monomer)
attached to naive B cell surface
function to bind foreign antigens in extracellular fluid and activate B cells
IgA (dimer)
found in lymphoid tissue, sweat, saliva, milk, and intestinal fluids
prevents the attachment of pathogens to epithelial surfaces either inhaled or ingested
mucosal immunity
IgE (monomer)
secreted by effector B cells after isotype switching
causes histamines to be released from basophils
amplifies the inflammation process
IgG (monomer)
secreted by effector B cells after isotype switching
most abundant (75-85%)
protects against bacteria, viruses and toxins in the blood and lymph
main antibody of secondary and late primary response
crosses the placenta