lymphatic and immune system

lymph(part of lymphatic system)

a fluid similar to plasma

does not have plasma proteins

lymphatic vessels(lymphatics)- (part of lymphatic system)

network that carries lymph from peripheral tissues to the venous system

lymphoid tissues and lymphoid organs (part of lymphatic system)

found throughout the body

last part of lymphatic system

lymphocytes, phagocytes, and other immune system cells

lymphatic and immune functions

drain excess interstitial fluid- 3 liters needs to be reabsorbed but not for exchange- just collected, lymph systems use WBCs to clean fluid and return back to blood stream

lymph- when interstitial fluid enters system it becomes this

transport dietary lipids- when fat absorbed in GI tract and fat soluble vitamins are transported in lymph system

carry out immune responses- immune system in lymphatic system

lymphatic capillaries

collection only, no exchange

closed at 1 end, contain valves, 1 way flow into capillary and back to heart have larger diameters and thinner walls than blood capillaries

location: space between cells, run with blood capillaries

endothelial cells

important in maintaining 1 way flow into lymphatic capillaries

anchoring filaments

used to keep lymphatic capillaries open, prevent collapse

lacteals

specialized lymphatic capillaries in small intestine to carry lipids from diet

chyle

specialized white lymph(contains fat) from lacteals

lymphatic flow

blood capillaries(blood)→ interstitial space(interstitial fluid)→ lymphatic capillaries(lymph)→ lymphatic vessels(lymph)→ lymphatic ducts→ subclavian veins(blood)

-use skeletal and respiratory pumps(no pressure in lymphatic system)

-return from pulmonary and systemic circuits to subclavian veins(caps→ vessels→ trunk→ ducts)

the lymphatic system is very left sided,

lower body drains into the thoracic duct(left side)

left subclavian vein

thoracic duct

• left jugular trunk(head, neck)

• left subclavian trunk(arm)

• left bronchomediastinal tract(chest)

cisterna chyli

• intestinal trunk

• (R&L) lumbar trunks(legs)

right subclavian vein

right lymphatic duct

• right jugular trunk

• right subclavian trunk

• right bronchomedistinal trunk

primary organs and tissue

where stem cells divide and develop(factory)

red bone marrow (primary)

produce hemocytoblasts→ produce B cells and pre-T cells

thymus gland (primary)

matures(educates) T cells

secondary organs and tissues

where immune response occurs(battle field)

• lymph nodes

• spleen

• lymphatic nodules

lymph nodes (secondary)

lymph will flow from 1 node to the next

lymph nodes

about 600 located along lymph vessels

concentrated in: breast, axillary, and groin

lymph divides into: capsules

outer covering

lymph divides into: outer cortex

contains mostly B cells and macrophages

lymph divides into: inner cortex

contains mostly T cells

lymph divides into: medulla

B cells, antibodies from plasma cells, and macrophages

lymph node flow

afferent lymphatic vessel(into node)→ subcapsular sinus→

trabecular sinus→

medullary sinus→

efferent lymphatic vessel(out of node)

designed to pass lymph by different WBCs

metasis

secondary tumor sites can be predicted according to the direction of lymph flow from primary tumor site

• not tender like inflamed nodes

• use to dye to detect central node for biopsy

spleen

largest mass of lymphatic tissue

location: left side between stomach and left kidney

capsule(spleen)

outer covering, contains hilus(splenic arteries, veins, and efferent lymph vessels)

parenchyma(spleen)

center of spleen, 2 tissues

white pulp(spleen)

lymphatic tissue, lymphocytes and macrophages are located around a central artery(branches of the splenic artery)

red pulp(spleen)

blood filled venous sinuses, contain RBCs, leukocytes, and plasma cells

functions of spleen

1. remove worn out RBCs

2. store platelets- 1/3 of body total

3. produce blood cells when fetus

blood enter white pulp where it is “phaged”- gets rid of blood born pathogens→ then into red pulp→ then splenic veins

thymus gland

location: sit on top of heart, covered by capsule, larger in kids

cortex(thymus gland)

pre T cells(immature cells) collect here from red bone marrow, this is where they will mature

medulla(thymus gland)

contains more mature T cells

epithelial cells( thymus gland)

helps “Education” of T cells by ‘positive selection’, only 20% make it, T cells leave thymus to collect in spleen, lymph nodes, and lymphatic tissue

lymphatic nodules

spread through different areas of the body

egg-shaped masses of lymphatic tissue not covered by a capsule

tonsils

lymphatic nodules in the oral cavity

pharyngeal(tonsil)

posterior wall of nasopharynx

palatine(tonsil)

back side of oral cavity(removed)

lingual(tonsil)

back base of tongue

MALT(mucosa-associated lymphatic tissue)

spread through out connective tissue of GI tract, urinary, and reproductive systems

lymphoid tissues associated with digestive system(peyer’s patch)

clustered deep to intestinal lining epithelial lining

appendix

mass of fused lymphoid nodules

nonspecific resistance

• present at birth

• offers immediate protection against variety of pathogens

• functions same way regardless of the type of invader

first line of defense

physical and chemical barriers discourage pathogens from penetrating the body and causing disease

skin(epidermis) (1st defense)

provides a tough physical barrier

mucous membranes (1st defense)

traps many microbes and foreign substances

lacrimal apparatus (1st defense)

provides tears to wash away irritants to the eyes

saliva (1st defense)

reduces growth of microbes in the mouth

urine flow (1st defense)

cleanses the urethra

gastric juice (1st defense)

strong acidity destroys many pathogens

internal antimicrobial proteins (2nd defense)

found in blood and interstitial fluid, discourages growth of microbes

interferons (2nd defense)

prevent viruses from replicating

complement system (2nd defense)

found in blood plasma and plasma membranes, when activated enhances immune reactions- stimulation of inflammation, attraction of phagocytes, enhancement of phagocytosis by complements working with antibodies, and destruction of target cell membranes by complement proteins

transferrins (2nd defense)

iron binding proteins, reduces iron needed for bacterial growth

natural killer cells

5-10% of lymphocytes, attack cells that display abnormal plasma membrane proteins

phagocytes

specialized cells that ingest microbes and other cellular debris

example of phagocytes

neutrophils and macrophages

chemotaxis

chemically stimulated movement of phagocytes

adherence

attachment of phagocyte to microbe

ingestion

process of engulfing the microbe

digestion

uses digestive enzymes and strong oxidates

killing

digestion and oxidation kills microbe

inflammation

defensive response to tissue damage

attempt to dispose of microbes, toxins, and foreign material at the site of injury to prevent spread to other tissues, and to prepare site for repair

signs of inflammation

redness, pain, heat, swelling

inflammation examples

pathogens, abrasions, chemical irritation, cell disturbance, or extreme temperature

inflammation process

Injured cells release Prostaglandins, proteins, potassium ions

Changes interstitial environment and stimulates mast cells

Mast cells release histamine (increases capillary permeability) & heparin (inhibits clotting)

Increased blood flow- raises local temperature, causes area to swell, redden, and become painful

Blood clot forms around damaged area, isolating it

Complements break down bacteria & attract phagocytes

Activated neutrophils attack debris and bacteria

Phagocytes and foreign proteins activate body’s specific defense system

Macrophages clean up pathogens and cell debris

Fibroblasts form scar tissue

necrosis(products of inflammation)

local tissue destruction in area of injury

pus(products of inflammation)

mixture of debris and necrotic tissue

abscess(products of inflammation)

pus accumulated in an enclosed space

fever

abnormal high body temperature that occurs because of hypothalamic thermostat reset

• intensifies effects of interferons, inhibits some microbe growth, speeds up reactions that aid in attack and repair

pyrogens

any material that causes the hypothalamus to raise body temperature including circulating pathogens. toxins, or antibody complexes

immunity((adaptive defenses)

ability to mount a specific resistance against specific antigens

specific(adaptive defenses)

ability to signal out foreign substances for destruction, also recognize self

memory(adaptive defenses)

to be able to remember an antigen and kill it faster next time

systemic(adaptive defenses)

affects the whole body-not restricted to the area of infection

antigens(adaptive defenses)

anything is perceived as foreign due to surface proteins

examples of antigens

viruses, bacteria, cancers, bacterial toxins, pollen, incompatible blood cells

3 common pathways to lymphatic tissue

• enter blood stream and are trapped as they flow through the spleen

• penetrate the skin, enter lymphatic vessels and get lodged in lymph nodes

• penetrate mucous membranes and become entrapped by MALT

antigen receptors

before T cells leave the thymus and B cells leave red bone marrow they insert specific proteins into the plasma membrane capable of recognizing specific antigens

T cells

kill other cells

B cells

produce plasma cells that produce antibodies

major histocompatibility complex(MHC)(self-antigens)

these are the body’s self antigens, a protein on the surface of all cells, how the body recognizes its own cells(except RBCs)

Class 1 MHC(self-antigens)

appear on all body cells except RBCs

Class 11 MHC(self-antigens)

appear only on activated T cells and cells of the thymus

cell-mediated immunity cells(cells attacking cells)

1) Antigen is Presented (APC’s)- antigen gets noticed/discovered, bumps into WBC, antigen presenting cell 🡪 migrates to lymphatic tissue to present antigen to T cell

2) Activation of T cell- antigen causes a small

number of T cells to activate

3) Costimulation (interleukin-2)- activation is

complete after a second chemical confirmation

(costimulation)- prevents unneeded immune

responses

4) Proliferate- makes copies of itself (divides) from a few to thousands

5) Differentiate- forms different more specialized copies

Helper

Cytotoxic

Memory- storage for future invasion

6) Elimination (all T cells kill this way)

Perforin

Lymphotoxin

Helper

(CD4) recognizes MHC-II’s – secretes interluken 2 (provides more costimulant)

cytotoxic

(CD8) recognizes antigens combined with MHCs 1’s(body cells with: virus, tumor cell), cells gone bad

perforin

punches holes in the plasma membrane of target cell

lymphotoxin

activates enzymes in target cell that destroy cells DNA

antibody-mediated immunity

1) Binding & Activation of B cell- B cells can bind directly to antigen but are much more efficient when antigen is presented to B cells

2) Costimulation by T helper cell

3) Proliferate- B cells divide

4) Differentiate- turn into memory & plasma cells

Memory cells

Plasma cells (live 4-5 days) produce hundreds to millions of antibodies

Antibodies- antibodies bind with antigen (with

different results)

5) Antibody Action

antibody structure

2 parallel pairs of polypeptide chains: 1 pair of heavy chains and 1 pair of light chains

each chain contains constant segments and variable segments

classes

distinctive chemical structure

IgG(antibodies)

most abundant(80%), protects against bacteria, viruses, toxins and triggers complement system, can cross placenta from M→ F(immunity to newborns)

IgA(antibodies)

10-15%, found in secretions- tears, mucus, saliva, breast milk, GI- protects mucus membranes from bacteria and viruses

IgM(antibodies)

5-10%, first secretion of plasma cells, activates complement system, are antigen receptors on B cells, anti-A and anti-B antibodies in blood plasma

IgD(antibodies)

rare, act as B cell antigen receptors, activation of B cells

IgE(antibodies)

rare, act as receptors on mast cells and basophils, involved with allergic and hypersensitivity reactions, help against parasitic worms

neutralizing

stops reactivity