Lymphatic System and Immune Response

Flashcards covering key terms and concepts related to the lymphatic system and immune response.

function of lymphatic system

maintenance of fluid balance

returns fluids that leaked from blood vessels

lymphoid organs and tissues

• provides strucural basis of immune system

• house phagocytic cells and lymphocytes

structure of organs and tissues

spleen, thymus, tonsils, lymph nodes, other lymphoid tissues

lymphatic vessels

return interstitial fluid and leaked plasma proteins back to blood

once interstitial fluid enters lymphatics it is called

lymph

lymph flows toward the heart through a

one-way system

lymphatic capillaries

very permeable

absent from bones, teeth, bone marrow and central nervous system

pathogens travel throughout body through lymphatics

lymph

comparable to blood plasma

has wbc

chyle

lymph formed in the digestive system that is rich in triglycerides (fat) ad looks milky white

lymphatic ducts

empties lymph into venous circulation at the junction of internal jugular and subclavian veins

right lymphatic duct

drains right upper arm and right side of the head and thorax

lymph is propelled by

• milking action of skeletal muscle

• pressure changes in thorax during breathing

• pulsation of nearby arteries

• contractions of smooth muscle in walls of lymphatics

• valves to prevent backflow

lymphocytes

main warriors of immune system that arise in red bone marrow

lymphocytes mature into what two main varieties

t cells and b cells

lymphocytes function

protects against antigens like bacteria, toxins, viruses, cancer, mismatched rbcs

macrophages

phagocytize (eat) foreign substances; help activate t cells

dendritic cells

capture antigens and deliver them to lymph nodes; activate t cells

reticular cells

produce reticular fiber stroma that supports other cells in lymphoid organs

lymph nodes

principal lymphoid organs of the body that are embedded in connective tissue

common causes of swollen cervical lymph nodes

bronchitis, common cold, ear infections, scalp infections, strep throat, tonsillitis, ear/nose/throat/mouth infection

area where lymph nodes can be felt

groin, armpit, behind the ears, back of the head, sides of the neck, under the jaw/chin

lymph nodes functions

filter lymph by macrophages destroying microorganisms and debris

it activates the immune system; lymphocytes activated and mount attack against antigens

structure of a lymph node

largest lymphoid organ

spleen

functions of spleen

site of lymphocyte proliferation

cleanses blood of aged cells/platelets

stores breakdown products of rbc

white pulp area of the spleen is

around central arteries

red pulp area of the spleen is

in venous sinuses and splenic cords

Thymus

maturation area for t-cells

increases in size and most active during childhood

thymic lobules

contain outer cortex and inner medulla

largest collections of Mucosa-associated Lymphoid Tissue (MALT)

are found in tonsils, appendix, Peyer’s patches (lymphoid follicles)

Mucosa-associated Lymphoid tissue (MALT)

lymphoid tissue in mucous membrane throughout the body that protects from pathogens trying to enter the body

simplest lymphoid organ

tonsils

tonsils

• contain follicles with gerinal cneters

• not fully encapsulated

tonsils have overlying epithelium that invaginates forming what

tonsillar crypts that tray/destroy bacteria and allows immune cells to build memory for pathogens

appendix

serves as a haven for useful bacteria

blind-ended tube connected to the cecum

Peyer’s patches and appendix

generate “memory” lymphocytes

destroy bacteria

3

there are ___ times as many cells from bacteria, archaea, etc living in you than you can cell (which is about 10 trillion)

immunity

resistance to disease (immune = free)

innate defense system in nonspecific

surface barriers: skin. mucosa

internal defenses: anti-microbial proteins, phagocytes, inflammation

adaptive defense system is specific but slow

humoral immunity: b-cells

cellular immunity: t-cells

innate defense

mechanical surface barriers that ward off invading pathogens

chemical surface barriers

protective chemicals inhibit/destroy microorganisms

defensins

antimicrobial peptides and inhibit their growth

internal defenses (specifically cells and chemicals)

necessary if microorganisms invade deeper tissue

phagocytes, natural killer (NK), antimicrobial proteins, fever, inflammatory response

phagocytes include

neutrophils and macrophages

Neutrophils

most abundant WBC, but die fighting

macrophages

develop from monocytes and are the chief phagocytic cells

phagolysosome

when phagosome fuses with lysosome

mechanisms of phagocytosis

phagocyte must adhere to particle

cytoplasmic extensions bind to/engulf particle in vesicle called phagosome

inflammatory response

• triggered whenever body tissues injured

• prevents spread of damaging agents

• disposes of cell debris and pathogens

• alerts adaptive immune system

• sets the stage for repair

cardinal signs of acute inflammation

redness, heat, swelling, pain, impairment of function

what are the chemical signals released by damaged cells

kinins, prostaglandins (PGs), and complement

aspirin

relives some of the effects of pain, fever, and blood clotting

kinins, prostaglandins (PGs), and complement

dilate arterioles (hyperemia)

make capillaries leaky (so wbc can get out)

many attract leukocytes to area