ANAT337-R Lymphatic System

lymph

contains a liquid matrix and white blood cells

drains into blood vessels, delivering molecules to the blood that could not directly enter the bloodstream

to drain body fluids and return them to the bloodstream

Function of lymphatic system

lymphatic capillaries

vessels where interstitial fluid enters the lymphatic system to become lymph fluid

located in almost every tissue in the body, and interlaced among arterioles and venules

lymphatic vessels

similar to veins in terms of their three-tunic structure and the presence of valves

lymphatic trunk

superficial and deep lymphatics eventually merge to form these larger lymphatic vessels

right lymphatic duct

on the right side of the body, the right sides of the head, thorax, and right upper limb drain lymph fluid into the right subclavian vein via this duct

thoracic duct

on the left side of the body, the remaining portions of the body drain into this larger duct

begins just beneath the diaphragm

lymphocyte

primary cells of adaptive immune responses

B cells

immune cells that function primarily by producing antibodies

mature in the bone marrow

plasma cell

activated B cell

differentiated in response to antigen binding and has thereby gained the ability to secrete soluble antibodies

contain large amounts of cytoplasm and rough endoplasmic reticulum

T cell

performs a variety of functions in the adaptive immune response (does NOT secrete antibodies)

matures in thymus

recognizes antibodies on infected cells, secretes chemical messengers, and destroys cells infected with intracellular pathogens

Natural killer cell

among first line of defense

destroy virally infected cells/certain cancerous cells

red bone marrow

bone marrow; a loose collection of cells where hematopoiesis occurs

yellow bone marrow

bone marrow; a site of energy storage, which consists largely of fat cells

thymus gland

a bilobed organ found in the space between the sternum and the aorta of the heart

lymph nodes

function to remove debris and pathogens from the lymph and are sometimes referred to as the “filters of the lymph”

also the site of adaptive immune responses mediated by T cells, B cells, and accessory cells of the adaptive immune system

spleen

a fragile organ without a strong capsule and is dark red due to its extensive vascularization

sometimes called “filter of the blood”

contains red pulp and white pulp

tonsil

lymphoid nodules located along the pharynx’s inner surface and are important in developing immunity to oral pathogens

“encourage” pathogens to penetrate deep into the tonsillar tissues, where they are acted upon by numerous lymphoid follicles and eliminated

MALT

an aggregate of lymphoid follicles directly associated with the mucous membrane epithelia

Peyer’s patches

a type of MALT in the small intestine; especially important for immune responses against ingested substances

contain specialized endothelial cells called M (or microfold) cells that sample material from the intestinal lumen and transport it to nearby follicles so that adaptive immune responses to potential pathogens can be mounted

appendix

engages MALT in its mucosa and submucosa

a blockage of the lumen triggers these cells to elicit an inflammatory response that can lead to complications