Chapter 22 Lymphatic System

LS maintaining tissue fluid balance

excess interstitial fluid enters lymphatic capillaries and becomes lymph

LS absorbs fat

transports fats from the small intestine to the veins via lacteals

LS aids in defense

microorganisms and other foreign substances are filtered from lymph by lymph nodes and from blood by the spleen

organs LS

thymus, spleen, bone marrow, tonsils

tissues LS

cervical lymph node, thoracic duct, subclavian veins, lacteals in intestinal wall, inguinal lymph node, lymphatic vessel, mammary plexus, axillary lymph node, right lymphatic duct

lymphatic capillaries function

lymph flows from capillaries into the larger lymphatic vessels, can withstand interstitial pressure and remain open

capillaries structure

single layer overlapping epithelium cells and increased permeability, overlap of epithelial cells allows easy entry of interstitial fluid but prevents movement back into tissue

capillaries location

interstitial spaces, interwoven with blood capillaries

right lymphatic duct

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

thoracic dict

arises from the cisterna chyli and drains lymph from the rest of the body

palatine tonsil location

posterior end of the oral cavity

lingual tonsils location

base of the tounge

pharyngeal tonsils location

adenoids, posterior wall of nasopharynx

tonsil function

first line of defense against ingested or inhaled pathogens

spleen location

left superior side of the abdomen

spleen function

filters the blood

thymus function

secretes the hormones thymosin and thympoietin

thymus location

anterior superior mediatinum, directly behind the sternum, in front of heart

lymph node location

cervical, axillary, and inguinal

lymph node functions

filter lymph and macrophages destroy debris/microorganisms and immune system activation by stimulating lymphocytes

antigens CAI

large molecules that trigger an immune response from the adaptive immune system

foreign antigens CAI

antigens not produced by the body, bacteria, viruses

B-lymphocytes CAI

responsible for antibody-mediated immunity

t-lymphocytes CAI

involved with cell-mediated immunity

innate immunity (nonspecific resistance)

does not show specificity or memory, recognizes all pathogens and launches a general attack

adaptive immunity (specific)

exhibits specificity and memory, recognizes specific foreign substance and produces antibodies

cells in innate immunity

phagocytes (destroy pathogens), natural killer cells (detects and kill virus-infected or tumor cells via apoptosis), mast cells and basophils (release chemical mediators like histamine to promote inflammation)

chemical mediators in innate immunity

cytokines (signaling proteins), antimicrobial peptides and enzymes (defensins and lysozymes presents in secretion that disrupt microbial membranes), and acute phases proteins (opsonize bacteria)

complement cascade in innate

a system of blood proteins activated by pathogen surfaces via three pathways

inflammatory response innate

a localized response to infection or injury, increases blood flow and vascular permeability to allow immune cells to reach site of infection