lecture 10 lymphatic system review

functions of lymphatic system

• Drains excess interstitial fluid back into the bloodstream

• Transports dietary lipids

• Houses and develops lymphocytes (WBCs)

components of the lymph system

• Lymph Vessels

  • Lymphatic capillaries

  • Lymphatic vessels

  • Lymphatic trunks

  • Lymphatic ducts

• Lymph Fluid

• Lymph Cells

• Lymph Structures

  • Lymph nodules, tonsils, MALT

• Lymph Organs

  • Spleen, thymus, lymph nodes

lymph capillaries

• closed-end tubes in blood capillary networks that collect excess interstitial fluid

• Larger in diameter than blood capillaries

• One-way flaps open to allow fluid to enter

lacteals

• specialized lymphatic capillaries in the small intestine

  • Collect lipids to eventually return to blood stream

  • Chyle: fatty lymph

• lymph capillaries

lymphatic (lymph) vessels

• travel alongside blood vessels and carry lymph fluid towards heart

• Resemble veins:

  • Same 3 tunics, but much thinner

  • More valves than veins

• connect to lymph nodes (filled w/WBC) that filter and monitor the fluid

lymph trunks

• tributaries of small lymph vessels that drain large regions of the body

• lymphatic ducts

lymphatic ducts

• 2 large lymph vessels that drain all lymph fluid back into the blood

  • Right Lymphatic Duct

  • Thoracic Duct

    • Cisterna Chyli

right lymphatic duct

drains right face/neck, chest, and arm

thoracic duct

• drains lymph from the rest of the body

  • cisterna chyli: collects chyle before entering the duct

lymphopoiesis

• All lymphocytes originate in the red bone marrow.

• Maturation:

  • B-Cells (antibodies) in the bone marrow

  • T-Cells in the thymus

• Fully mature lymphocytes become immunocompetent

  • Able to recognize invaders (antigens) and perform their various functions

• Travel from blood to lymphoid tissues

lymph nodules

• lymph structures within tissues that attack invaders

  • Similar to lymph nodes but without capsule

  • Doesn’t filter lymph fluid because it’s not located along a lymph vessel.

• Structure:

  • Germinal center has B-cells

  • T-cells outside germinal center

tonsils

• are large lymph nodules with multiple germinal centers

• Form crypts to help trap material

mucosa associated lymphatic tissue (MALT)

• initiates immune responses to specific invaders encountered along all mucosa surfaces

  • GI, respiratory, genital, and urinary tracts

lymph organs

• Completely surrounded by a CT capsule

• Gather and destroy infectious microorganisms

• Store lymphocytes

• Main organs:

  • Thymus

  • Lymph nodes

  • Spleen

thymus

• organ in anterior chest where T-cells mature

  • Large in infants/young children → pathogen exposure creates immunity

  • Atrophied in adults

• Structure:

  • Divided into various regions of cortex and medulla

  • Cortex: contains many T-cells

  • Medulla: releases hormones to encourage T-cell maturation

• lymph organs

lymph nodes

• clusters of lymphatic cells along pathway of lymph vessels that filter lymph fluid and mount immune response

  • Surrounded by capsule (b-cells & t-cells)

• lymph organs

stage 0 cancer

• abnormal growth

  • Benign tumor (in one location)

stage 1 cancer

Small tumor contained to one area. Break through basement membrane

stage 2 cancer

cells enter underlying CT

stage 3 cancer

cells spread to nearby lymph nodes and enter circulation

stage 4 cancer

cells metastasize and spread widely to distant parts of the body or other organs

spleen

• Large lymph node – phagocytize foreign cells and initiate immune response in blood (not lymph)

• Reservoir for erythrocytes and platelets

• Phagocytize old erythrocytes and platelets

• Site of hemopoiesis in the fetus

• lymph organs

white pulp

• immune functions

  • Leukocytes

  • Destroy blood-borne invaders

• spleen structure

red pulp

• blood functions

  • RBC destruction

  • Splenic sinusoids for RBC exit/entry

• spleen structure