Module 15: The Lymphatic and Immune Systems Flashcards
Lymphatic trunks
Collect lymph from large regions of the body into two specific lymphatic ducts
Lymphatic ducts
Right lymphatic duct
Thoracic duct
Right lymphatic duct
Receives lymph from the vessels in the right upper
regions of the body
Drains into the right subclavian vein and then into the superior vena cava
Thoracic duct
Receives lymph from the rest of the body
Drains into the left subclavian vein and then into the superior vena cava
Cisterna chyli forms the beginning of the thoracic duct
Lymph nodes
~600, in clusters along lymphatic vessels
Filter and clean lymph (Phagocytic cells remove and destroy microorganisms, cellular debris, cancerous cells, etc.)
Contain lymphocytes that provide protection from foreign invaders and other substances
Structure of lymph nodes
Usually bean shaped and about 2.5 cm (1 inch) in length Capsule Cortex Medulla Trabeculae Sinuses Germinal centers of the follicles (nodules) Afferent vessels Efferent vessels
Cortex
Outer region
Contains T cells and B cells
Medulla
Inner region
Contains B cells and plasma cells
Trabeculae
Divide nodes into compartments
Germinal centers
Contain dividing lymphocytes
Afferent vessels
Transport lymph into the node
Efferent vessels
Transport lymph out of the node
Spleen
Largest lymphatic organ in the body
Surrounded by a thin capsule
Consists of two areas of tissue called white pulp (contains mostly lymphocytes)
and red pulp (where old red blood cells are destroyed)
Forms blood cells during fetal development
Filters and stores blood
Destroys old red blood cells and foreign material
Stores lymphocytes
Thymus
Within the mediastinum, behind the sternum
Pinkish gray colour during childhood and yellowish in old age as the tissue is replaced with fat
Composed of two lobes
Provides a source of lymphocytes before birth
Secretes hormones that stimulate T cells to attack pathogens
Tonsils
Clusters of lymphatic with structures called crypts that
trap foreign substances
Protect the body against bacteria and other pathogens from entering the area around the openings to the nasal and oral cavities
Palatine tonsils
On each side of the throat near the opening of
the oral cavity into the pharynx