Chapter #22: The Lymphatic System Flashcards
(45 cards)
Lymphatic system (lymphoid system)
-Protects us against disease
-Lymphatic system cells respond to
–Environmental pathogens
–Toxins
–Abnormal body cells, such as cancers
-contain lymphocytes
Lymphocytes
-Part of the immune response
-Identify, attack, and develop immunity to specific pathogens
-Make up 20–40 percent of circulating leukocytes
-Most are stored, not circulating
-Divide in cortex
-Migrate into medulla
-Mature T cells leave thymus by medullary blood vessels
Components of lymphatic system
- Lymph
- Lymphatic vessels
- Lymphoid tissues and lymphoid organs
- Lymphoid cells
Lymph
A fluid similar to plasma but without plasma proteins
Lymphatic vessels
-Carry lymph from peripheral tissues to veins
-Superficial lymphatics
-Deep lymphatics
–Larger vessels that accompany arteries and veins
-Join to form large lymphatic trunks that empty into two major collecting vessels
–Thoracic duct
–Right lymphatic duct
Lymphoid tissues and lymphoid organs
Scattered throughout body
Lymphoid cells
-Lymphocytes, phagocytes, and other cells
-Immune system cells and supportive cells in lymphoid tissues
Lymphocytes are produced in
-Primary lymphoid tissues and organs
-Red bone marrow and thymus
Lymphocytes are activated in
-Secondary lymphoid tissues and organs
-Tonsils, MALT, lymph nodes, and spleen
Functions of lymphatic system
-Produce, maintain, and distribute lymphocytes and other lymphoid cells
-Return excess fluid to bloodstream
–Maintain normal blood volume
-Transport hormones, nutrients, and wastes
Lymphatic capillaries
-Overlap of endothelial cells acts as one-way valve
–Allows fluids, solutes, viruses, and bacteria to enter
–Prevents their return to intercellular spaces
Lymph flows
lymphatic capillaries to larger lymphatic vessels with one-way valves
Lacteals
-Special lymphatic capillaries in small intestine
-Transport lipids from digestive tract
Thoracic duct
-Base expands to form cisterna chyli, which receives lymph from
–Right and left lumbar trunks
–Intestinal trunk
-Inferior segment collects lymph from
–Left bronchomediastinal trunk
–Left subclavian trunk
–Left jugular trunk
-Empties into left subclavian vein
Right lymphatic duct
-Collects lymph from
–Right jugular trunk
–Right subclavian trunk
–Right bronchomediastinal trunk
-Empties into right subclavian vein
Lymphedema
-Blockage of lymph drainage from a limb
-Causes severe swelling
-Interferes with immune system function
Types of Lymphocytes
- T cells (Thymus-dependent)
- B cells (Bone marrow-derived)
- NK cells (natural killer cells)
Lymphoid tissues
Connective tissues dominated by lymphocytes
Lymphoid nodules (lymphatic nodules)
-Tissue with densely packed lymphocytes
-Germinal center contains dividing lymphocytes
Where are lymphoid nodules distributed?
-Lymph nodes
-Spleen
-Respiratory tract (tonsils)
-Along digestive, urinary, and reproductive tracts
Five tonsils in wall of pharynx
-Pharyngeal tonsil (adenoid)
-left and right palatine tonsils
-two lingual tonsils
Tonsilitis
Inflammation of tonsils, especially palatine tonsils
Mucosa-associated lymphoid tissue (MALT)
-Lymphoid tissues associated with digestive system
-Aggregated lymphoid nodules (Peyer’s Patches)
–Clustered deep to intestinal epithelial lining
Appendix (vermiform appendix)
-Contains a mass of fused lymphoid nodules
-where the small intestine meets the large intestine
