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Lymphatic System and Body Defense
Chapter 16
Lymphatic System
Lymphatic system consists of lymphatic vessels,
lymphatic organs and associated lymphoid
tissue
Functions contribute to homeostasis
• Helps defend body against disease
• Lymphatic capillaries take up excess tissue fluid
and proteins , and return it to bloodstream
• Lacteals receive lipoproteins and transport
them to bloodstream.
Lymphatic Organs
Thymus
Lymph nodes
Spleen
Major Organs of Lymphatic System
Lymphatic System
Lymphatic
Capillaries
•Microscopic
•Closed-ended tubes with flap like valves
•Found in interstitial spaces of most tissues
•Attached via proteins to surrounding
connective tissue remain open
•Closely associated with the circulatory system
Lymphatic Vessels
•One-way system
that carry lymph
•Valves prevent
backflow
•Lymphatic
capillaries absorb
excess fluid
Lymph Function
Lymphatic capillary
Interstitial spaces
•Lymph - fluid in lymphatic system
•Increasing hydrostatic pressure within interstitial
spaces forces tissue fluid into lymphatic capillaries
•This process prevents accumulation of excess
tissue fluid or edema
Lymph Movement
• action
of skeletal
muscles
• respiratory
movements
• smooth muscle in
larger lymphatic vessels
• valves in lymphatic
vessels
Lymph Nodes
•Macrophages and lymphocytes
•Filter potentially harmful particles from lymph
•Areas of lymphocyte production
Obstruction of Lymph Movement
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• Conditions that
interfere with lymph
movement
Lymphatic
vessels
• Fluid to accumulate
in interstitial spaces
Lymph
node
• Results in edema
Muscle
Blood
vessels
© Dr. Kent M. Van De Graaff
Spleen
Largest lymphatic organ
Function
•Protection from pathogens,
•removes aged RBC recycles Fe
•Blood , platelets, monocyte reservoir
•Fetal blood cell production but not after birth
Spleen
Contains two tissue types
•White pulp
• lymphocytes
•Immune functions
• Red pulp
• Red blood cells
• Lymphocytes
• Macrophages
• Worn out RBC and pathogens are destroyed
Thymus
• Secretes
thymosins
• Site of T
lymphocyte
maturation
• Shrinks with age
Mucosa-Associated Lymphoid
Tissues (MALT)
•
•
•
•
Peyer’s Patches
Lymphoid follicles in appendix
Tonsils of the pharynx and oral cavity
Follicles in urogenital and respiratory tract
• They prevent pathogens in these passages
from penetrating mucous membranes
Diseases of the Lymphatic System
Lymphatic filariasis
• Facts from WHO
• Nearly 1.4 billion people in 73 countries worldwide
are threatened by lymphatic filariasis, a parasitic
infection that leads to a disease commonly known as
elephantiasis.
• Over 120 million people are currently infected, with
about 40 million disfigured and incapacitated by the
disease.
• http://www.cdc.gov/parasites/lymphaticfilariasis/
•
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