LYMPHATIC SYSTEM

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Lymph

• Tissue fluid (interstitial fluid) that enters the lymphatic vessels

• Essentially a drainage system accessory to venous system

• Larger particles that escape into tissue fluid can only be removed via lymphatic system

Functions of lymphatic system

• Network that filters antigens from the interstitial fluid

• Primary site of immune response from tissue antigens

• Lymphatic drainage in all organs of the body except brain, eyes, marrow and cartilage

• Flaccid thin walled channels → progressive caliber

• 600 lymph nodes in body

• Slow flow, low pressure system returns interstitial fluid to the blood system

Tissue fluid

________ (interstitial fluid) that enters the lymphatic vessels.

Components of lymphatics

• Lymph

• Lymphatic Vessels

• Lymphatic Organs

• Lymphatic cells

Lymphatic capillaries

Features of structure:

• Blind end

• Single layer of overlapping endothelial cells

• More permeable than that of blood capillary

• Absent from avascular structures, brain, spinal cord splenic pulp and bone marrow

Lymphatic Vessels

• Three layered wall but thinner than vein

• More numerous valves than in vein

• Interposed by lymph nodes at intervals

• Arranged in superficial and deep sets

Lymph Trunks

• Right and left jugular trunks

• Right and left subclavian trunks

• Right and left broncho mediastinal trunk

• Right and left lumbar trunks

• Intestinal trunk

Lymphatic ducts

• Right lymphatic duct

• Thoracic duct

Lymphatic cells

• Also called lymphoid cells

• Located in both the lymphatic system and the cardiovascular system.

• Work together to elicit an immune response.

Types of lymphatic cells

• Macrophages

• Epithelial cells

• Dendritic cells

• Lymphocytes

Primary organs

• Red bone marrow

• Thymus gland

Secondary organs

• Lymph nodes

• Lymph nodules

• Spleen

Lymph nodes

• Capsular shell

• Fibroblasts and reticulin fibers

• Macrophages

• Dendritic cells

• T cells

• B cells

Head and Neck Nodes

Axillary nodes

Inguinal Lymph Nodes

Lymphargitis

• Inflammation of the lymph vessels

• Commonest cause bacteria called streptococcus pyogenes (most common).

• Lymph vessels appear as red streaks through the skin

Filariasis

Lymphedema

• Occurs due to accumulation of lymphatic fluid in the interstitial tissue

• Sometimes can be appreciated after wearing tight clothing or jewelry on affected limb

Lymphadenopathy

• Means a disease of the lymph nodes

• Lymph nodes become swollen/ enlarged and may be painful to touch

Lymphomas

Cancers originating either from the lymphocytes in the lymph nodes or the lymphatic tissue in organs

Tonsillitis

• Infection of the pharyngeal tonsils

• Tonsils are swollen, Fever and pain during swallowing usually present

Formation and transport of tissue fluid