The lymphatic system transports lymph through lymph vessels and lymph nodes. Lymph nodes contain B and T lymphocytes and have three layers - cortex, paracortex, and medulla. Lymph enters through afferent vessels and exits through efferent vessels. When infected, lymph nodes swell to fight bacteria and toxins. Lymph is formed from tissue fluid, contains proteins and lipids, and returns about 120 mL to the blood per hour through the thoracic duct.

1. LYMPHATIC SYSTEM
AND LYMPH
Dr. JILSHA

2. OBJECTIVES
To get a better understanding of :
 Lymphatic system
 Lymph nodes and their functions
 Formation, Composition and functions of lymph.

3. LYMPHATIC SYSTEM
 It is a closed system of lymph channels or lymph
vessels through which lymph flows.
 One way system – allows lymph flow from tissue
spaces towards the blood.
 Almost all tissues of the body have lymphatics –
except skin, brain and bones.

4. LYMPHATIC SYSTEM
 Lymphatic system arises from tissue spaces as a
meshwork of delicate vessels – lymph capillaries.
 Large lymph vessels ultimately form the right
lymphatic duct and thoracic duct.
 R lymphatic duct – R subclavian vein.
 Thoracic duct – L subclavian vein.

5. LYMPH NODES
 Small glandular structures located in the course of
lymph vessels.
 Each lymph node constitutes masses of lymphatic
tissue covered by a dense connective tissue capsule.
 Three layers – cortex, paracortex and medulla.

6. STRUCTURE OF A LYMPH NODE

7. STRUCTURE OF A LYMPH NODE
 CORTEX
 Primary and secondary follicles.
 Contains B lymphocytes and macrophages.
 PARACORTEX
 Between cortex and medulla
 Contains T lymphocytes.
 MEDULLA
 Contains B and T lymphocytes and macrophages.

8. LYMPH NODES
 LYMPHATIC VESSELS
 Lymph enters lymph node via Afferent vessels.
 Lymph leaves lymph node via Efferent vessels.
 DISTRIBUTION OF LYMPH NODES
 Along the course of lymphatic vessels in elbow, axilla,
groin, knee.
 Also in neck, thorax and abdomen where many lymph
vessels join.

10. FUNCTIONS OF LYMPH NODES
 Filters lymph – water & electrolytes are
removed, proteins & lipids are retained.
 Bacteria and other toxic substances are
destroyed by macrophages.
 Also called defense barriers.

12. APPLIED PHYSIOLOGY
 During infection, lymph node activity increase –
swelling of lymph nodes.
 Tonsillitis, Throat Ca – neck lymph node (cervical
nodes) swelling.
 Breast Ca – armpit - axillary nodes.
 Lung Ca – chest.
 Genital infections – groin - Inguinal nodes.

14. LYMPH
 Lymph is an alkaline clear fluid that is derived
from interstitial fluid and flowing to blood
stream through lymphatic vessels.

15. FORMATION OF LYMPH
 Lymph is formed from interstitial fluid due to the
permeability of lymph capillaries.
 When blood passes through blood capillaries in the
tissues, 9/10th – into venous end to arterial end,
1/10th - into lymph capillaries.
 Composition of lymph = Insterstitial fluid

17. RATE OF LYMPH
 About 120 ML of lymph flows into blood per
hour.
 About 100 ML – thoracic duct.
 20 ML – right lymphatic duct.

18. COMPOSITION OF LYMPH
 Lymph is a clear and colorless fluid.
 96% water and 4% solids.
 Some blood cells are also present.

20. FUNCTIONS OF LYMPH
 Important function – return proteins from tissue
spaces into blood.
 Redistribution of fluid in the body.
 Bacteria, toxins and other foreign bodies are
removed.
 Maintenance of structural & functional integrity of
tissue.
 Intestinal fat absorption.
 Immunity – transport of lymphocytes.

21. SUMMARY
 Lymphatic system is a closed one way system.
 Lymph node is made of cortex, para cortex and medulla,
afferent & efferent vessels.
 Lymph nodes are present in various regions.
 Infection leads to swelling of lymph node.
 Lymph is a clear fluid.
 Lymph flows into the blood at a rate of 120 mL/hr.
 Foreign bodies are removed in lymph.