Lymphatic System


Q. What are the functions of lymphatic system?
A. The functions of lymphatic system are:
 Protects the body from the disease causing agents.
 Transports interstitial fluid formed as a blood filterate back to blood and thus help in maintaining fluid balance.
 Serves as the route by which absorbed fat from the small intestine is transported to the blood.

Q. Enumerate the components of the lymphatic system:
A. Components of the lymphatic system are:
 Circulating lymphocytes
 Lymph vessels
 Central ( primary) lymphoid organs : bone marrow and thymus
 Peripheral (secondary) lymphoid organs : lymph nodes, spleen tonsils, mucosa associated lymphoid tissue.

Q. With the help of flow chart explain the general plan of drainage of lymph.

A.                                                            General Plan of  Drainage of Lymph

lymphatic drainage flow chart

Q. Enumerate the:

a. factors that help in lymph flow
b. tissues/organs where lymph capillaries are absent
c. primary lymphoid organs
d. secondary lymphoid organs
e. areas drained by thoracic duct
f. areas drained by right lymphatic duct
g. types of lymphocytes and their function
f. sites where lymph capillaries are absent


A. a. Factors that help in lymph flow:

 Tissue fluid pressure
 Contraction of surrounding muscles
 Pulsations of adjacent arteries
 Negative intrathoracic pressure
 Presence of valves which prevent back flow

b. Lymphatic capillaries are absent in:

 All avascular structures i.e. epidermis, cornea, nail, hair and cartilage
 Spleen and bone marrow
 Alveoli and respiratory bronchiole
 Brain and spinal cord

c. Primary lymphoid organs are:

 Bone marrow
 Thymus

d. Secondary lymphoid organs are:

 Lymph node
 Spleen
 Tonsil
 Mucosa associated lymphoid tissue
o Gut associated lymphoid tissue (GALT)
o Bronchii associated lymphoid tissue (BALT)


e. Areas/regions drained by thoracic duct:right lymphatic duct and thoracic duct

 Lower limbs
 Abdomen
 Left thoracic region
 Left upper limb
 Left side of head and neck

f. Areas/regions drained by right lymphatic duct:

 Right upper extremity
 Right thoracic region
 Right side of head and neck

g. Types of lymphocytes:

B lymphocytes:
o Are derived from precursor cells in bone marrow and they also mature within the bone marrow.
o Mature cells migrate to secondary lymphoid organs.
o On being exposed to antigens they proliferate and produce antibody producing cells – plasma cells, and memory cells.
o Are responsible for antibody mediated ( humoral ) response.

T lymphocytes:
o Immunologically immature T lymphocytes migrate from bone marrow to thymus.
o Immature T lymphocytes proliferate and acquire variety of surface markers and become immunologically competent cells.
o Types of T lymphcytes:

 T helper cells
 Cytotoxic T cells
 Suppressor T cells

o Are responsible for cell mediated antibody.

f.Sites where lymph capillaries are absent

  • Epidermis
  • Cornea
  • Hair
  • Nail
  • Cartilage
  • Bone marrow
  • Central nervous system ( brain and spinal cord)

Q. Explain the following:

a. Lymphangitis
b. Lymphadenitis
c. Elephantiasis

A. a. Lymphangitis

• Is the inflammation of the lymphatic vessels .
• Is caused by inflammatory conditions of the skin caused by bacterial infections.
• Thin red lines may be observed running along the course of the lymphatic vessels in the affected area,.
• Is accompanied by painful enlargement of the nearby lymph nodes.

  b. Lymphadenitis

• Occurs when the lymph nodes become overwhelmed by bacteria, virus, fungi, cancer cells, or inflammation.
• The swollen lymph nodes are usually found near the site of an underlying infection, tumor, or inflammation.

c. Elephantiasis

 Massive swelling and enlargement of the limbs resembling elephant’s leg.
 Adult worms of filariasis are lodged in the lymph vessels of leg and foot which causes blokage of lymph flow and as a result fluid accumulates in interstitial spaces leading to edema.

abnormalitis of lymphatic drainage


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