Lymphatic system

1. Lymphatic Organs
ISRAR HUSSAIN YOUSAFZAI
BS (ANESTHESIA) PGRT MSPH
SR. RT, HMC PESHAWAR

2. Lymphatic Organs
1. Spleen
2. Thymus
3. Tonsils

3. Spleen
•The largest lymphoid organ in the body and is highly vascular
•Situated in left hypochondrial region
• Upper left part of the abdomen, behind the stomach and just below the
diaphragm
•Spleen is covered by an outer serous coat and an inner fibro
muscular capsule
•The parenchyma of spleen is divided into red and white pulp

4. Spleen
RED PULP
•Consists of venous sinus and cords of blood cells,
macrophages and mesenchymal cells
WHITE PULP
•It has a central artery, which is surrounded by
splenic corpuscles or Malpighian corpuscles
•These corpuscles are formed by lymphatic sheath
containing lymphocytes and macrophages

5. Functions Of Spleen
1. Formation Of Blood Cells
• In embryo, during the hepatic stage, spleen produces blood cells along with
liver
2. Destruction Of Blood Cells
• Older blood cells are destroyed in the spleen
• When the cells become old, the cell membrane becomes more fragile.
Diameter of most of the capillaries is less or equal to that of cells
• The fragile old cells are destroyed while trying to squeeze through the
capillaries because, these cells cannot withstand the stress of squeezing
• So, the spleen is known as ‘graveyard of blood cells’

6. Functions Of Spleen
3. Blood Reservoir Function
• Large number of RBCs are stored in spleen
• The RBCs are released into circulation during the emergency conditions like
hypoxia and hemorrhage
4. Role In Defense Of Body
• Spleen filters the blood by removing the microorganisms
• The macrophages in splenic pulp destroy the microorganisms and other
foreign bodies by phagocytosis
• Spleen contains about 25% of T lymphocytes and 15% of B lymphocytes and
forms the site of antibody production

7. Thymus
•Situated in front of trachea, below the thyroid gland
•Thymus is small in newborn infants and gradually enlarges till
puberty and then decreases in size
FUNCTIONS
•It plays an important role in development of immunity in the body
•Thymus has two functions:
1. Processing the T lymphocytes
2. Endocrine function

8. Thymus
Processing the T Lymphocytes
•The lymphocytes which are produced in bone marrow are processed
in thymus into T lymphocytes
•It occurs during the period between 3 months before birth and 3
months after birth
•So, the removal of thymus 3 months after birth, will not affect the
cell-mediated immunity

9. Thymus
Endocrine Function of Thymus
•Thymus secretes two hormones:
1. Thymosin
• Thymosin accelerates lymphopoiesis and proliferation of T lymphocytes
2. Thymin
• Thymin is also called thymopoietin
• It suppresses the neuromuscular activity by inhibiting ach release
• Hyperactivity of thymus causes myasthenia gravis

10. Tonsils
•Set of lymphoid organs facing into the aerodigestive tract which is
known as Waldeyer’s ring and consists of:
1. The adenoid tonsils - Roof of nasopharynx
2. Two tubal tonsils - Roof of oropharynx
3. Two palatine tonsils – sides of oropharynx
4. Lingual tonsils – behind tongue

12. Tonsils
Function
•The tonsils serve as the immune system's first line of defense against ingested
or inhaled pathogens
•Engorge with blood to assist in immune responses to common illnesses such as
the common cold
•The tonsils have on their surface specialized antigen capture cells called Micro
fold cell (M cells)
•These M cells then alert the B and T cells in the tonsil that a pathogen is present
and an immune response is stimulated